Search found 109 matches
- Sat Mar 14, 2020 7:35 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: HW 7.17
- Replies: 1
- Views: 126
Re: HW 7.17
A catalyst, unlike an intermediate, can be included in the rate law, so if a catalyst is in the rate determining step, it can affect the overall rate law, I believe.
- Sat Mar 14, 2020 7:33 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Reaction Profile
- Replies: 2
- Views: 282
Re: Reaction Profile
I don't think we have enough information to determine how large of a dip there should be, but as long as we show that the energy decreases and then increases again, we should be good!
- Sat Mar 14, 2020 7:32 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: 7B 3(c)
- Replies: 2
- Views: 279
Re: 7B 3(c)
I am also slightly confused by this question, but what I think is happening is that we are given an initial concentration of A as 0.153 M, and then we use the information that after 115s, there is 0.024 mol B. Since B is a product, we had to have used some of the A to form B, so we have to subtract ...
- Sat Mar 14, 2020 7:19 pm
- Forum: General Rate Laws
- Topic: 7A.11( part b)
- Replies: 1
- Views: 185
Re: 7A.11( part b)
Hi! For this question, the overall reaction is second order, but each individual reactant is first order. Therefore, doubling the concentration of H2 will only double the rate or reaction. You are right that if H2 were by itself second order, it would quadruple the rate; however, the order of reacti...
- Sat Mar 14, 2020 7:16 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kw and other constants
- Replies: 9
- Views: 679
Re: Kw and other constants
The w refers to water, so the equilibrium constant for water is 1.0x10-14. Ka and Kb multiply to Kw because water is neutral. The case of the w (upper case or lower) does not matter, I don't think, it is merely there to indicate this specific constant for water.
- Sat Mar 14, 2020 7:14 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: endgame 5
- Replies: 1
- Views: 233
Re: endgame 5
For number 5, it is specially asking us to find the Ka value of HF, meaning we must treat HF as an acid. Therefore, HF will have to be the reactant and the half reaction involving HF must be flipped despite its larger standard cell potential. Usually, we flip the lower cell potential to result in a ...
- Sat Mar 14, 2020 7:11 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Final Review
- Replies: 2
- Views: 343
Re: Final Review
I'm not sure if this is the what you are getting at, but when there are intermediates in the rate-determining step (i.e the slow step), you need to replace the intermediates with the correct reactants to match the determined rate law. In order to do this, you need to solve for the intermediates usin...
- Wed Mar 11, 2020 4:15 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: salt bridge
- Replies: 11
- Views: 607
Re: salt bridge
In a Galvanic cell, electrons flow form the anode to the cathode which results in solutions holding charges. The anode will become positive as it loses electrons, and the cathode solution will becomes more negative as it gains electrons. The salt bridge is put in place to neutralize the solutions. T...
- Sun Mar 08, 2020 11:05 pm
- Forum: Van't Hoff Equation
- Topic: What's the purpose of Van't Hoff?
- Replies: 5
- Views: 496
Re: What's the purpose of Van't Hoff?
The Van't Hoff equation allows you to calculate the equilibrium constant or temperature of an equation using another equation.
It is derived using the equations Detla G=deltaH-TdeltaS and deltaG=-RTlnK. Putting these together gives you the van't Hoff equation!
It is derived using the equations Detla G=deltaH-TdeltaS and deltaG=-RTlnK. Putting these together gives you the van't Hoff equation!
- Sun Mar 08, 2020 10:55 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Speed of a reaction
- Replies: 2
- Views: 196
Re: Speed of a reaction
Generally, if a reaction occurs in multiple steps, the slow reaction is the rate-determining step. So, if the rate law is given, look at the multistep reaction and find which reaction corresponds to the rate law, and this will be the slow reaction and the remaining reactions fast. I also think that ...
- Sun Mar 08, 2020 10:52 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Work max
- Replies: 4
- Views: 454
Re: Work max
Delta G refers to the energy available to do work, so the maximum work that can be done is equal to energy available to do that work!
I don't believe there are any exceptions to this rule!
I don't believe there are any exceptions to this rule!
- Sun Mar 08, 2020 10:50 pm
- Forum: First Order Reactions
- Topic: Derivation of Integrated Rate Laws
- Replies: 1
- Views: 155
Re: Derivation of Integrated Rate Laws
The Integrated rate laws help you determine if the reaction is zero, first, or second order reactions when graphed, as the integrated laws represent linear functions. I do not believe you need to know how to derive them as the equations are listed on the constants sheet, but it is good to have a bas...
- Sun Mar 08, 2020 10:47 pm
- Forum: Ideal Gases
- Topic: When do we change PV=NRT into deltas?
- Replies: 4
- Views: 444
Re: When do we change PV=NRT into deltas?
If you change a variable on one side of the equation to a delta, so either delta P or delta T, you have to change a variable on the other side of the equation, so it would either be delta T or delta n. There cannot be a delta R as this is a constant. You can use the information given in the problem ...
- Sun Mar 01, 2020 4:55 pm
- Forum: Balancing Redox Reactions
- Topic: H+ or H2O
- Replies: 4
- Views: 288
Re: H+ or H2O
In an acidic solution, you would use H2O to balance the oxygen, and you would use H+ to balance the Hydrogen. In a basic solution, you use H2O to balance the O and the H, but when you add water molecules to one side of the reaction to balance Hydrogen, you have to add the same number of hydroxide OH...
- Sun Mar 01, 2020 4:52 pm
- Forum: Administrative Questions and Class Announcements
- Topic: HW 9
- Replies: 5
- Views: 392
Re: HW 9
Test 9 is covering the last page of the thermodynamics syllabus and the electrochemistry syllabus.
This refers to HW problems:
5G: 13, 15, 17, 19, 21
5J: 11,13, 15
5.55, 5.61
And all the HW probs outlined on the electrochemistry syllabus (Focus 6K-6O.1)
This refers to HW problems:
5G: 13, 15, 17, 19, 21
5J: 11,13, 15
5.55, 5.61
And all the HW probs outlined on the electrochemistry syllabus (Focus 6K-6O.1)
- Sun Mar 01, 2020 4:48 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Deriving the Nernst Equation
- Replies: 3
- Views: 331
Re: Deriving the Nernst Equation
Hey! I think you are correct in your thought process. You just have to make sure that is you are using standard conditions for delta G, you use standard conditions for the remaining variables and this yields the standard cell potential. I believe as long as you are consistent, you can use both delta...
- Sun Mar 01, 2020 4:45 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: cell potential
- Replies: 15
- Views: 770
Re: cell potential
When the Cell Potential is positive, this refers to a negative delta G and therefore a spontaneous reaction which proceed over time, not necessarily in a fast manner.
- Sun Mar 01, 2020 4:44 pm
- Forum: Balancing Redox Reactions
- Topic: moles of electrons transferred
- Replies: 4
- Views: 315
Re: moles of electrons transferred
You can look at the change in charge of a species or look for the change in oxidation numbers of a species from reactants to products! This will relate to the number of moles of electrons transferred.
- Sun Feb 23, 2020 7:27 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6L.5 b)
- Replies: 5
- Views: 307
Re: 6L.5 b)
At times, you will have to use an inert conductor such as platinum as en electrode to transfer electrons!
- Sun Feb 23, 2020 7:23 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation Numbers- How to Find
- Replies: 3
- Views: 326
Re: Oxidation Numbers- How to Find
There are certain oxidation numbers attached to certain elements, and these do not differ between reaction so you can use these known values to determine unknown ones, such as the oxidation numbers of transition metals which tend to vary according to the compound that they are present in. For exampl...
- Sun Feb 23, 2020 7:19 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic Cell Notation
- Replies: 3
- Views: 304
Re: Galvanic Cell Notation
In certain cases, you would add a solid agent. Dr. Lavelle mention platinum in class!
- Wed Feb 12, 2020 3:42 pm
- Forum: Phase Changes & Related Calculations
- Topic: internal energy
- Replies: 2
- Views: 276
Re: internal energy
Constant temperature (isothermal) indicates that delta U is 0. Constant pressure allows you to set q equal to delta H, and the work is -PdeltaV.
- Sun Feb 09, 2020 10:29 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: positive-negative entropy
- Replies: 1
- Views: 130
Re: positive-negative entropy
When a system can take more possible states, the entropy is greater. For example, a gas which has more space to take different states, the entropy is greater than say a solid, whose particles are more confined to fewer possible states.
- Sun Feb 09, 2020 10:25 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Specific Heat Capacity
- Replies: 5
- Views: 156
Re: Specific Heat Capacity
You use specific heat capacity when the mass is given in grams. You can use q=mCdeltaT, where C is specific heat capacity. You can use q=nCdeltaT when the C is molar heat capacity.
- Sun Feb 09, 2020 10:23 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: q rev
- Replies: 4
- Views: 268
Re: q rev
A system undergoes reversible expansion when the change is made with infinitesimal changes to pressure. In a irreversible expansion, the change cannot be undone, and the reaction proceeds with a constant external pressure.
- Sun Feb 09, 2020 10:21 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: m and n in heat capacity
- Replies: 4
- Views: 172
Re: m and n in heat capacity
When you refer to the mass in grams, you will use specific heat capacity, which is J per gram degree celsius, so we multiplying you are left with J. When you use moles, you will use the molar heat capacity in the equation, which is in J per mol degree celsius, so once again you are left with J.
- Sun Feb 09, 2020 10:19 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Ideal Gasses
- Replies: 2
- Views: 165
Re: Ideal Gasses
Unless otherwise, I believe we assume the gases we are dealing with behave in an ideal manner, following PV=nRT.
- Sun Feb 02, 2020 10:30 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: State Function
- Replies: 4
- Views: 274
Re: State Function
Internal energy does not depend on the path a reactions takes. It describes an equilibrium state of a thermodynamic system.
- Sun Feb 02, 2020 10:26 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Work and Heat
- Replies: 2
- Views: 56
Re: Work and Heat
Work and heat are dependent functions, and they only appear when a change occurs to a system, therefore they are not state functions.
- Sun Feb 02, 2020 10:16 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Steam burns
- Replies: 8
- Views: 258
Re: Steam burns
If you look at a phase change graph, you will see that the change between liquid and gas is represented by a straight line in which heat is increasing but the substance has not yet changed phases. Therefore, steam holds a greater temperature.
- Sun Feb 02, 2020 10:11 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Test 1
- Replies: 3
- Views: 205
Re: Test 1
I got mine back in my discussion in week 4! If you did not get yours back, I'm sure you will get it back this week!
- Sun Feb 02, 2020 10:10 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: State Property
- Replies: 5
- Views: 156
Re: State Property
Enthalpy is a state property, meaning that it is a value that does not depend on the path taken to achieve a certain value, only that value in a certain instant. For example, think of a mountain and an object. An object will be a certain height up the mountain regardless of how that height was achie...
- Sun Jan 26, 2020 11:04 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: State Functions
- Replies: 4
- Views: 248
Re: State Functions
Heat and work are not state functions, but enthalpy is a state function!
- Sun Jan 26, 2020 11:03 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: delta s
- Replies: 5
- Views: 215
Re: delta s
Delta s is entropy!
Delta H is enthalpy!
Delta H is enthalpy!
- Sun Jan 26, 2020 2:36 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: clarification from lecture - "state function"
- Replies: 2
- Views: 62
Re: clarification from lecture - "state function"
A state function describes a system at a given instant but is not dependent on how that current state was achieved. A state function depends only on the final and initial state but not the path that was taken. I believe in class Dr. Lavelle one over an example involving a mountain to discuss this id...
- Sun Jan 26, 2020 2:29 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Lewis Structures Method 2
- Replies: 6
- Views: 147
Re: Lewis Structures Method 2
It is not necessary, but it will help you to visualize how many bonds are broken on the reactant side and how many are formed on the product side.
- Sun Jan 26, 2020 2:25 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase Changes endo/exo
- Replies: 3
- Views: 121
Re: Phase Changes endo/exo
Yes, some phase changes are exothermic. If you go from a system of higher energy to a system of lower energy, it will be an exothermic reactions. For example, going from a gas to a liquid in vaporization (or commonly called condensation) reaction, it is exothermic because the gas has a higher energy...
- Sun Jan 19, 2020 11:30 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Clarification on these statements
- Replies: 2
- Views: 154
Re: Clarification on these statements
Both of those statements mean the same. If to maintain equilibrium, the reaction will proceeds to the right, that means more products will be formed which can also be stated with equilibrium lies to the right.
- Sun Jan 19, 2020 11:28 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier's principle
- Replies: 7
- Views: 380
Re: Le Chatelier's principle
Le Chatelier's principle explains what a reaction will do to maintain equilibrium when the conditions are altered. If more reactant is added to the system, the reaction will proceed towards the products to maintain equilibrium. Keep in mind that the equilibrium constant is a constant ratio between p...
- Sun Jan 19, 2020 11:24 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Endothermic Reaction.
- Replies: 7
- Views: 231
Re: Endothermic Reaction.
Usually, the delta H value will be given. If this value is positive, it is an endothermic reaction. If this value is negative, it is an exothermic reaction because heat is being given off. Endothermic reactions require energy to proceed, so if a reactant is held tightly together through strong inter...
- Sun Jan 19, 2020 11:22 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: identifying acids & bases
- Replies: 5
- Views: 297
Re: identifying acids & bases
The acid is the molecule that donates and H+ tp form H3O+, whereas a base is a substance that accepts an H+ and forms OH- as products. The conjugate acid/base form as a result of the transfer of H+. For example, HCl+H2O-->H3O+ + Cl-. This is an example of an acid donating an H+. HCl is the acid, H2O...
- Sun Jan 19, 2020 11:18 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Applying Kw
- Replies: 2
- Views: 116
Re: Applying Kw
Ba2+ is the cation of a strong base, so when it dissociates it will not affect the pH of the solution. Kw refers to the equilibrium constant for water, and shows how water has a neutral pH of 7. So the OH will increase the pH which changes the Kb and therefore allows us to calculate the Ka using Kw=...
- Fri Jan 17, 2020 1:05 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Homework question 5J.5
- Replies: 3
- Views: 180
Homework question 5J.5
For question 5J.5, many reactions are given and we are asked to predict whether the reactants or products would be favored with an increase in total pressure. One of the reactions is 2HD(g)+H2(g)⇌D2(g). The answer says no change, but wouldn't the reaction favor the products because there are less mo...
- Sun Jan 12, 2020 6:25 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Reaction Quotient Q
- Replies: 6
- Views: 145
Re: Reaction Quotient Q
Q is calculated when an equation is not at equilibrium, whereas K uses equilibrium values!
- Sun Jan 12, 2020 6:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: memorization
- Replies: 12
- Views: 562
Re: memorization
I do not believe we will have to memorize any K values. Dr. Lavelle will provide us any values we need to know.
- Sun Jan 12, 2020 6:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Example 5I.3 (page 556 on pdf)
- Replies: 3
- Views: 79
Re: Example 5I.3 (page 556 on pdf)
Removing these x terms makes the solving easier, if you do not want to use the Quadratic equation. If the change in concentration/pressure (x) is less than 5% of the initial value, you can remove the x terms as the values will be so small that they do not affect the final answer. You have to make su...
- Sun Jan 12, 2020 6:21 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Application of La Chatelier's
- Replies: 3
- Views: 127
Re: Application of La Chatelier's
You apply Le Chatelier's principle in problems that ask you which way a reaction will proceed to maintain equilibrium. If a reactant is added, the reaction will proceed toward the products to maintain equilibrium, and vice versa. Remember that K is a constant ration of products over reactants.
- Sun Jan 12, 2020 6:19 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Q>K
- Replies: 9
- Views: 250
Re: Q>K
Q is calculated using non-equilibrium values. If Q>K, that means that the reaction will proceed to the left, or toward the reactants, to reach equilibrium. The products will be used up to produce more reactants, which in turn will raise the values for the reactants and lower the Q value until Q=K an...
- Sun Jan 12, 2020 6:16 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K units
- Replies: 3
- Views: 88
Re: K units
There is no unit for K, it is a unites value. If you were to include units for every value used to calculate K, the units would all cancel, which leaves K without any units!
- Sun Jan 12, 2020 6:15 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K and Q
- Replies: 10
- Views: 256
Re: K and Q
K and Q are calculated in the same way, except that K uses the values from equilibrium and Q uses initial conditions/conditions not at equilibrium. You can use the value of Q to determine which way the the reaction will proceed to reach equilibrium!
- Sun Jan 12, 2020 6:13 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Calculating K
- Replies: 9
- Views: 201
Re: Calculating K
K does not include pure liquids or solids, merely aqueous solutions and gases!
- Sat Dec 07, 2019 6:20 pm
- Forum: Biological Examples
- Topic: Vitamin B12
- Replies: 1
- Views: 155
Re: Vitamin B12
Hey! I am not sure what the ligands are, but I know that the transition metal of Vitamin B12 is Cobalt!
- Sat Dec 07, 2019 6:15 pm
- Forum: Conjugate Acids & Bases
- Topic: chemical equations of acids and bases
- Replies: 2
- Views: 212
Re: chemical equations of acids and bases
Hey! You use a reverse arrow when the reaction does not involve a strong acid or a strong base! When a strong acid or base is present, you use a single sided arrow because the acid/base dissociates basically completely.
- Sat Dec 07, 2019 6:14 pm
- Forum: Naming
- Topic: Naming coordination compounds
- Replies: 2
- Views: 179
Re: Naming coordination compounds
I do not believe we will be getting the chart! He said we should know everything on the chart though!
- Sat Dec 07, 2019 6:13 pm
- Forum: Naming
- Topic: Oxalate Compound
- Replies: 1
- Views: 106
Re: Oxalate Compound
I believe the name would be sodium trisoxalatocobaltate(III).
Since oxalate is bidentate, you use -tris instead of -tri, and since the overall charge of the coordination complex is negative, you add -ate to the name of the transition metal.
Since oxalate is bidentate, you use -tris instead of -tri, and since the overall charge of the coordination complex is negative, you add -ate to the name of the transition metal.
- Sat Dec 07, 2019 6:10 pm
- Forum: Student Social/Study Group
- Topic: amphoteric vs. amphiprotic
- Replies: 4
- Views: 426
Re: amphoteric vs. amphiprotic
Amphoteric means that a certain molecule can act as either an acid or a base, whereas amphiprotic means that a proton can either be accepted or donated. Amphiprotic implies amphoteric, but amphoteric does not imply amphiprotic.
- Sat Dec 07, 2019 5:09 pm
- Forum: Conjugate Acids & Bases
- Topic: Reaction arrows
- Replies: 3
- Views: 268
Re: Reaction arrows
Hey! You use a reverse arrow when the reaction does not involve a strong acid or a strong base! When a strong acid or base is present, you use a single sided arrow because the acid/base dissociates basically completely.
- Sat Dec 07, 2019 4:52 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Polydentate
- Replies: 1
- Views: 110
Polydentate
Is Carbonate considered bidentate like oxalate? If it is, is it due to that negatively charged oxygen atoms or is there another reason?
- Sun Dec 01, 2019 11:23 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Trichloroacetic acid
- Replies: 2
- Views: 97
Re: Trichloroacetic acid
Trichloroacetic acid is stronger than acetic acid because the chlorine atoms have higher electronegativity!
- Sun Dec 01, 2019 11:22 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: pka v. ka
- Replies: 4
- Views: 303
Re: pka v. ka
The difference between pKa and Ka is that the pKa is the negative logarithm of Ka. The lower the Ka value, the greater the pKa value, and therefore the stronger the acid.
- Sun Dec 01, 2019 11:18 pm
- Forum: Lewis Acids & Bases
- Topic: Long bonds vs Short bonds?
- Replies: 9
- Views: 872
Re: Long bonds vs Short bonds?
Long bonds are weaker than short bonds because the nuclei are farther apart so there exists less attractive pull. It is easier to break apart a bond when the atoms are farther apart.
- Sun Dec 01, 2019 11:13 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Determing Coordination Number
- Replies: 5
- Views: 224
Re: Determing Coordination Number
I believe that the coordination number refers to the number of bonds within a complex. The example in class was [Fe(CN)6]4- has a coordination number of 6, as there are 6 bonds.
- Sun Dec 01, 2019 11:08 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Conjugate Seesaw
- Replies: 1
- Views: 63
Re: Conjugate Seesaw
I believe the concept of conjugate seesaw refers to how if you have a really strong acid, it would make a weak conjugate base, and if you had a strong base, it would make a weak conjugate acid.
- Sun Dec 01, 2019 11:06 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Class wed 11/27
- Replies: 7
- Views: 498
Re: Class wed 11/27
Dr. Lavelle went over pH and pOH in greater detail, and how to derive the pH scale! If you read the section on acid and base naturalization and the relationship between pH, pOH, and pKa, you should be good!
- Sun Nov 24, 2019 2:40 pm
- Forum: Naming
- Topic: Homework problems Week 9
- Replies: 4
- Views: 236
Re: Homework problems Week 9
Hey!
Yes, I believe you can turn in homework form Focus 9C. As long as the problems you are doing relate to what we are learning in class and are not from sections from completely different topics/outlines, you should be good!
Yes, I believe you can turn in homework form Focus 9C. As long as the problems you are doing relate to what we are learning in class and are not from sections from completely different topics/outlines, you should be good!
- Sun Nov 24, 2019 2:38 pm
- Forum: Naming
- Topic: Chemistry Community
- Replies: 4
- Views: 267
Re: Chemistry Community
Hi! If you are struggling with finding ways to interact on Chemistry Community, it may be beneficial to log on every time you are doing homework or reading the textbook or going over lecture notes, and anytime you question something, post it! It may be easier for you to post a question a day, or try...
- Sun Nov 24, 2019 2:26 pm
- Forum: Dipole Moments
- Topic: Hydrogen bonding
- Replies: 5
- Views: 436
Re: Hydrogen bonding
Do they F, O, and N atoms on a separate molecule have to be bonded directly to a H atom for Hydrogen bonding to be able to occur? For example, in benzoic acid C6H5COOH, there is an O doubled bonded to a C, so the O is not directly bonded to an H. Can this particular O still participate in Hydrogen b...
- Sun Nov 24, 2019 2:19 pm
- Forum: Hybridization
- Topic: Lone pairs
- Replies: 9
- Views: 549
Re: Lone pairs
Hi!
Lone pairs are electron groups and therefore they must affect hybridization, just like they affect shape and bond angles!
Lone pairs are electron groups and therefore they must affect hybridization, just like they affect shape and bond angles!
- Sun Nov 24, 2019 2:16 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: H3O+
- Replies: 12
- Views: 26097
Re: H3O+
Hi!
H3O+ has a molecular geometry of tetrahedral, since there are 4 regions of electron density surrounding the central O atom (3 Hydrogens and 1 lone pair of electrons). The VSEPR shape would be trigonal pyramidal.
H3O+ has a molecular geometry of tetrahedral, since there are 4 regions of electron density surrounding the central O atom (3 Hydrogens and 1 lone pair of electrons). The VSEPR shape would be trigonal pyramidal.
- Sun Nov 17, 2019 9:08 pm
- Forum: Student Social/Study Group
- Topic: Test 2
- Replies: 11
- Views: 506
Re: Test 2
Only the first slide or two (the first 5 minutes of class) will be on the test! The entirety of the lecture will not be on the test.
- Sun Nov 17, 2019 9:07 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Radicals
- Replies: 2
- Views: 145
Re: Radicals
I believe that radical electrons repel in a way similar to a pair of lone pairs, but to a weaker extent because the electron density cloud will be smaller for a single electron. The repulsion is still present and can affect bond angles, but merely to a lesser extent.
- Sun Nov 17, 2019 9:04 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: induced dipole
- Replies: 4
- Views: 233
Re: induced dipole
An induced dipole occurs when a molecule that would not usually possess a dipole forms a dipole due to integration with a molecule containing a dipole. For example, the polarity of HF induces a dipole in N2, a usually non polar molecule. The permanent dipole moment induces a dipole moment, and this ...
- Sun Nov 17, 2019 9:00 pm
- Forum: Student Social/Study Group
- Topic: Test 2
- Replies: 11
- Views: 506
Re: Test 2
Dr. Lavelle also said he will covering sigma and pi bonds in more depth for the first 5 minutes of class tomorrow and that will be on Test 2!
- Sun Nov 17, 2019 8:59 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape of H20
- Replies: 3
- Views: 310
Re: Molecular Shape of H20
H2O has a bent molecular shape rather than a linear shape because the two pairs of lone pair electrons take up more space than a bond, and the electron repulsion pushes away from the atoms to create bond angles less than 180 degrees but rather less than 109.5. The Lone pair electrons will not stay i...
- Sun Nov 17, 2019 8:55 pm
- Forum: Hybridization
- Topic: Pi and sigma bonds
- Replies: 4
- Views: 218
Re: Pi and sigma bonds
Sigma bonds refer to the s-orbital, and occur when two orbitals are overlapping end to end. Sigma bonds have no nodal planes containing the internuclear axis. This is the reason why a single bond contains one sigma bond. A pi bond refers to a p-orbital, and occurs when two orbitals overlap side to s...
- Sun Nov 10, 2019 5:59 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Graph of energy levels
- Replies: 1
- Views: 214
Re: Graph of energy levels
The graph of an electron rising/falling has Energy on the y-axis (and the Energy is negative, building up to E=0). The principal energy levels are drawn parallel to the x-axis (n=1, =2, n=3,..., n= Infinity). To solve for the change in principal energy levels, you need to look for clues in the quest...
- Sun Nov 10, 2019 5:46 pm
- Forum: Octet Exceptions
- Topic: Reasoning for Octet Exception
- Replies: 19
- Views: 1145
Re: Reasoning for Octet Exception
Yes, it is because of the presence of the d-orbital in the elements staring in period 3! This d-orbital can accommodate the extra electrons! If you look at the formal charge for the elements you mentioned (Si, P, S, and Cl) you can see that having more than the octet minimizes the formal charge and ...
- Sun Nov 10, 2019 5:38 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Workshop Sessions
- Replies: 1
- Views: 111
Re: Workshop Sessions
Yes, I believe the workshops and step-ups will continue for the entire quarter!
- Sun Nov 10, 2019 5:35 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 2
- Replies: 4
- Views: 204
Re: Test 2
I am not 100% sure what Test 2 will cover, but as the test is coming up the week of November 19th, I am assuming the test will cover the remainder of Outline 3: Chemical Bonds, and the Outline 4: Molecular Shape and Structure. Dr. Lavelle will let us know for sure sometime soon, I believe!
- Tue Nov 05, 2019 8:52 pm
- Forum: Resonance Structures
- Topic: Resonance structures for (NH2)COCH3 [ENDORSED]
- Replies: 1
- Views: 333
Resonance structures for (NH2)COCH3 [ENDORSED]
In the workshop worksheet from 11/3 with Karen, a question asked, "Experiments indicate that two resonance structures exist for the organic molecule, (NH2)COCH3. Draw them." Why would this molecule form a resonance structure by making Nitrogen radical? Why is it necessary to have a resonan...
- Sun Nov 03, 2019 7:10 pm
- Forum: Lewis Acids & Bases
- Topic: diff b/w lewis acid and base
- Replies: 12
- Views: 651
Re: diff b/w lewis acid and base
A Lewis acid accepts an electron pair, and a Lewis base donates a pair of electrons!
- Sun Nov 03, 2019 7:09 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Question on Atomic Spectrum Post Assessment
- Replies: 3
- Views: 98
Re: Question on Atomic Spectrum Post Assessment
For this question, would you make the energy you calculate from the given frequency negative because it is being emitted?
- Sun Nov 03, 2019 7:04 pm
- Forum: Lewis Structures
- Topic: Lewis Structures and Polarity
- Replies: 1
- Views: 105
Re: Lewis Structures and Polarity
Hi! You can label the dipoles and polarity on a Lewis structure by using an arrow pointing toward the more negative atom, as the electron is being pulled toward that atom, and is creating a negative charge on that atom. I don't believe that polarity directly affects the drawing of Lewis structures a...
- Sun Nov 03, 2019 6:52 pm
- Forum: Resonance Structures
- Topic: Resonance structures
- Replies: 15
- Views: 750
Re: Resonance structures
Resonance structures are when you move electrons within a Lewis structure (such as moving double bonds) to stabilize the structure and delocalize the electrons. The true structure of a Lewis Structure with resonance is a hybrid of all the possible resonance structures.
- Sun Nov 03, 2019 6:50 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: The equation
- Replies: 3
- Views: 246
Re: The equation
Hi!
A lone pair of electrons refers to the electrons that are not involved in bonding when drawing the Lewis structures!
A lone pair of electrons refers to the electrons that are not involved in bonding when drawing the Lewis structures!
- Sun Nov 03, 2019 6:47 pm
- Forum: Properties of Electrons
- Topic: Photoelectric effect
- Replies: 5
- Views: 446
Re: Photoelectric effect
Khan Academy always has really helpful videos, so it is worth checking that out!
- Sun Oct 27, 2019 2:33 pm
- Forum: Ionic & Covalent Bonds
- Topic: He
- Replies: 3
- Views: 173
Re: He
The electron configuration of He is 1s2. When drawing the Lewis structure, you would put these electrons together to show how they are in the same sub shell of the atom. If the valence electrons appear in different sub shells, such as the s and p, you keep the s electrons together and then separate ...
- Sun Oct 27, 2019 2:28 pm
- Forum: Lewis Structures
- Topic: Anion/Cations
- Replies: 2
- Views: 125
Re: Anion/Cations
Traditionally, a Lewis structure of a cation or an anion will be put in brackets and the charge will be placed in the top right corner outside the bracket. For example, sulfate will have a 2- charge written outside the bracket surrounding the Lewis structure to indicate that the structure is not neu...
- Sun Oct 27, 2019 2:25 pm
- Forum: Trends in The Periodic Table
- Topic: Cations
- Replies: 8
- Views: 333
Re: Cations
Cations are smaller because these atoms have a positive charge on their central nucleus, which means that there are more protons than electrons. The positive charge pulls the electrons closer to the nucleus than if there were to be a neutral nucleus. This greater attraction leads to a smaller atomic...
- Sun Oct 27, 2019 2:23 pm
- Forum: Student Social/Study Group
- Topic: Miderm Review
- Replies: 10
- Views: 616
Re: Miderm Review
I am not sure if Dr. Lavelle directly gives study guides, but at the Workshops the UAs give worksheets that go over the concepts. I think these are very helpful, especially to review for the midterm!
- Sun Oct 27, 2019 2:20 pm
- Forum: Resonance Structures
- Topic: Resonance
- Replies: 8
- Views: 172
Re: Resonance
Resonance structures show the possible ways that elements can be bonded. By drawing all possible combinations (such as single, double, triple bonds), we can calculate the formal charge of each configuration to find the most stable arrangement.
- Sun Oct 27, 2019 2:17 pm
- Forum: Ionic & Covalent Bonds
- Topic: Valence Electrons
- Replies: 4
- Views: 221
Re: Valence Electrons
Valence electrons are the electrons in the outermost shell of an atom that are involved in reactions. Transition metals most commonly have 2 valence electrons, such as 4s2 or 5s2. The d electrons are used to write the electron configuration, but may not be used to find valence electrons.
- Sun Oct 20, 2019 8:40 pm
- Forum: Trends in The Periodic Table
- Topic: Study Buddies?
- Replies: 8
- Views: 191
Re: Study Buddies?
That would be awesome! My email is shannonbeall@yahoo.com.
- Sun Oct 20, 2019 8:38 pm
- Forum: *Black Body Radiation
- Topic: Understanding Black Body Radiation
- Replies: 8
- Views: 665
Re: Understanding Black Body Radiation
Also, studies of black body radiation led to Planck's hypothesis of the quantization of electromagnetic radiation, which the photoelectric effect then provides evidence of the particle like properties of electromagnetic radiation. Black body radiation, therefore, helped guide research toward discove...
- Sun Oct 20, 2019 5:03 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Difference in Quantum Numbers?
- Replies: 2
- Views: 82
Re: Difference in Quantum Numbers?
The principal quantum number (n) refers to which energy level the electron is in (n=1,2,3,4..). With increasing principal energy levels, the electron gets farther from the nucleus. The angular momentum number (l) describes the shape of the orbital (s,p,d,f). The magnetic quantum number (ml) shows th...
- Thu Oct 17, 2019 6:17 pm
- Forum: *Shrodinger Equation
- Topic: Negative sign in Equation
- Replies: 4
- Views: 264
Negative sign in Equation
In class and the workshops, we looked at a diagram where the Y-axis is Energy, and the values are all negative building up to E=0 when the energy level goes toward infinity. Can someone explain why the energy values are negative? Is it due to the equation?
- Thu Oct 17, 2019 4:42 pm
- Forum: Properties of Light
- Topic: 1A7b textbook solution typo?
- Replies: 5
- Views: 187
Re: 1A7b textbook solution typo?
Dr. Lavelle has a page on his website that lists all the errors in the Solutions Manual! You can check there if you are questioning an answer as well!
- Thu Oct 17, 2019 4:35 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Nodal Planes
- Replies: 7
- Views: 363
Re: Nodal Planes
Hey! Is there any connection between the location of the nucleus and the nodal plane? Is the nucleus located on the nodal plane, since you cannot find an electron in the nucleus or the nodal plane?
- Sat Oct 12, 2019 6:28 pm
- Forum: DeBroglie Equation
- Topic: Mass of Protons, Neutrons, Electrons, Etc.
- Replies: 3
- Views: 73
Re: Mass of Protons, Neutrons, Electrons, Etc.
The value for the mass of the subatomic particles are given in the book and on the tests, the masses should be on the information sheet.
- Sat Oct 12, 2019 6:27 pm
- Forum: DeBroglie Equation
- Topic: Circular standing waves
- Replies: 4
- Views: 141
Re: Circular standing waves
I believe that the circular standing wave model represents how the electrons have quantized energy states in atoms. The electrons orbit the nucleus in waves in discrete distances from the nucleus. We cannot know exactly the position of the electron but it is orbiting somewhere in the realm of the ci...