Search found 101 matches
- Mon Mar 16, 2020 3:53 pm
- Forum: Administrative Questions and Class Announcements
- Topic: final grades
- Replies: 12
- Views: 1023
Re: final grades
In addition to being able to see our grades, does anyone also know if we will be able to review our answers? I would like to see the questions I got wrong. How will we be able to see these? Is he releasing the final exams online? We'll be able to see specifically what we missed because we took the ...
- Sat Mar 14, 2020 1:27 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Saying Thank You to Dr. Lavelle
- Replies: 490
- Views: 516893
Re: Saying Thank You to Dr. Lavelle
Dr. Lavelle, thank you for taking care of us throughout the whole quarter. I admire how quickly you acted to make sure we would be assessed as fairly as possible during these chaotic times, and I really appreciate how selfless you are when you take so much time out of your own day to organize study ...
- Sat Mar 14, 2020 11:10 am
- Forum: Administrative Questions and Class Announcements
- Topic: 1G,1H,1I Discussion, Echem Review
- Replies: 1
- Views: 588
Re: 1G,1H,1I Discussion, Echem Review
For Number 1 on Test 2, why would you not multiple S or H by 2, because you need to balance the equation first and that doubles the moles of product?
- Sat Mar 14, 2020 10:59 am
- Forum: Administrative Questions and Class Announcements
- Topic: Format?
- Replies: 11
- Views: 826
Re: Format?
Do we need a printer? I can't imagine doing Chem through my laptop.
- Sat Mar 14, 2020 10:57 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Hw 6N.3 a)
- Replies: 2
- Views: 276
Re: Hw 6N.3 a)
So from the cell diagram, we know that the anode on the left is the oxidation half-reaction and the cathode on the right is the reduction half-reaction. For the oxidation half-reaction we have two species they give you, H 2 (g) and HCl (aq). In this case, since HCl is aqueous, you can think of it a...
- Tue Mar 10, 2020 5:27 pm
- Forum: Administrative Questions and Class Announcements
- Topic: HW10
- Replies: 3
- Views: 375
Re: HW10
Yes, I would probably do homework on kinetics for this week.
- Sun Mar 08, 2020 11:34 pm
- Forum: First Order Reactions
- Topic: 7B.17b
- Replies: 2
- Views: 207
7B.17b
Calculate the time required for each of the following second-order reactions to take place: (b)A->2B + C,when [A]0 = 0.15 mol/L, for the concentration of B to increase to 0.19 mol/L, given that kr = 0.0035 L/mol.min in the rate law for the loss of A. Why does the solutions manual include the part wh...
- Sun Mar 08, 2020 11:25 pm
- Forum: Student Social/Study Group
- Topic: Final Jitters
- Replies: 457
- Views: 336741
Re: Final Jitters
I think one should cram (if you must cram) the full day/night two days before the final and then take it easy the day before; sleep and have a good meal and just review lightly in the 24 hours before the final!
- Sun Mar 08, 2020 10:56 pm
- Forum: General Rate Laws
- Topic: 7B7cd
- Replies: 1
- Views: 201
7B7cd
Substance A decomposes in a first-order reaction and its half life is 355 s. How much time must elapse for the concentration of A to decrease to ... (c) 15% of its initial concentration; (d) one-ninth of its initial concentration? Why does the solutions manual do the math differently for each step. ...
- Sun Mar 08, 2020 10:34 pm
- Forum: General Rate Laws
- Topic: 7B5a
- Replies: 1
- Views: 182
7B5a
Dinitrogen pentoxide, N2O5, decomposes by first-order kinetics with a rate constant of 3.7 x 10^-5 /s at 298 K. (a) What is the half-life (in hours) of N2O5 at 298 K?
I am somewhat confused by how the units cancel. Why are the seconds applied to ln2 (numerator) and not the 3.7x10^-5 (denominator)?
I am somewhat confused by how the units cancel. Why are the seconds applied to ln2 (numerator) and not the 3.7x10^-5 (denominator)?
- Sun Mar 08, 2020 10:18 pm
- Forum: General Rate Laws
- Topic: 7B3a
- Replies: 3
- Views: 309
7B3a
Determine the rate constant for each of the following first- order reactions, in each case expressed for the rate of loss of A: (a) A -> B, given that the concentration of A decreases to one-half its initial value in 1000. s Answer: k=0.693/1000s Where did the solutions manual get the 0.693? There w...
- Sat Feb 29, 2020 3:57 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Possible Solution Error on 6N.1 part b
- Replies: 5
- Views: 402
Re: Possible Solution Error on 6N.1 part b
I agree, after asking a UA, we both agreed that there was an error in the solutions because the number of electrons only changes by one in the reduction.
- Sat Feb 29, 2020 3:56 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Concentration Cells and Nernst Equation
- Replies: 4
- Views: 317
Concentration Cells and Nernst Equation
What other situations makes use of the Nernst Equation (for our purposes in this class)? Would you only use it when given a concentration cell?
- Wed Feb 26, 2020 1:06 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Drawing Cell Diagrams
- Replies: 1
- Views: 185
Drawing Cell Diagrams
When you have multiple of one state of matter, does it matter the order in which you put them with the commas?
- Mon Feb 24, 2020 11:34 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6M5
- Replies: 1
- Views: 197
6M5
In the cell diagram for part (a) in the solutions manual, they do not include Pt(s) on the left side, but it is present on the right side. I thought Pt(s) had to be present on both sides, can someone explain why this happens?
- Mon Feb 24, 2020 11:31 pm
- Forum: Balancing Redox Reactions
- Topic: Explain the charges in this reaction
- Replies: 1
- Views: 171
Explain the charges in this reaction
2Hg^(2+) + 2e- --> . Hg2 ^(2+) (see image for clarification)
Can someone explain how this reaction works? I cannot figure out where the 2 e- come in since it seems to me like Hg keeps the same charge.
Can someone explain how this reaction works? I cannot figure out where the 2 e- come in since it seems to me like Hg keeps the same charge.
- Tue Feb 18, 2020 9:30 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Arrhenius equation?
- Replies: 2
- Views: 496
Arrhenius equation?
I was reading 5J3 and there was a box on page 432 that explained the changes on equilibrium constant of temperature. They explained through kinetics and mentioned the Arrhenius equation. Can someone explain what this all means?
- Tue Feb 18, 2020 6:41 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Basic Solutions
- Replies: 2
- Views: 245
Re: Balancing Basic Solutions
You would start balancing the Oxygen atoms by adding H2O on one side, but then you need to balance the Hydrogens. For basic solutions, there is a surplus of OH- compared to H+ in acidic solutions, so you would then add OH- to balance the Hydrogens.
- Tue Feb 18, 2020 6:25 pm
- Forum: Balancing Redox Reactions
- Topic: Understanding Half-Reactions
- Replies: 11
- Views: 669
Understanding Half-Reactions
Can someone explain why we use half-reactions? Dr. Lavelle said it makes it easier to understand the redox reaction as a whole but I am just more confused.
- Tue Feb 18, 2020 6:21 pm
- Forum: Van't Hoff Equation
- Topic: HW for this week?
- Replies: 1
- Views: 214
HW for this week?
What section of the textbook should we do for this week? The syllabus points us to 5G but I can't find the Van't Hoff Equation there.
- Tue Feb 18, 2020 6:18 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: midterm question// Concentration ratio [ENDORSED]
- Replies: 9
- Views: 686
Re: midterm question// Concentration ratio [ENDORSED]
What I did was I found Ka and used the pH given to find the concentration of H+. Since the equation for Ka is [H+][A-]/[HA], you can find the ratio of conjugate base to acid by dividing Ka by the concentration of H+. But how would you know if it stays as a salt in the stomach or becomes something e...
- Tue Feb 11, 2020 9:10 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Pizza Rolls 10
- Replies: 4
- Views: 386
Re: Pizza Rolls 10
I did it the way you advised and still got 22.85C as my answer for Tf. For your Step 3, shouldn't the right side of the equation be negative (e.g. -265 g*specific heat of water...)? Why do you not use the specific heat of ice on the right side? (Using the specific heat of ice gives me 20.93C for my ...
- Tue Feb 11, 2020 6:58 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Pizza Rolls 10
- Replies: 4
- Views: 386
Pizza Rolls 10
10: Matt asks me for water with no ice at a dining hall. Just to spite him, I measure 25.0 g of ice at 0.00 oC and drop it into 265 mL of water at 25.0 oC. What is the final temperature of the water?
Can someone provide a step-by-step guide on how to solve this?
Can someone provide a step-by-step guide on how to solve this?
- Tue Feb 11, 2020 6:29 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Pizza Rolls 6
- Replies: 3
- Views: 246
Re: Pizza Rolls 6
I also can't get the answer for q and w; it seems like he subtracted 23.3 and 9.12 to get 14.2, but I don't understand why you wouldn't add the work values you get for each part of the problem together instead. Edit: it seems that work will be positive if the system is being compressed, like in the ...
- Tue Feb 11, 2020 4:51 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Pizza Rolls 4
- Replies: 1
- Views: 174
Pizza Rolls 4
Can someone walk me through how to solve 4A of Pizza Rolls? I am confused about how to use Hess's Law.
- Tue Feb 11, 2020 4:37 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Pizza Rolls REVIEW Session DOWNLOAD HERE
- Replies: 67
- Views: 5547
Re: Pizza Rolls REVIEW Session DOWNLOAD HERE
3 E and 3 F Can someone explain why these two statements are false? I don't really understand the wording of 3E, and is it ever possible to have a negative heat capacity? 3E: Removing heat from a system is exothermic, so temperature must decrease. 3F: Heat Capacities can be negative for simple molec...
- Sun Feb 09, 2020 10:39 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: q rev
- Replies: 4
- Views: 271
Re: q rev
In terms of homework or test problems, they will most likely tell you explicitly that the system is being changed reversibly.
- Sun Feb 09, 2020 10:37 pm
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: Error in Boltzmann Equation
- Replies: 4
- Views: 261
Re: Error in Boltzmann Equation
What is the significance of having error in either the W or the S?
- Sun Feb 09, 2020 6:05 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 4F.1a
- Replies: 4
- Views: 146
Re: 4F.1a
Hi Amy Xiao 1I! To answer your question, the question is asking for the rate at which entropy is generated. Rate is typically some value per unit of time. For example, we have MPH, the rate of how far you're traveling (miles) per unit of time (hour). Because we want the rate of entropy generated, w...
- Tue Feb 04, 2020 12:40 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: 4F17
- Replies: 1
- Views: 110
4F17
Calculate the standard entropy of vaporization of water at 85C, given that its standard entropy of vaporization at 100C is 109.0 J/Kmol and the molar heat capacities at constant pressure of liquid water and water vapor are 75.3 J/Kmol and 33.6 J/Kmol, respectively, in this range. Why is it necessary...
- Tue Feb 04, 2020 12:09 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 4F.1a
- Replies: 4
- Views: 146
4F.1a
In the solutions manual for 4F.1a, why does it say that the rate of entropy generation is Entropy(of surroundings)/time? What does time have to do with this problem?
- Sun Feb 02, 2020 11:30 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimeter
- Replies: 5
- Views: 268
Re: Calorimeter
Areena H 2K wrote:From lecture, we talked about a bomb calorimeter which is an isolated system and insulation, and also an open calorimeter, and adiabatic calorimeters as well.
I don't remember Dr. Lavelle mentioning adiabatic calorimeters, can you explain what those are and their importance?
- Sun Feb 02, 2020 11:29 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: qp = ΔH?
- Replies: 5
- Views: 320
Re: qp = ΔH?
Remember that the definition of enthalpy is the change in heat at a constant pressure.
- Wed Jan 29, 2020 9:28 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 4D.9
- Replies: 2
- Views: 160
Re: 4D.9
I agree with Justin, I think that since you are dividing by a volume/density, which always has to be positive, you have to get a positive answer.
- Wed Jan 29, 2020 9:18 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 4D1
- Replies: 2
- Views: 158
Re: 4D1
The way the solutions manual solves it is that it first converts the 197 g of Carbon to mols -> 16.40 mol C. It also divides the energy absorbed by 4 moles of Carbon by 4 so that you will know how much 1 mol Carbon absorbs. After that, you can just multiply that energy by however many moles of carbo...
- Wed Jan 29, 2020 9:11 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 4D.7: Finding change in internal energy through ideal gas equation
- Replies: 4
- Views: 280
Re: 4D.7: Finding change in internal energy through ideal gas equation
Because the change in thermal energy is equal to q + w and since there isn't any work being done on the system, I believe that the answer is simply delta U = q and q = delta H so the answer is -320 because that is the value of delta H in the reaction for 1 mol of OF2. Where did you get the 320? The...
- Sun Jan 26, 2020 9:32 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3040312
Re: Post All Chemistry Jokes Here
Who is Gibbs, and why is he giving out free energy?
- Sun Jan 26, 2020 9:27 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3040312
Re: Post All Chemistry Jokes Here
Silver walks up to Gold in a bar and says, "AU, get outta here!"
- Sun Jan 26, 2020 9:24 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Week 4 Homework
- Replies: 11
- Views: 320
Week 4 Homework
What homework problem sets should we be doing for this week on enthalpy?
- Sun Jan 26, 2020 9:22 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard Reaction Enthalpy
- Replies: 3
- Views: 148
Re: Standard Reaction Enthalpy
If the bond enthalpies are not available you can calculate the standard reaction enthalpy using the standard enthalpy of formation of all products and subtracting that from the standard enthalpy of formation of all reactants. To add on to that, Dr. Lavelle talked about this being the third method t...
- Wed Jan 22, 2020 5:33 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6D.5
- Replies: 2
- Views: 111
Re: 6D.5
[quote="Connor Ho 1B"] For part (a), here's how I went through it: [b]2. From the table in the chapter, we know that the K b of NH 3 is 1.8 x 10 -5 . We would plug this number into the K equation for this chemical reaction (Note: this is less than 10 -3 , so you can later estimate x by rem...
- Wed Jan 15, 2020 5:19 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: HW 5I.3
- Replies: 2
- Views: 262
HW 5I.3
"In a gas-phase equilibrium mixture of H2, I2, and HI at 500. K, [HI] is 2.21 x 10^-3 mol/L and [I2] is 1.46 x 10^-3 mol/L. Given the value of the equilibrium constant in Table 5G.2, calculate the equilibrium molar concentration of H2." How do you solve this? I looked at the table and I th...
- Wed Jan 15, 2020 4:56 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sig Figs on HW 5H.1c
- Replies: 4
- Views: 181
Re: Sig Figs on HW 5H.1c
Jamie Lee 1F wrote:41 is two sig figs, so your answer should also be two sig figs, so 1.7 x 10^3!
If that is so, can you explain why the answer for 5I.1 is 1.4 when the answer you get is 1.370, and every other given number has more sigfigs than 1.4?
- Wed Jan 15, 2020 4:43 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5.H.3
- Replies: 3
- Views: 148
Re: 5.H.3
I am also confused, can someone explain which two equations would form this one?
- Wed Jan 15, 2020 4:32 pm
- Forum: Ideal Gases
- Topic: What is the Importance of homogeneous vs heterogeneous equilibria [ENDORSED]
- Replies: 12
- Views: 504
Re: What is the Importance of homogeneous vs heterogeneous equilibria [ENDORSED]
It's also important to note that for a homogeneous gas equilibrium, we can calculate Kp, but we cannot calculate Kp for a heterogeneous equilibrium that involves both gas and aqueous species. Thank you for pointing that out! We would have to convert everything into concentrations, not partial press...
- Wed Jan 15, 2020 4:31 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sig Figs on HW 5H.1c
- Replies: 4
- Views: 181
Sig Figs on HW 5H.1c
If you have 41^2, that becomes 1681. Why is the answer written as 1.7 x 10^3?
- Fri Jan 10, 2020 12:19 am
- Forum: Ideal Gases
- Topic: What is the Importance of homogeneous vs heterogeneous equilibria [ENDORSED]
- Replies: 12
- Views: 504
Re: What is the Importance of homogeneous vs heterogeneous equilibria [ENDORSED]
It's also important to note that for a homogeneous gas equilibrium, we can calculate Kp, but we cannot calculate Kp for a heterogeneous equilibrium that involves both gas and aqueous species. Thank you for pointing that out! We would have to convert everything into concentrations, not partial press...
- Fri Jan 10, 2020 12:18 am
- Forum: Ideal Gases
- Topic: 5G.11
- Replies: 6
- Views: 185
Re: 5G.11
I think if you are not given any values, you would simply write out the Q expression with the molecular formula placeholders in the square brackets. Q and K would be the same if no values are given, considering Q is calculated during a specific point in the reaction when there must be actual values ...
- Fri Jan 10, 2020 12:11 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K of Ionic Compounds in Solution
- Replies: 4
- Views: 183
Re: K of Ionic Compounds in Solution
Basically, it's telling you to ignore spectator ions like Li+, Na+, K+, Rb+, Sr2+, Ba2+, Cl-, Br-, I-, NO3-, ClO4-, SO4(2-), etc. because these ions occur in the same form on the left and right side of the chemical equation. So when you're writing your equilibrium constant expression they'd cancel ...
- Fri Jan 10, 2020 12:07 am
- Forum: Ideal Gases
- Topic: Calculating K when there is multiple phases
- Replies: 4
- Views: 194
Re: Calculating K when there is multiple phases
Thank you for clarifying why aqueous solutions cannot have partial pressure; I was under the impression that you could convert either to partial pressure or concentration for each of them.
- Wed Jan 08, 2020 11:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K of Ionic Compounds in Solution
- Replies: 4
- Views: 183
K of Ionic Compounds in Solution
"A final point is that, when a reaction involves fully dissociated ionic compounds in solution, the equilibrium constant should be written for the net ionic equation by using the activity for each type of ion. The concentrations of the spectator ions cancel and so do not appear in the equilibri...
- Sat Dec 07, 2019 12:39 pm
- Forum: Student Social/Study Group
- Topic: Final Jitters
- Replies: 457
- Views: 336741
Re: Final Jitters
Drake Choi_1I wrote:Does anyone know when Test 2 will be passed back?
Your TA should have passed it back by now in discussion.
- Sat Dec 07, 2019 12:38 pm
- Forum: Student Social/Study Group
- Topic: Final Jitters
- Replies: 457
- Views: 336741
Re: Final Jitters
Get enough sleep the night before and don't cram the day of. Pack all your materials the night before so you don't scramble for it. Eat a good breakfast and give yourself some time to relax before it starts.
- Sat Dec 07, 2019 12:29 pm
- Forum: Significant Figures
- Topic: Sig Figs on Midterm Q4 Part 2
- Replies: 3
- Views: 394
Sig Figs on Midterm Q4 Part 2
Why does the answer (0.08567) have only 4 sig figs when the information given to you is 102.557 (nm) and 100 kJ? Does the use of Avogadro's number (6.022 x 1023) affect this?
- Sat Dec 07, 2019 12:21 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Midterm Question 4 Part 2, photon absorption
- Replies: 1
- Views: 311
Midterm Question 4 Part 2, photon absorption
"Light with a wavelength of 102.557 nm excites a hydrogen-atom gas sample . . . If 100 kJ of energy was absorbed by the gas sample, how many photons in total caused electronic excitations? How many moles of hydrogen were excited assuming one photon interacted with one unique hydrogen atom?"...
- Fri Dec 06, 2019 11:21 am
- Forum: Bond Lengths & Energies
- Topic: Hydrogen Bonding
- Replies: 13
- Views: 1037
Re: Hydrogen Bonding
It should also be noted that if O happens to have 2 lone pairs, H-bonding can happen at each of those sites, meaning that O can H-bond twice.
- Sun Dec 01, 2019 12:26 pm
- Forum: Amphoteric Compounds
- Topic: Amphiprotic
- Replies: 11
- Views: 560
Re: Amphiprotic
Would water be considered both amphiprotic and amphoteric?
- Sun Dec 01, 2019 12:21 pm
- Forum: Lewis Acids & Bases
- Topic: Lewis vs. Bronsted
- Replies: 3
- Views: 118
Lewis vs. Bronsted
Which one do we use in lecture most often, and is it necessary to specify on exams?
- Sun Dec 01, 2019 12:17 pm
- Forum: Amphoteric Compounds
- Topic: 6A. 11
- Replies: 3
- Views: 253
Re: 6A. 11
For each (a) and (b), you would get two equations, one where the compound acts as a base and one where it acts as an acid.
- Mon Nov 25, 2019 11:39 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Multiple Bonding Sites
- Replies: 1
- Views: 76
Multiple Bonding Sites
If given the molecular formula of a ligand would you be able to figure out how many possible bonding places of the ligand there are without having to draw the Lewis structure?
9C.3d
What is the purpose of having the "diaqua" in parentheses in sodiumbisoxalato(diaqua)ferrate(III)? What does that tell you?
- Sun Nov 24, 2019 9:17 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Numbers
- Replies: 4
- Views: 307
Coordination Numbers
If you were just given a transition metal, would you be able to estimate what coordination numbers it would have? I am under the impression that coordination numbers tell you how many bonds that TM can form.
- Sun Nov 24, 2019 9:12 pm
- Forum: Naming
- Topic: Order in Naming
- Replies: 12
- Views: 677
Re: Order in Naming
Leslie Almaraz wrote:When given the name of the compound, does it matter the order in which you formulate the atomic symbols?
Could you clarify what you mean by "atomic symbol"?
- Sun Nov 24, 2019 9:11 pm
- Forum: Naming
- Topic: Week 9 and Week 10 HW?
- Replies: 21
- Views: 968
Re: Week 9 and Week 10 HW?
Can anyone clarify about the homework under Molecular Shape and Structure in the syllabus that is 2F? Has Lavelle ever gone over the topics in 2F, and should we do homework problems from that set?
- Sun Nov 24, 2019 8:49 pm
- Forum: Hybridization
- Topic: Basics
- Replies: 2
- Views: 111
Re: Basics
Hybridization is when atomic orbitals are mixed into hybrid orbitals so that chemical bonding is easier. Basically, electrons can move into new hybrid orbitals and these orbitals are used to create bonds with other hybrid orbitals in different atoms in order to for a molecule. Can you explain what ...
- Mon Nov 18, 2019 10:57 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: AXE formula
- Replies: 9
- Views: 519
Re: AXE formula
If there is no central atom, there would simply be no A in the formula. For example, in I3-, the formula is X2E3 because there is no central atom. (This is problem 2E13A)
- Mon Nov 18, 2019 10:54 pm
- Forum: Lewis Structures
- Topic: Bent or Angular?
- Replies: 18
- Views: 1091
Bent or Angular?
Is bent or angular the best term to use to describe a trigonal planar/tetrahedral with one lone pair? VSEPR charts online use the term "bent," but the textbook calls them "angular".
- Mon Nov 18, 2019 10:51 pm
- Forum: Lewis Structures
- Topic: Organic Compounds
- Replies: 2
- Views: 182
Re: Organic Compounds
I can see where you would be confused, because I am as well. All I know is that on the tests, when there are complex compounds, the test question seems to indicate where the central atoms are and what they are bonded to, and then you could probably go from there.
- Mon Nov 18, 2019 10:48 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: ion dipole interactions
- Replies: 3
- Views: 281
Re: ion dipole interactions
I think so, because mixing ions into water (which is polar) would cause the more positive dipole on the H of water to attract/be attracted to the chlorine ion. I think the term polar would apply to ions in this case; polar seems to just be if there is a net charge that is not zero.
- Mon Nov 18, 2019 10:43 pm
- Forum: Lewis Structures
- Topic: Octet Rule
- Replies: 7
- Views: 623
Octet Rule
Can elements that break the octet rule only do so until their formal charge becomes zero, or is the formal charge not a major factor for the octet rule?
- Mon Nov 18, 2019 10:39 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma Bonds
- Replies: 2
- Views: 150
Sigma Bonds
Is it possible for a central atom to have multiple sigma bonds, each connected to a different atom? Or does the one sigma bond rule hold true for the entire atom?
- Sat Nov 09, 2019 6:15 pm
- Forum: Dipole Moments
- Topic: 3F.19
- Replies: 1
- Views: 146
3F.19
Can someone explain parts B and C? For B, I am confused about why the hydrogen bonding in water is stronger than the attractive forces in diethyl ether. I thought diethyl ether would also have hydrogen bonding. For C, why does a lower surface area due to the compactness of dimethylpropane cause it t...
- Sat Nov 09, 2019 5:59 pm
- Forum: Dipole Moments
- Topic: 3F.5
- Replies: 2
- Views: 182
3F.5
Can someone explain why CHI3 has a higher melting point that CHF3? If fluorine is more electronegative than chlorine, wouldn't it have a stronger hold on the electrons and cause there to be a higher melting point instead?
- Sat Nov 09, 2019 5:44 pm
- Forum: Dipole Moments
- Topic: Summary of all the Different Possible Forces?
- Replies: 1
- Views: 77
Summary of all the Different Possible Forces?
Can someone give a quick and easy-to-remember summary for all the forces? (Ion-Dipole, Dipole-Dipole, London, and Hydrogen Bonding) Can you also provide examples where multiple can exist in the same molecule?
- Sat Nov 09, 2019 5:39 pm
- Forum: Dipole Moments
- Topic: How do i know if a molecule has a dipole moment?
- Replies: 7
- Views: 375
Re: How do i know if a molecule has a dipole moment?
To summarize, all molecules have dipole moments unless they are between the same element and/or symmetrical?
- Wed Nov 06, 2019 12:31 pm
- Forum: Empirical & Molecular Formulas
- Topic: Number 1 in Dino Nuggets
- Replies: 3
- Views: 293
Re: Number 1 in Dino Nuggets
Your explanation was super helpful, but can you explain why you don't know where the O is coming from? Why can't you just add the mol of Oxygen from CO2 and H2O?
- Tue Oct 29, 2019 9:09 pm
- Forum: Ionic & Covalent Bonds
- Topic: Midterm
- Replies: 10
- Views: 484
Re: Midterm
I think that we need a blue book, since it is an official midterm, as well as a scientific calculator for basic calculations. Other than that, some extra pens would be good to have on hand too. And I haven't heard anything about the midterm locations yet, so he will probably be sending out an email...
- Tue Oct 29, 2019 9:03 pm
- Forum: Ionic & Covalent Bonds
- Topic: HW 2A19
- Replies: 1
- Views: 105
HW 2A19
For part e, why are there two unpaired electrons for Ni2+?
- Tue Oct 29, 2019 8:10 pm
- Forum: Ionic & Covalent Bonds
- Topic: Homework 2A15
- Replies: 3
- Views: 204
Re: Homework 2A15
For Gallium to give away 3 electrons requires lower energy compared to accepting 5 electrons.
- Tue Oct 29, 2019 8:00 pm
- Forum: Ionic & Covalent Bonds
- Topic: Textbook question 2A.1
- Replies: 2
- Views: 153
Re: Textbook question 2A.1
Going off of what Connie said, the 3d block is already filled so you don't have to include those electrons in when you count; a good rule of thumb for me is to see what column (group) the element is in and use that number. Sb is in the 5th group from the left if you disregard the d block of metals.
- Tue Oct 29, 2019 7:55 pm
- Forum: Ionic & Covalent Bonds
- Topic: How to count valence electrons with the d block
- Replies: 4
- Views: 339
Re: How to count valence electrons with the d block
The textbook problem 2A.1c states that Mn has 7 valence electrons, but it is very clear about "including d electrons."
- Sun Oct 27, 2019 1:44 pm
- Forum: Lewis Structures
- Topic: Expanded Octet
- Replies: 6
- Views: 196
Re: Expanded Octet
If that is the case, why even have the Octet rule? I understand that it is an easy rule of thumb for many elements, but if it does not really apply after the d-orbital comes into play, is it really helpful?
- Sun Oct 27, 2019 1:43 pm
- Forum: Ionic & Covalent Bonds
- Topic: "Delocalized" Electrons
- Replies: 5
- Views: 212
Re: "Delocalized" Electrons
I am also confused. I thought covalent bonds were ones in which the electron was already free to move around, so I am not understanding how an electron can be free to move around the entire molecule instead. What allows it to do so?
- Sun Oct 27, 2019 1:39 pm
- Forum: Ionic & Covalent Bonds
- Topic: Writing Electron Configurations for an Ion
- Replies: 6
- Views: 278
Re: Writing Electron Configurations for an Ion
I'm not too confident on this topic either, but I'm pretty sure you remove or add an electron to the highest energy level depending on whether you want a cation or anion. For example, to change Zinc from its ground-state to Zn+, you take the ground state configuration [Ar]3d^104s^2 and remove an el...
- Sun Oct 27, 2019 1:37 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3040312
Re: Post All Chemistry Jokes Here
Do you know any good jokes about Sodium Hypobromite?
NaBrO
NaBrO
- Sun Oct 27, 2019 1:34 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3040312
Re: Post All Chemistry Jokes Here
Why are noble gases good at singing?
Because their resonance is the most stable!
Because their resonance is the most stable!
- Sun Oct 20, 2019 11:12 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3040312
Re: Post All Chemistry Jokes Here
Have you seen the new James Bond movie?
The name's Bond. Covalent Bond.
The name's Bond. Covalent Bond.
- Sun Oct 20, 2019 11:11 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3040312
Re: Post All Chemistry Jokes Here
Why is Helium the best audience for a comedy show?
Because it always says He He He.
Because it always says He He He.
- Sun Oct 20, 2019 11:08 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Purpose of the Equation
- Replies: 9
- Views: 320
Re: Purpose of the Equation
The more you know about the velocity, the less you know about the speed, and vice versa. The reason for this according to Dr. Lavelle is that the process of observing either one of those influences the other. If you set up more sensors to get accurate velocities, you will move the electron off cours...
- Sun Oct 20, 2019 12:58 pm
- Forum: Photoelectric Effect
- Topic: Work Function
- Replies: 9
- Views: 597
Re: Work Function
Dr. Lavelle uses those terms practically interchangeably when discussing the photoelectric effect.
- Thu Oct 17, 2019 10:31 pm
- Forum: Properties of Electrons
- Topic: 1B.3
- Replies: 3
- Views: 168
Re: 1B.3
I think Dr. Lavelle went over this in class while explaining the photoelectric effect. He did not go over black body radiation much, and atomic spectra relates to electrons, not electromagnetic radiation, so that narrows it down to either electron diffraction or the photoelectric effect. I chose to ...
- Sat Oct 12, 2019 10:29 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3040312
Re: Post All Chemistry Jokes Here
My Chem teacher argued that Iron Man was a woman.
Fe-male
Fe-male
- Sat Oct 12, 2019 10:28 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Tutoring? [ENDORSED]
- Replies: 121
- Views: 241945
Re: Tutoring? [ENDORSED]
I reached out to Alpha Chi Sigma and was told that tutoring would start Week 3, so make sure to contact them once Monday starts!
- Sat Oct 12, 2019 10:24 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3040312
Re: Post All Chemistry Jokes Here
What element best describes me?
The element of indecision: Imnotsurium
The element of indecision: Imnotsurium
- Sat Oct 12, 2019 10:22 pm
- Forum: Student Social/Study Group
- Topic: Final Jitters
- Replies: 457
- Views: 336741
Re: Final Jitters
I took Quiz 1 after running into the room 3 minutes late and I was panicking, but I calmed down and thought out my answers. I would say that the best thing to do is review everything that you need on the syllabus: pen, non-graphing calculator, etc. If something will be given, don't try to remember e...
- Sat Oct 12, 2019 10:16 pm
- Forum: Properties of Light
- Topic: Light intensity and Kinetic Energy
- Replies: 7
- Views: 380
Re: Light intensity and Kinetic Energy
I think that Lily is right in saying that there is no correlation between light intensity and the kinetic energy in the equation E=hv.
- Sat Oct 12, 2019 9:56 pm
- Forum: Properties of Light
- Topic: 1A.3
- Replies: 4
- Views: 208
Re: 1A.3
C would be the correct answer. Think of the "change in the electrical field" as slope-- how steep a wave goes. As frequency decreases, the waves stretch out farther and the slope would be less steep because they are now farther apart.
- Wed Oct 02, 2019 10:11 pm
- Forum: Properties of Light
- Topic: Electric Field and Magnetic Field
- Replies: 3
- Views: 184
Re: Electric Field and Magnetic Field
What effect does the magnetic field have on the electrons, then?
- Sun Sep 29, 2019 10:15 pm
- Forum: Empirical & Molecular Formulas
- Topic: Empirical Formulas Rounding and Multiplying
- Replies: 11
- Views: 644
Re: Empirical Formulas Rounding and Multiplying
I personally feel like the general rule of thumb for round should include only integers ending in 0.5 or 0.33. Anything else, can either be rounded up or down. For example: If your result is a number that is 2.55, obviously round that to just 2.5. I understand that you would round 2.55 to 2.5, but ...
- Sat Sep 28, 2019 5:23 pm
- Forum: Empirical & Molecular Formulas
- Topic: Empirical Formulas Rounding and Multiplying
- Replies: 11
- Views: 644
Re: Empirical Formulas Rounding and Multiplying
What should the threshold be for decimals when solving for empirical formulas? I think that if the results are 0.1 away from the nearest whole number, then you round to that whole number. Otherwise, I think you multiply to the nearest whole number. However, I see in some example problems, like one ...