Search found 108 matches
- Mon Mar 15, 2021 10:25 am
- Forum: Administrative Questions and Class Announcements
- Topic: THANK YOU DR LAVELLE!
- Replies: 47
- Views: 7056
Re: THANK YOU DR LAVELLE!
Thank you so much much Dr Lavelle for a great two quarters in 14A/B! It was a great year learning "good chemistry" and I could not have asked for a better professor my first year at UCLA! Thank you for working so hard to ensure that we all understood the content and by making us feel like ...
- Sat Mar 13, 2021 9:25 pm
- Forum: Experimental Details
- Topic: Determining Real Rate Constant from Pseudo Rate Constant
- Replies: 1
- Views: 1849
Re: Determining Real Rate Constant from Pseudo Rate Constant
Hi, You are exactly on the right track! In order to find the rate constant from the pseudo rate constants we first have to determine all the orders for the respective reactants and then use the pseudo rate constant for one of the reactants and divide it by the reactants to power of their orders. We ...
- Sat Mar 13, 2021 9:20 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Control of Reactions
- Replies: 3
- Views: 350
Re: Control of Reactions
Hi, You can tell if a reaction is controlled by kinetics or thermodynamics by seeing if it occurs spontaneously and if it does what is the rate at which it occurs. For instance, in his lectures Dr Lavelle used the conversion of diamond to graphite as an example. Even though this reaction occurs spon...
- Fri Mar 12, 2021 11:53 pm
- Forum: Balancing Redox Reactions
- Topic: Textbook Excercise 6L.3 Part D
- Replies: 2
- Views: 302
Textbook Excercise 6L.3 Part D
Hi
I hope all is well.
When doing 6L.3 part d, I was confused on how to balance the equations since we are not given whether the reactions occur at basic/acidic conditions. Are we supposed to assume one condition over the other?
Thank you so much for all your help and good luck studying :)
I hope all is well.
When doing 6L.3 part d, I was confused on how to balance the equations since we are not given whether the reactions occur at basic/acidic conditions. Are we supposed to assume one condition over the other?
Thank you so much for all your help and good luck studying :)
- Thu Mar 11, 2021 12:18 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Conductors
- Replies: 2
- Views: 213
Re: Conductors
Hi,
In general, I think it is important to know that metal solids are conducting where as non metal solids do not tend to conduct electricity.
I hope this helps :)
In general, I think it is important to know that metal solids are conducting where as non metal solids do not tend to conduct electricity.
I hope this helps :)
- Thu Mar 11, 2021 12:13 pm
- Forum: Balancing Redox Reactions
- Topic: Summary of Balancing Redox Reactions
- Replies: 2
- Views: 323
Re: Summary of Balancing Redox Reactions
Hi, In general when balancing redox reactions you must first divide the reaction into the reduction and oxidation half reactions. Afterwards, you must balance each half reaction based on the acidic/basic conditions mentioned. In each half reaction make sure to include the number of electrons gained ...
- Tue Mar 09, 2021 12:54 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: H+ in cell diagram
- Replies: 2
- Views: 204
Re: H+ in cell diagram
Hi, For cell diagrams, you would include what is the final combined equation of what is occurring in the galvanic cell. Therefore, I am pretty sure this would depend on a case by case scenario depending on what the final balanced equation is(but in most cases I've seen on homework it was not necessa...
- Sun Mar 07, 2021 9:49 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Change in Cell Potential
- Replies: 5
- Views: 336
Re: Change in Cell Potential
Hi,
The cell potential is the difference in charge between the reducing and oxidizing agents. Therefore, I am pretty confident that if water is added it should not affect the cell potential unless it is directly involved as a reducing or oxidizing agent, which isn't very likely.
Hope this helps :)
The cell potential is the difference in charge between the reducing and oxidizing agents. Therefore, I am pretty confident that if water is added it should not affect the cell potential unless it is directly involved as a reducing or oxidizing agent, which isn't very likely.
Hope this helps :)
- Sun Mar 07, 2021 9:47 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Balancing half-reactions to find overall cell potential
- Replies: 6
- Views: 399
Re: Balancing half-reactions to find overall cell potential
Hi,
You do not multiply the cell potential, since E tells you the voltage/charge different between the reducing and oxidizing agent and that difference remains constant no matter how many molecules/electrons are involved in the reaction.
I hope this helps :)
You do not multiply the cell potential, since E tells you the voltage/charge different between the reducing and oxidizing agent and that difference remains constant no matter how many molecules/electrons are involved in the reaction.
I hope this helps :)
- Sun Mar 07, 2021 9:46 am
- Forum: Zero Order Reactions
- Topic: Half-life equations
- Replies: 3
- Views: 202
Re: Half-life equations
Hi,
The half life equations for each order are different because you derive the equations from each order's individual integral rate law, which is different depending on the rate of the reaction.
I hope this helps :)
The half life equations for each order are different because you derive the equations from each order's individual integral rate law, which is different depending on the rate of the reaction.
I hope this helps :)
- Sun Mar 07, 2021 9:45 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: flipping sign of E˚
- Replies: 7
- Views: 429
Re: flipping sign of E˚
Hi!
If you flip the equation then you should also flip the sign of E since now the substances are flipped where the reducing agent is now the oxidizing agent and vice versa.
I hope this helps :)
If you flip the equation then you should also flip the sign of E since now the substances are flipped where the reducing agent is now the oxidizing agent and vice versa.
I hope this helps :)
- Sun Mar 07, 2021 9:43 am
- Forum: Zero Order Reactions
- Topic: Overall order of the reaction
- Replies: 45
- Views: 2239
Re: Overall order of the reaction
Hi,
The overall order of the reaction can be found by adding the individual orders of each reactant.
I hope this helps :)
The overall order of the reaction can be found by adding the individual orders of each reactant.
I hope this helps :)
- Sun Feb 28, 2021 11:38 am
- Forum: Balancing Redox Reactions
- Topic: Balancing with H2O/OH-
- Replies: 6
- Views: 368
Re: Balancing with H2O/OH-
Hi, When balancing equations you have to know if it is under acidic or basic solution conditions. When balancing the redox reactions first split the equations into their half reactions and determine how many electrons are being lost or gained and add that to your half reactions. If the reaction occu...
- Sun Feb 28, 2021 11:33 am
- Forum: Balancing Redox Reactions
- Topic: Sapling Week 7/8 Question 5
- Replies: 1
- Views: 162
Sapling Week 7/8 Question 5
Hi,
Can someone help me balance this equation? Each time I do it my charges do not balance out. I've attached the problem below.
Thank you so much for all your help :)
Can someone help me balance this equation? Each time I do it my charges do not balance out. I've attached the problem below.
Thank you so much for all your help :)
- Sat Feb 27, 2021 11:14 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: -d[R]/dT versus d[P]/dt
- Replies: 13
- Views: 945
Re: -d[R]/dT versus d[P]/dt
Hi, These two equations will equal one another if they both have the same stoichiometric coefficients in the balanced chemical equations or if you divide each product or reactant by their respective stoichiometric coefficient. This equation tells us that the concentration of reactants is decreasing ...
- Sat Feb 27, 2021 11:11 am
- Forum: Administrative Questions and Class Announcements
- Topic: Step up vs workshops
- Replies: 18
- Views: 1162
Re: Step up vs workshops
Hi, Step up sessions are used to provide individuals with a step by step process on how to approach and problem solve the questions we learned that specific week. They are helpful if you need more clarification on how to approach problems in the given section we are learning. Workshops are similar t...
- Sat Feb 27, 2021 11:08 am
- Forum: General Rate Laws
- Topic: Rxn Rate Law for Lecture 21
- Replies: 3
- Views: 260
Re: Rxn Rate Law for Lecture 21
Hi! Although both dividing and multiplying end up with the same answer, when dividing each individual reaction rate by the stoichiometric coefficient we can find a law and method that applies to all chemical reaction rates despite their stoichiometric coefficients. Consequently, this provides us wit...
- Sun Feb 21, 2021 11:03 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Voltage
- Replies: 5
- Views: 332
Re: Voltage
Hi,
Voltage is the electrical potential energy difference between the cathode and the anode. Consequently, it is also a measure of the chemical potential for a redox reaction to occur (must be positive for the redox reaction to occur spontaneously).
I hope this helps :)
Voltage is the electrical potential energy difference between the cathode and the anode. Consequently, it is also a measure of the chemical potential for a redox reaction to occur (must be positive for the redox reaction to occur spontaneously).
I hope this helps :)
- Sun Feb 21, 2021 11:01 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt Bridge
- Replies: 30
- Views: 1488
Re: Salt Bridge
Hi, The salt bridge allows the reaction to continue occurring. As the redox reaction begins and the cathode gains more electrons, it loses its pulling ability, which could potentially stop the reaction from occurring. The salt bridge transfers negative ions to the anode and positive ions to cathode ...
- Tue Feb 16, 2021 2:30 pm
- Forum: Calculating Work of Expansion
- Topic: Textbook Excercise 4A.3
- Replies: 2
- Views: 296
Textbook Excercise 4A.3
Hi, Can someone explain how to do this problem because my answer is not matching the one in the textbook. 4A.3 Air in a bicycle pump is compressed by pushing in the handle. The inner diameter of the pump is 3.0 cm and the pump is depressed 20. cm with a pressure of 2.00 atm. (a) How much work is don...
- Mon Feb 15, 2021 4:58 pm
- Forum: Student Social/Study Group
- Topic: equipartition theorem
- Replies: 1
- Views: 175
equipartition theorem
Hi,
I saw the equipartition theorem described in our readings and was wondering if this equation and translational/rotational/vibrational energies will appear on the midterm.
Thanks beforehand for all your help :)
I saw the equipartition theorem described in our readings and was wondering if this equation and translational/rotational/vibrational energies will appear on the midterm.
Thanks beforehand for all your help :)
- Mon Feb 15, 2021 4:56 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Extra homework problems on Midterm 2
- Replies: 14
- Views: 844
Re: Extra homework problems on Midterm 2
Hi,
You can find all the homework problems that could appear on midterm 2 by looking at Dr Lavelle's syllabus and completing the problems stated under thermochemistry and thermodynamics.
I hope this helps :)
You can find all the homework problems that could appear on midterm 2 by looking at Dr Lavelle's syllabus and completing the problems stated under thermochemistry and thermodynamics.
I hope this helps :)
- Thu Feb 11, 2021 1:27 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Residual Entropy
- Replies: 1
- Views: 165
Re: Residual Entropy
Hi, Since all systems are not fully effective and there is no way for the system to reach 0K, everything in reality has some amount of residual entropy. I don't think there is exact cutoff for what is considered small since it depends on the data presented, but it is important to remember that the m...
- Thu Feb 11, 2021 1:24 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: deltaS total
- Replies: 2
- Views: 209
Re: deltaS total
Hi, Since in an isothermal reversible pathway the temperature remains constant, the system and the surroundings are considered to be at thermal equilibrium. As a result, DeltaS of systems equals 0. Furthermore, since an isothermal reversible pathway consists of infinitesimally small steps, the small...
- Thu Feb 11, 2021 1:18 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Balancing for Hess's Law
- Replies: 2
- Views: 288
Re: Balancing for Hess's Law
Hi, you use the whole number coefficients to balance the equation; however, for calculating entropy/enthalpy you need to see how many moles of the substance are involved in the reaction since you will have to divide or multiply accordingly depending on how you balance your chemical equation. I hope ...
- Thu Feb 11, 2021 11:40 am
- Forum: Calculating Work of Expansion
- Topic: Work
- Replies: 6
- Views: 408
Re: Work
Hi, Work done on an irreversible pathway tends to occur quickly and take less work since the system is pushing against a lower external pressure. On the other hand, the work done by a reversible pathway maximizes the amount of work performed by the system since the external pressure is almost exactl...
- Thu Feb 11, 2021 11:37 am
- Forum: Administrative Questions and Class Announcements
- Topic: Outline Progress
- Replies: 2
- Views: 169
Re: Outline Progress
Hi, During his office hours, Dr Lavelle confirmed that the midterm will include all of outline 3 remaining post midterm 1 and outline 4. As a result, I would assume we will finish outline 4 by tomorrow's lecture, since I am pretty certain that is the last lecture for the midterm. I hope this helps :)
- Sun Feb 07, 2021 8:32 pm
- Forum: Student Social/Study Group
- Topic: Midterm 2 study tips
- Replies: 26
- Views: 1505
Re: Midterm 2 study tips
Hi, As many others have said I would definitely recommend doing the problems listed on the outline and syllabus since those also appear on the exam. UA sessions and TA office hours can also be helpful if you have specific questions or topics you’d like to review. Lastly, the most helpful thing for m...
- Sun Feb 07, 2021 12:45 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Cv vs Cp
- Replies: 2
- Views: 142
Re: Cv vs Cp
Hi, Enthalpy means the amount of heat released or absorbed in a reaction at a constant pressure. Since Enthalpy, which equals DeltaH, requires a constant pressure, you can only solve for qp/ethanlpy when the system has a constant pressure. if the system has a constant volume rather than a constant p...
- Sun Feb 07, 2021 12:36 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: calorimeter
- Replies: 1
- Views: 182
Re: calorimeter
Hi, So for heat capacity of calorimeters, it is a constant for that piece of equipment, therefore we are not interested in the mass of a substance in the calorimeter. We know that q=mcdeltaT, but since for the calorimeter the heat capacity is the same no matter the mass we can disregard the m and yo...
- Sun Feb 07, 2021 12:33 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: HW Question
- Replies: 2
- Views: 183
Re: HW Question
Hi, The first thing you have to do is find the calorimetry heat capacity by using the equation q=mcdeltaT. In order to do that you put in the information found in the first sentence of the question and find the missing value c, which you can apply to the second half of the question since c is a cons...
- Sun Feb 07, 2021 12:29 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Sapling Question #9 Week 3/4
- Replies: 3
- Views: 619
Sapling Question #9 Week 3/4
Hi, I am confused on how to approach this question. I know we need to use the specific heat capacity of water but I am not sure exactly how. If you combine 420.0 mL of water at 25.00 ∘C and 130.0 mL of water at 95.00 ∘C, what is the final temperature of the mixture? Use 1.00 g/mL as the density of w...
- Thu Jan 28, 2021 6:03 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Significant Figures when Doing Ice Table Problems
- Replies: 3
- Views: 185
Re: Significant Figures when Doing Ice Table Problems
Hi! Dr Lavelle said we do not have to worry too much about sig figs for this course so I would recommend doing it with the most accurate values and then comparing it to answers in the question. My TA in discussion said that If your value varies slightly from one of the answer choices then to choose ...
- Thu Jan 28, 2021 5:59 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Polyprotic acids and bases
- Replies: 2
- Views: 211
Re: Polyprotic acids and bases
It was in the readings he assigned and it was included in some homework problems so I would say we do have to know how. However, during his office hours Dr Lavelle said that he would give us the Ka1 values for the problem and the Ka2 value if it was significant. The textbook says that only H2SO4 has...
- Tue Jan 26, 2021 2:28 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 4.31
- Replies: 1
- Views: 189
Re: 4.31
Hi,
For part B, you need to use the ideal gas law to find out how many moles of hydrogen you have and then from there you can multiply the amount of moles by the enthalpy change of the reaction (which is in per mole) to find your final answer.
Hope this helps :)
For part B, you need to use the ideal gas law to find out how many moles of hydrogen you have and then from there you can multiply the amount of moles by the enthalpy change of the reaction (which is in per mole) to find your final answer.
Hope this helps :)
- Tue Jan 26, 2021 2:14 pm
- Forum: Student Social/Study Group
- Topic: Midterm
- Replies: 2
- Views: 135
Re: Midterm
The midterm will be structured like last quarter and will all be multiple choice. There might be partial credit but I am not sure.
Hope this helps :)
Hope this helps :)
- Tue Jan 26, 2021 10:22 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Textbook Excercise 4D.15
- Replies: 3
- Views: 222
Textbook Excercise 4D.15
Hi,
I know how to approach 4D.15 in the textbook, but I keep getting the right answer with a positive sign where as the book labels it as -312KJ.mol^-1. Does anyone know what I might be doing wrong?
I attached the problem below.
thanks beforehand :)
I know how to approach 4D.15 in the textbook, but I keep getting the right answer with a positive sign where as the book labels it as -312KJ.mol^-1. Does anyone know what I might be doing wrong?
I attached the problem below.
thanks beforehand :)
- Sat Jan 23, 2021 3:28 pm
- Forum: Student Social/Study Group
- Topic: Lectures on Midterm
- Replies: 10
- Views: 571
Re: Lectures on Midterm
Hi,
Yes, all the lectures from week 1 to the end of week 3 are covered on the midterm. Week 4 lectures are not covered on the midterm.
Hope this helps :)
Yes, all the lectures from week 1 to the end of week 3 are covered on the midterm. Week 4 lectures are not covered on the midterm.
Hope this helps :)
- Sat Jan 23, 2021 3:27 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Homework number six
- Replies: 4
- Views: 272
Re: Homework number six
Hi In order to identify if a salt is acidic basic or neutral you have to break it apart into the anion and the cation. Then the key rule to remember is that the conjugate acids of weak bases make a salt acidic and the conjugate bases of weak acids make the sale basic. Based on these rules, you can t...
- Sat Jan 23, 2021 3:23 pm
- Forum: Student Social/Study Group
- Topic: Study Guide - Midterm?
- Replies: 14
- Views: 897
Re: Study Guide - Midterm?
Hi,
When I study for Chem midterms I have found it helpful creating a study guide based on the learning outcomes/outline points on Dr Lavelle's website. This way you can connect his lectures to our outlines which include the topics we will be tested on.
I hope this helps :)
When I study for Chem midterms I have found it helpful creating a study guide based on the learning outcomes/outline points on Dr Lavelle's website. This way you can connect his lectures to our outlines which include the topics we will be tested on.
I hope this helps :)
- Sat Jan 23, 2021 3:21 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Weak acids/ Weak Bases
- Replies: 3
- Views: 256
Re: Weak acids/ Weak Bases
Hi,
Strong bases include oxides and hydroxides of groups 1 and 2 metals and some of the strong acids include all the hydrogens bonded to halogens except hydrogen fluoride which is a weak acid.
Hope this helps :)
Strong bases include oxides and hydroxides of groups 1 and 2 metals and some of the strong acids include all the hydrogens bonded to halogens except hydrogen fluoride which is a weak acid.
Hope this helps :)
- Sat Jan 23, 2021 10:22 am
- Forum: Phase Changes & Related Calculations
- Topic: Phase Change
- Replies: 2
- Views: 200
Re: Phase Change
Hi,
For the enthalpy of formation, you can account for phase changes by adding the enthalpy required/released in that phase change to your enthalpy of formation calculations.
Hope this helps :)
For the enthalpy of formation, you can account for phase changes by adding the enthalpy required/released in that phase change to your enthalpy of formation calculations.
Hope this helps :)
- Sat Jan 23, 2021 10:20 am
- Forum: Phase Changes & Related Calculations
- Topic: Elements Not in standard state
- Replies: 5
- Views: 180
Re: Elements Not in standard state
Hi!
During Dr Lavelle's lecture he said we could account for compounds/elements not in the standard state by adding the enthalpy for the phase change required to put them in their standard state.
Hope this helps :)
During Dr Lavelle's lecture he said we could account for compounds/elements not in the standard state by adding the enthalpy for the phase change required to put them in their standard state.
Hope this helps :)
- Sat Jan 16, 2021 2:47 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Textbook Problem 6E.3
- Replies: 2
- Views: 193
Re: Textbook Problem 6E.3
Hi!
I think the cut off is like any other weak acid where Ka < 10^-4.
I hope this helps :)
I think the cut off is like any other weak acid where Ka < 10^-4.
I hope this helps :)
- Sat Jan 16, 2021 2:01 pm
- Forum: Administrative Questions and Class Announcements
- Topic: cannot login to sapling
- Replies: 4
- Views: 173
Re: cannot login to sapling
Hi,
I think you have to log onto sapling by first accessing CCLE and clicking on week 1 to open the website through the class website. When I did that the first day of the quarter, it let me apply me credit from last quarter and immediately enter the homework assignments.
I hope this helps :)
I think you have to log onto sapling by first accessing CCLE and clicking on week 1 to open the website through the class website. When I did that the first day of the quarter, it let me apply me credit from last quarter and immediately enter the homework assignments.
I hope this helps :)
- Sat Jan 16, 2021 1:59 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6B11
- Replies: 1
- Views: 153
Re: 6B11
Hi,
To solve part be you would use your answer for part i and then the equation M1V1 = M2V2 to determine the original hydroxide concentration before dilution.
I hope this helps :)
To solve part be you would use your answer for part i and then the equation M1V1 = M2V2 to determine the original hydroxide concentration before dilution.
I hope this helps :)
- Sat Jan 16, 2021 1:50 pm
- Forum: Ideal Gases
- Topic: Sapling Question #4
- Replies: 11
- Views: 585
Sapling Question #4
Hi, Can anyone help me with how to approach this problem? At a certain temperature, the given reaction has an equilibrium constant of Kp=393 PCl3(g)+Cl2(g) --> PCl5(g) PCl5 is placed in a sealed container at an initial pressure of 0.0250 bar . What is the total pressure at equilibrium? Thank you in ...
- Fri Jan 15, 2021 11:12 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6.19a
- Replies: 1
- Views: 168
Re: 6.19a
Hi,
I think in this scenario the lactic acid can also react with the HBO2 resulting in a lowering on the compounds concentration.
I hope this helps :)
I think in this scenario the lactic acid can also react with the HBO2 resulting in a lowering on the compounds concentration.
I hope this helps :)
- Fri Jan 15, 2021 11:07 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Week 2 Sapling Homework - Question #1
- Replies: 3
- Views: 242
Re: Week 2 Sapling Homework - Question #1
Hi! For this problem you would want to first write a balanced chemical equation followed by making an ICE table. Afterwards, using the values in your ice table you can fill in the concentrations and set them equal to your Ka value. After you find what x equals, you can use it to identify your hydron...
- Sun Jan 10, 2021 12:06 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Audio and Visual Focus Chemical Equilibrium Part 4 Question 14
- Replies: 2
- Views: 161
Re: Audio and Visual Focus Chemical Equilibrium Part 4 Question 14
Hi, yes your reasoning is exactly correct. A decrease in SO3 through condensation will result in more product being formed to minimize the effect of the change resulting in both of the reactants reacting to form BOTH SO3 and NO resulting in an increase of NO compared to its initial value. I hope thi...
- Sun Jan 10, 2021 12:03 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Audio and Visual Focus Chemical Equilibrium Part 4 Question 13
- Replies: 2
- Views: 128
Re: Audio and Visual Focus Chemical Equilibrium Part 4 Question 13
Hi, Your reasoning for part II is completely correct. Since the reaction is exothermic, by decreasing the temperature the reaction favors the side with a lower enthalpy which in this case is the products. Regarding part I, when the volume is decreased (pressure is applied/increases) the reaction wil...
- Thu Jan 07, 2021 8:39 pm
- Forum: Ideal Gases
- Topic: Chemical Equilibrium Part 1A Post-Module Assessment
- Replies: 4
- Views: 289
Re: Chemical Equilibrium Part 1A Post-Module Assessment
Hi, The answer to this would be D since even though the reaction has reached equilibrium it is impossible for the reaction itself to stop occurring naturally if possible. However, since at equilibrium the forward and reverse reactions occur at the same rate the concentrations of the reactants and pr...
- Mon Jan 04, 2021 9:11 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Part 2 module review #19
- Replies: 3
- Views: 219
Re: Part 2 module review #19
Yes exactly! Solids/liquids which are pure substances are not included in the calculation of k.
hope this helps :)
hope this helps :)
- Mon Jan 04, 2021 9:10 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Liquid (pure substance) vs Aqueous
- Replies: 2
- Views: 249
Re: Liquid (pure substance) vs Aqueous
Hi!
Yes that is exactly correct! Furthermore, since water, the solvent, is a pure substance (liquid) it is not included in the calculation of K.
I hope this helps :)
Yes that is exactly correct! Furthermore, since water, the solvent, is a pure substance (liquid) it is not included in the calculation of K.
I hope this helps :)
- Thu Dec 10, 2020 7:16 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Why is NH2 a bidentate ligand?
- Replies: 2
- Views: 1527
Re: Why is NH2 a bidentate ligand?
Hi,
NH2 is a monodentate ligand. However the ligand in the photo, is not only NH2 it consists of two NH2 molecules which are part of the whole ligand and provide the two lone pairs. Therefore, not NH2 but the whole ligand containing two NH2 compounds is bidentate.
I hope this helps :)
NH2 is a monodentate ligand. However the ligand in the photo, is not only NH2 it consists of two NH2 molecules which are part of the whole ligand and provide the two lone pairs. Therefore, not NH2 but the whole ligand containing two NH2 compounds is bidentate.
I hope this helps :)
- Thu Dec 10, 2020 7:13 pm
- Forum: Photoelectric Effect
- Topic: Work function?
- Replies: 1
- Views: 269
Re: Work function?
Hi, Just like you wrote, you can find the work function if the minimum frequency needed to remove an electron is given in the problem.Likewise, if the problem gives you the threshold energy (work function) needed to remove an electron you can calculate the threshold frequency by using the equation E...
- Thu Dec 10, 2020 7:10 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: AX3E2
- Replies: 7
- Views: 655
Re: AX3E2
Hi, For AX3E2 the central atom has five regions of electron density. Therefore, its electron arrangement must be trigonal bipyramidal. When choosing the lone pairs you have to choose lone pairs that minimize electron pair repulsions. By placing our lone pairs in the equatorial position, it minimizes...
- Thu Dec 10, 2020 6:57 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Metals and ligands
- Replies: 1
- Views: 72
Re: Metals and ligands
Hi,
Ligands are lewis bases which donate an electron pair to the central metal atom. Each ligand can consist of one or electron density regions of the central atom depending on if it is polydentate or not.
I hope this helps! :)
Good luck studying for the final!
Ligands are lewis bases which donate an electron pair to the central metal atom. Each ligand can consist of one or electron density regions of the central atom depending on if it is polydentate or not.
I hope this helps! :)
Good luck studying for the final!
- Thu Dec 10, 2020 6:54 pm
- Forum: Properties of Light
- Topic: What are the ranges of wavelength for each type of electromagnetic radiation?
- Replies: 5
- Views: 472
Re: What are the ranges of wavelength for each type of electromagnetic radiation?
Hi, I don't think we need to know the exact ranges of each type of EM radiation, other than visible light which has wavelengths between 400nm to 700nm. However, I think we do have to know how the order of the EM spectrum so we can compare which type of light has a shorter wavelength/high frequency. ...
- Thu Dec 10, 2020 6:49 pm
- Forum: Student Social/Study Group
- Topic: Katherine Estoque acids/bases review
- Replies: 1
- Views: 180
Re: Katherine Estoque acids/bases review
Hi!
She had her review session on acids and bases today and she posted her slides. I've attached them here too just in case you still can't find them
I found her slides really helpful!
She had her review session on acids and bases today and she posted her slides. I've attached them here too just in case you still can't find them
I found her slides really helpful!
- Sat Dec 05, 2020 11:34 pm
- Forum: Bronsted Acids & Bases
- Topic: Acids strong vs not
- Replies: 3
- Views: 326
Re: Acids strong vs not
Hi! The relative strength of an acid is determined by how easily the acid can lose an H atom as well as how stable the resulting anion becomes (depending on if resonance exists and the electronegativity/electron pulling power of the anion). Using these two criteria you can determine which acid is st...
- Sat Dec 05, 2020 11:31 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Oxidation Number
- Replies: 4
- Views: 388
Re: Oxidation Number
Hi
I found this sapling link with oxidation number rules really helpful!
https://sites.google.com/site/chempendix/oxidation
I found this sapling link with oxidation number rules really helpful!
https://sites.google.com/site/chempendix/oxidation
- Wed Dec 02, 2020 5:52 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Number
- Replies: 2
- Views: 180
Re: Coordination Number
Hi!
The coordination number of the complex compound reflects how many ligands the TM is bonded to.
I hope this helps :)
The coordination number of the complex compound reflects how many ligands the TM is bonded to.
I hope this helps :)
- Wed Dec 02, 2020 9:50 am
- Forum: Biological Examples
- Topic: Enzyme Function
- Replies: 9
- Views: 580
Re: Enzyme Function
Hi,
Transition metals are located in the active site of the enzyme and help the molecules bond to the enzyme.
I hope this helps :)
Transition metals are located in the active site of the enzyme and help the molecules bond to the enzyme.
I hope this helps :)
- Sun Nov 29, 2020 9:49 am
- Forum: Biological Examples
- Topic: Hemoglobin: a coordination compound?
- Replies: 2
- Views: 266
Re: Hemoglobin: a coordination compound?
Hi,
An organometallic compounds refers to ligands bound to carbon/carbon being a central part of the compound since any organic molecule must include carbons.
I hope this helps :)
An organometallic compounds refers to ligands bound to carbon/carbon being a central part of the compound since any organic molecule must include carbons.
I hope this helps :)
- Sun Nov 29, 2020 9:47 am
- Forum: General Science Questions
- Topic: Electron Affinity
- Replies: 4
- Views: 195
Re: Electron Affinity
Hi, Although in the lectures Dr Lavelle did not give us the exact electron affinities for noble gases, he said that all noble gases have negative electron affinities since they do not release energy when an electron is added but rather they require energy for an electron to be added. I hope this hel...
- Wed Nov 25, 2020 5:19 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Ni (NH3)2 Cl2 example from Lecture
- Replies: 1
- Views: 191
Re: Ni (NH3)2 Cl2 example from Lecture
Hi!
Nickel 2+ can have enough room for the bonds since it also has an empty p-shell it can utilize if necessary.
I hope this helps :)
Nickel 2+ can have enough room for the bonds since it also has an empty p-shell it can utilize if necessary.
I hope this helps :)
- Wed Nov 25, 2020 5:13 pm
- Forum: Hybridization
- Topic: Hybridization Explanation
- Replies: 6
- Views: 391
Re: Hybridization Explanation
Hi!
Hybridization occurs as molecules come closer together and begin to form bonds. As atoms come closer together, the electron density of the atoms shift/change in order to allow the optimal amount of bonds necessary for the compound to form.
I hope this helps :)
Hybridization occurs as molecules come closer together and begin to form bonds. As atoms come closer together, the electron density of the atoms shift/change in order to allow the optimal amount of bonds necessary for the compound to form.
I hope this helps :)
- Wed Nov 25, 2020 5:10 pm
- Forum: Naming
- Topic: Ethylene Diamine Tetra Acetate
- Replies: 6
- Views: 380
Re: Ethylene Diamine Tetra Acetate
Hi,
Dr. Lavelle said in today's lecture that we will go over naming, but since we haven't yet I don't think you need to know it until he covers it during lecture.
I hope this helps :)
Dr. Lavelle said in today's lecture that we will go over naming, but since we haven't yet I don't think you need to know it until he covers it during lecture.
I hope this helps :)
- Wed Nov 18, 2020 9:12 pm
- Forum: Bond Lengths & Energies
- Topic: textbook 2.27
- Replies: 2
- Views: 279
Re: textbook 2.27
Hi,
in these cases I would look at the size of each individual atom since the larger the atom the longer the bond length. You can use the trends of ionic/atomic radii to determine which atom is larger.
I hope this helps :)
in these cases I would look at the size of each individual atom since the larger the atom the longer the bond length. You can use the trends of ionic/atomic radii to determine which atom is larger.
I hope this helps :)
- Wed Nov 18, 2020 9:09 pm
- Forum: Bond Lengths & Energies
- Topic: Comparing Strengths of Interactions Between Ions
- Replies: 2
- Views: 246
Re: Comparing Strengths of Interactions Between Ions
Hi,
When solving this problem, I would first look at the size/charge of the cation and anion respectively. A smaller sized cation with a greater positive charge will lead to stronger ionic character, thus making the answer to this question CAO rather than KCL.
When solving this problem, I would first look at the size/charge of the cation and anion respectively. A smaller sized cation with a greater positive charge will lead to stronger ionic character, thus making the answer to this question CAO rather than KCL.
- Wed Nov 18, 2020 9:07 pm
- Forum: Octet Exceptions
- Topic: Textbook Problem 2C.1
- Replies: 2
- Views: 160
Re: Textbook Problem 2C.1
Hi,
When approaching this problem, I would first draw out the lewis structures and from there you can see if any atom in each molecule has an unpaired electron, which would make it a radical.
I hope this helps :)
When approaching this problem, I would first draw out the lewis structures and from there you can see if any atom in each molecule has an unpaired electron, which would make it a radical.
I hope this helps :)
- Wed Nov 18, 2020 9:05 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR Notation
- Replies: 3
- Views: 218
Re: VSEPR Notation
Hi! The central atom is always the least electronegative and in this example it is carbon. Since Carbon in CH3CL is bonded to each atom, the molecule consequently has 4 bonding regions with no extra electrons/lone pairs. Therefore, its VSEPR notation must be AX4 since the structure describes a centr...
- Mon Nov 16, 2020 10:57 am
- Forum: Dipole Moments
- Topic: Dipole Moment
- Replies: 7
- Views: 419
Re: Dipole Moment
Hi,
All molecules can have instantaneous dipole moments that only last temporarily since electrons continuously move in the molecule. Therefore, while CO2, like all other nonpolar molecules, may not have a permanent dipole and it has instantaneous dipoles that are constantly changing.
All molecules can have instantaneous dipole moments that only last temporarily since electrons continuously move in the molecule. Therefore, while CO2, like all other nonpolar molecules, may not have a permanent dipole and it has instantaneous dipoles that are constantly changing.
- Mon Nov 16, 2020 10:54 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lecture 11/16 SO3 (2-) example
- Replies: 4
- Views: 818
Re: Lecture 11/16 SO3 (2-) example
Hi, By stating that the molecule is arranged tetrahedrally, he references how the shape of the molecule shows a central atom(in his case sulfur) surrounded by 4 regions of electron density. However, although the shape consists of those four regions, when we name the shape of the molecule we only ref...
- Thu Nov 12, 2020 5:57 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: angular momentum equation
- Replies: 2
- Views: 177
angular momentum equation
Hi,
I was reading the textbook and saw that there was an angular momentum equation. Do we need to know that for the midterm or will we not be tested on it?
Thank you so much beforehand :)
I was reading the textbook and saw that there was an angular momentum equation. Do we need to know that for the midterm or will we not be tested on it?
Thank you so much beforehand :)
- Thu Nov 12, 2020 1:42 pm
- Forum: Ionic & Covalent Bonds
- Topic: Textbook 2A19
- Replies: 2
- Views: 169
Re: Textbook 2A19
Hi! You can predict the number of valance electrons based on the atom's placement in the periodic table as well as based on whether it is more likely to accept or lose its electrons. For instance, Oxygen, which is in group sixteen of the periodic naturally has six valence electrons, and becomes an O...
- Thu Nov 12, 2020 1:37 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Oxidation Number
- Replies: 4
- Views: 408
Re: Oxidation Number
Hi!
I attached the link with the rules to finding oxidation numbers that sapling created. I hope this helps :)
https://sites.google.com/site/chempendix/oxidation
I attached the link with the rules to finding oxidation numbers that sapling created. I hope this helps :)
https://sites.google.com/site/chempendix/oxidation
- Thu Nov 12, 2020 1:35 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: sapling q 13
- Replies: 3
- Views: 7094
Re: sapling q 13
Hi! You are right that the four hydrogens connected to the nitrogens could create a hydrogen bond with water. However additionally, the two nitrogens each have one set of lone pairs and the oxygen molecule has two lone pairs open for hydrogen bonding. Thus, the maximum number of water molecules that...
- Sun Nov 08, 2020 7:43 pm
- Forum: Ionic & Covalent Bonds
- Topic: Comparing Two Elements' Electronegativities
- Replies: 3
- Views: 166
Re: Comparing Two Elements' Electronegativities
Hi, In his lecture Dr. Lavelle explained that when the difference is between 1.5-2 we would have to look at how the compound actually behaves in experiments such as its ability to dissolve in water in order to identify whether the compound acts more as an ionic or covalent bond. I hope this helps :)
- Sun Nov 08, 2020 7:41 pm
- Forum: Lewis Structures
- Topic: Lewis Acids/Bases
- Replies: 4
- Views: 357
Re: Lewis Acids/Bases
Hi!
A lewis acid is electron deficient meaning it needs a lone pair of electrons in order to complete its octet. On the other hand, a lewis base has enough electrons to complete its octet and can share one of its lone pairs with the lewis acid.
I hope this helps :)
A lewis acid is electron deficient meaning it needs a lone pair of electrons in order to complete its octet. On the other hand, a lewis base has enough electrons to complete its octet and can share one of its lone pairs with the lewis acid.
I hope this helps :)
- Thu Nov 05, 2020 1:03 pm
- Forum: General Science Questions
- Topic: Midterm Grades
- Replies: 30
- Views: 1506
Re: Midterm Grades
Marley Magee 2H wrote:Does anyone know where they'll be posted? Just under grades on CCLE, right?
Hi!
Yes Dr. Lavelle said they will be posted on CCLE under grades. I hope this helps :)
- Thu Nov 05, 2020 1:01 pm
- Forum: Lewis Structures
- Topic: Lewis Structure Question
- Replies: 4
- Views: 269
Re: Lewis Structure Question
Hi, One of the limitations in lewis structures is that they do not reflect bond length or resonance (when each bond length is between a single and double bond). When discussing the bond length, it depends on which atoms are bonding to each other as well as if there is resonance in the compound. Thus...
- Thu Nov 05, 2020 12:57 pm
- Forum: *Shrodinger Equation
- Topic: Shrodinger Equation Explanation
- Replies: 3
- Views: 365
Re: Shrodinger Equation Explanation
Hi! The schrodinger equation is meant to explain the movement of an electron around an orbital, which can be described through many different functions since each electron behaves differently. When you take the double derivative of the wave function which is the hamiltonian (H) you get the wave func...
- Mon Nov 02, 2020 3:25 pm
- Forum: General Science Questions
- Topic: Midterm Grades
- Replies: 30
- Views: 1506
Re: Midterm Grades
When will our final grades from the midterm be posted? Also, I heard someone say Lavelle may be offering partial credit? How would that be the case because they are multiple choice? Hi! I am in Dr. Lavelle's office hours and he said that all grades including chemistry community should be updated by...
- Sun Nov 01, 2020 5:41 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Explaining Quantum Numbers
- Replies: 2
- Views: 183
Re: Explaining Quantum Numbers
Hi! Since quantum numbers represent a certain a state for the electron, knowing the electron configuration you'd have to know which shell/subshell the question was referring to so you could write the correct quantum numbers for that state. Once you know which state you referring to you can decipher ...
- Sun Nov 01, 2020 5:27 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Resources for quantum numbers
- Replies: 3
- Views: 278
Re: Resources for quantum numbers
Hi! Quantum numbers were a little confusing for me as well when I first watched the lecture. But afterwards, I watched a khan academy video on it which really helped me fully comprehend quantum numbers and electron configurations. I've attached the video below so you can watch it. I definitely recom...
- Sun Nov 01, 2020 5:23 pm
- Forum: Trends in The Periodic Table
- Topic: Second ionization energy
- Replies: 3
- Views: 187
Re: Second ionization energy
Hi! The second ionization energy is always higher than the first one since when the atom loses an electron is has a net positive charge. Consequently, when something has a net positive charge the nuclear charge increases holding the electrons more tightly towards the nucleus. As a result of this inc...
- Sun Nov 01, 2020 4:06 pm
- Forum: Trends in The Periodic Table
- Topic: Isoelectronic atoms/ions Radii
- Replies: 1
- Views: 132
Isoelectronic atoms/ions Radii
Hi! When I was watching the lecture regarding trends in the periodic table, I noticed that the radii of isoelectronic particles such as O2- and F- still have a big difference in their ionic radius. I was wondering why this was so since they have the same number of electrons? Is this because of how t...
- Thu Oct 29, 2020 10:39 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Outline 2 Topic Confusion
- Replies: 2
- Views: 182
Re: Outline 2 Topic Confusion
Hi, I think the first sentence refers to describing the shape of the orbitals, how many subshells of the orbitals there are and any other descriptions of the orbital in general. And the second sentence refers to the relationship amongst the orbitals themselves and how they affect the electron's beha...
- Tue Oct 27, 2020 12:47 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Limit on delta x?
- Replies: 1
- Views: 169
Limit on delta x?
Hi, I hope all is well. I just watched the audio-visual focus module on the heisenberg indeterminacy equation and noticed that Dr. Lavelle said that the delta v (uncertainty in velocity) must be less than the speed of light. Thus, I was also wondering if there was a limit on the uncertainty in posit...
- Fri Oct 23, 2020 8:44 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Sapling #13
- Replies: 1
- Views: 148
Re: Sapling #13
Hi! In this question, the -1 refers to how many orbitals of the subshell f there are. Since our l value is 3, we know that our ml values can be any integer from -3 to 3. Therefore, the -1 part of this problems reflects that you have three orbitals(-3,-2, and -1) of the f suborbital on shell 6. Knowi...
- Fri Oct 23, 2020 4:02 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Electron Density Distribution
- Replies: 8
- Views: 432
Re: Electron Density Distribution
Hi,
The electron density distribution refers to the arrangement of the electrons in atom (and the probability of finding the electron at that certain space).
I hope this helps :)
The electron density distribution refers to the arrangement of the electrons in atom (and the probability of finding the electron at that certain space).
I hope this helps :)
- Wed Oct 21, 2020 3:25 pm
- Forum: *Particle in a Box
- Topic: Midterm 1
- Replies: 17
- Views: 1461
Re: Midterm 1
Hi! We will not be tested on the particle in a box on the midterm. Dr Lavelle said in his lecture today that our midterm will only go up to the last slide he did which introduced the different atomic orbitals and did not discuss a particle in a box. In general, our midterm will only contain all the ...
- Wed Oct 21, 2020 3:20 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: S Orbitals and nodal planes
- Replies: 5
- Views: 315
S Orbitals and nodal planes
Hi! When comparing the different types of orbitals Dr. Lavelle mentioned that the s orbital unlike the others has no nodal plane and a symmetric electron density distribution. Does this then mean that there is no point in the s orbital for which we get an electron density distribution of 0? Furtherm...
- Wed Oct 21, 2020 3:11 pm
- Forum: *Shrodinger Equation
- Topic: Schrodinger Equation, H
- Replies: 2
- Views: 165
Re: Schrodinger Equation, H
Hi! H in Schrodinger's equation is called the Hamiltonian and refers to the double derivative of the wave function(psi). This equation is thus stating that the double derivative of the wave function will show us (be equal to) the mathematical wave function of the electron's energy. I hope this helps!
- Sat Oct 17, 2020 2:18 pm
- Forum: Student Social/Study Group
- Topic: How are you studying?
- Replies: 204
- Views: 24877
Re: How are you studying?
Hi! Here are a couple of things that help me. When watching the lecture, I make sure to take detailed notes and pause the video when needed. When we finish a certain topic in a video I also pause the video and try to write down or verbally explain the topic to myself in order to test what I actually...
- Fri Oct 16, 2020 3:43 pm
- Forum: Properties of Electrons
- Topic: Atomic Spectra Lecture
- Replies: 2
- Views: 201
Re: Atomic Spectra Lecture
Hi! In the example in the lecture light was emitted by the hydrogen atom, meaning that the electron lost energy resulting not only in it decreasing its principal quantum level from 4 to 2 but also experiencing a negative change in energy. However, if the opposite was occurring and the electron was b...
- Fri Oct 16, 2020 3:18 pm
- Forum: Properties of Electrons
- Topic: Wave Properties of Electrons
- Replies: 4
- Views: 135
Re: Wave Properties of Electrons
Hi! When explaining that waves cancel each other out, Professor Lavelle is referring to the destructive interference of waves, which occurs when waves interact with one another out of phase. When this occurs, a photo of the resulting wave will look shorter since the overlap of the two waves cancel e...
- Fri Oct 16, 2020 3:10 pm
- Forum: Properties of Light
- Topic: Textbook Excercise A1.3
- Replies: 3
- Views: 134
Textbook Excercise A1.3
Hi! When figuring out the answer I could deduce that C was the correct answer but I am not completely sure on why C is correct. Can someone explain this to me in more detail? Which of the following happens when the frequency of electromagnetic radiation decreases? Explain your reasoning. (a) The spe...