## Search found 33 matches

Fri Mar 15, 2019 11:17 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Rate of formation, rate in terms of loss
Replies: 3
Views: 169

### Rate of formation, rate in terms of loss

If we are given 2A --> B + C for example, if the questions says that the rate of formation of B is ______, then is that the same as saying the rate in terms of loss of A is _______? In other words, do those two phrases equal the same rate.
Fri Mar 15, 2019 11:07 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell diagram from lecture problem
Replies: 2
Views: 144

### Cell diagram from lecture problem

I'm still a bit confused on the cell diagram Ag(s)|AgBr(s)||Br-(aq)|Br2(g)|Pt(s)
I understand that there is no comma in between Ag(s) and AgBr(s) because two solids cannot be mixed, but why is AgBr(s) in the oxidation half of the cell diagram instead of just Ag+(aq)?
Fri Mar 15, 2019 5:19 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Finding reverse activation energy
Replies: 1
Views: 380

### Finding reverse activation energy

How do you calculate the reverse activation energy or reactions? And is calculating the reverse activation energy for an endothermic and exothermic reaction different?
Mon Mar 04, 2019 9:47 pm
Forum: General Rate Laws
Topic: rate and dependence on [R]
Replies: 2
Views: 95

### rate and dependence on [R]

I just wanted to ask this question for clarification.
I know that initial reaction rates only depend on [R].
So, reaction rates also only depend on [R]?
Mon Mar 04, 2019 5:20 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Dilution effect on cell potential
Replies: 1
Views: 101

### Dilution effect on cell potential

Why is it that if you add water to the anode compartment, dilution of the anode would increase cell potential?
(this is 14.93 part b)
Mon Mar 04, 2019 5:11 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: electrolytic cell
Replies: 4
Views: 472

### Re: electrolytic cell

You will have a negative Ecell for an electrolytic cell because electrolysis is when you use an electric current in an electrolytic cell to drive a NON-spontaneous redox reaction.
-Ecell denotes a non-spontaneous reaction.
Wed Feb 27, 2019 10:19 am
Forum: Balancing Redox Reactions
Topic: Aq to Aq or S to Aq (14.13d) [ENDORSED]
Replies: 2
Views: 148

### Aq to Aq or S to Aq (14.13d)[ENDORSED]

The equation given is Au+(aq) -> Au(s) + Au3+ (aq)
The anode reaction is Au(s) -> Au3+(aq) + 3e- but why is the anode reaction not Au+(aq) -> Au3+ 2e-
Tue Feb 26, 2019 4:18 pm
Forum: Balancing Redox Reactions
Topic: Substance reduced or oxidized? (14.17)
Replies: 2
Views: 108

### Re: Substance reduced or oxidized? (14.17)

In the question you are only given "Write balanced half-reactions for the redox reaction of an acidified solution of potassium permanganate and iron(II) chloride." So without the reaction I'm confused on how to determine which substance would oxidize and which would reduce.
Tue Feb 26, 2019 4:03 pm
Forum: Balancing Redox Reactions
Topic: Substance reduced or oxidized? (14.17)
Replies: 2
Views: 108

### Substance reduced or oxidized? (14.17)

When you are not specifically told which element is being oxidized or which is reduced nor are you given any reaction, how do you know which substance will be oxidized and which will be reduced? Like in the question you are simply told that KMnO4 and FeCl2 are both in an acidified solution. The answ...
Tue Feb 26, 2019 3:58 pm
Forum: Balancing Redox Reactions
Topic: Cell Diagram
Replies: 4
Views: 171

### Re: Cell Diagram

For a side that lacks a solid conductor, add Pt(s) to that side. This is the inert conductor you should use as the electrode to transfer electrons.
Mon Feb 25, 2019 11:41 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: single vertical line (l) and comma (,)
Replies: 1
Views: 60

### single vertical line (l) and comma (,)

Sometimes in the homework there is a comma not a vertical line between the two species. Is this because the comma separates the species that are in the same phase? And the vertical line separates the species in different phases?
Mon Feb 25, 2019 11:00 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: E ˚ sign for reaction to occur
Replies: 1
Views: 99

### E ˚ sign for reaction to occur

For the reaction to occur does E ˚ have to be positive?
Fri Feb 22, 2019 5:33 pm
Forum: Balancing Redox Reactions
Topic: Balancing problem
Replies: 3
Views: 166

### Re: Balancing problem

Basically the Cl2 is both the oxidizing and reducing agent. The charge of Cl in Cl2(s) is 0, in HClO the charge of Cl is +1, in Cl- the charge of Cl is -1.
Fri Feb 22, 2019 3:55 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: -charge x E = Wmax
Replies: 2
Views: 115

### Re: -charge x E = Wmax

You have max work because you are using max potential (E). The battery (system) is doing work, so the amount of energy that leaves the system basically makes it negative w (-w).
Fri Feb 22, 2019 3:25 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cathode vs. Anode
Replies: 9
Views: 322

### Re: Cathode vs. Anode

The cathode is the reduction half of the cell and the anode is the oxidation half of the cell. Cathode= reduction half reaction. Anode= oxidation half reaction.
Fri Feb 22, 2019 3:22 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Porous Disc
Replies: 2
Views: 133

### Re: Porous Disc

It seems that the main difference is that a salt bridge connects the anode and cathode in separate beakers and allows ions to flow between the solutions while a porous disk does not allow the solutions to mix. However in both cases, ions flow.
Sun Feb 17, 2019 11:43 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 8
Views: 350

### Re: Bond Enthalpies

It takes more energy to break the bonds, thus breaking the bonds is an endothermic reaction. Forming is the bonds is an exothermic reaction, so the equation to find the total bond enthalpy is in the fact bonds broken - bonds formed.
Sun Feb 17, 2019 11:37 am
Forum: Phase Changes & Related Calculations
Topic: Chapter 8 number 21
Replies: 4
Views: 191

### Re: Chapter 8 number 21

Whatever is lost by the system is gained by the surroundings. Which side of the equation you place the negative sign thus doesn't matter, you just have to make sure one side has the negative sign and the other does not.
Sat Feb 09, 2019 6:00 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 6th edition 9.15; standard conditions? (Degree symbol)
Replies: 1
Views: 102

### 6th edition 9.15; standard conditions? (Degree symbol)

I get that if deltaS or deltaH has a degree symbol then it means that the measurement was made under standard conditions. How come in the solutions manual for 9.15 in part a there is degree symbol and in part b there isn't?
Is there a specific reason for this?
Fri Feb 08, 2019 11:16 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 6th edition Question 8.67
Replies: 2
Views: 165

### Re: 6th edition Question 8.67

To find the enthalpy of formation in the liquid state you need to take the the deltaH you calculated for the gas and then add the negative value of the enthalpy of vaporization from it. The value is negative because instead of the positive value you have when finding how much energy must be added to...
Sat Feb 02, 2019 6:47 pm
Forum: Calculating Work of Expansion
Topic: Maximum expansion work?
Replies: 2
Views: 109

### Re: Maximum expansion work?

With reversible expansion, you can basically think of the system at equilibrium, with changes only occurring in really small steps. Maximum expansion work is occurring because the inside is pushing against the greatest possible external pressure. This work is maximum expansion work.
Tue Jan 29, 2019 8:05 pm
Forum: Calculating Work of Expansion
Topic: Irreversible and reversible expansion, 6th edition 8.11
Replies: 2
Views: 116

### Irreversible and reversible expansion, 6th edition 8.11

Do you know if a process is an irreversible expansion if you relatively come to the same original volume value? I'm confused as to how we know from information given whether or not a process is reversible or irreversible. I feel that (a) and (b) given are switched in the solutions manual, or am I ju...
Tue Jan 22, 2019 9:42 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier and water
Replies: 3
Views: 145

### Le Chatelier and water

If you add water, does this effect in whether reaction will form reactant and product? Same for if you remove water, because water is a liquid, so does it have an effect on K.
Mon Jan 21, 2019 10:32 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6th edition 12.69 Ka
Replies: 3
Views: 169

### 6th edition 12.69 Ka

Does anyone know where the Ka value of 1.4x10^-5 came from for Al(H2O)5OH2+?
Sun Jan 20, 2019 10:53 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Lecture 1/18/19
Replies: 1
Views: 69

### Re: Lecture 1/18/19

You know that you started off with 0.150M of NO2- given that you had 0.150M of KNO2. The initial concentration then of NO2- will be 0.150M. Because initially there is no reaction occurring, there are no H3O+ molecules yet that formed from the deprotonation of HNO2. So, you start with 0 for H3o+ and ...
Sun Jan 20, 2019 6:02 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 12.69 6th edition AlCl3 equation
Replies: 1
Views: 34

### 12.69 6th edition AlCl3 equation

For this problem, it is asking to find the pH of an AlCl3 solution, but I'm not too sure if I'm setting up the equation correctly. Is
AlCl3 + 3H2O -> Al(OH)3 + 3HCl correct?
From here, do you figure that the HCl would completely dissociate?
Sun Jan 20, 2019 5:47 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Biological Examples
Replies: 1
Views: 84

### Re: Biological Examples

I think this is just referring to being able to understand any problems given in finding initial and equilibrium concentrations. In lecture 2, Lavelle gave an example using ATP hydrolysis in order to find equilibrium concentrations.
Wed Jan 16, 2019 11:26 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test 1 topics
Replies: 1
Views: 45

### Test 1 topics

We're going to be tested on equilibrium, acid and base equilibria, and acids and bases right (basically Outline 1 and Outline 2)? Just double checking to see that we won't be tested on thermochemistry yet.
Wed Jan 16, 2019 11:23 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Cations as acids
Replies: 2
Views: 79

### Re: Cations as acids

Small highly charged metal cations can produce acidic solutions. These cations are basically those with a charge of 3+ for example. These small cations can exert the greatest pull on the electrons in surrounding H20 molecules, resulting in a greater number of hydrogen ions to be lost from the water ...
Wed Jan 16, 2019 11:16 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Converting Between Kp and Kc
Replies: 3
Views: 112

### Re: Converting Between Kp and Kc

I believe is just depends on the information that is given in the problem. If you are given equilibrium pressure values, use Kp and if given equilibrium concentration values, use Kc. They each give you the equilibrium constant, K.
Thu Jan 10, 2019 1:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Keq vs. Kc vs. Kp
Replies: 3
Views: 6076

### Re: Keq vs. Kc vs. Kp

Keq is the general equilibrium constant as you mentioned. Kc refers to when you are using the equilibrium concentration values to find the Keq value and Kp refers to when you are using the equilibrium partial pressures values to find the Keq value!
Thu Jan 10, 2019 1:07 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Chemical Equilibrium Part 2 Question 19
Replies: 2
Views: 110

### Re: Chemical Equilibrium Part 2 Question 19

Don't forget that you don't take solids into consideration when you are trying to find the value of the reaction quotient Q. Also, because they give you that you account for the gases in a 3.00L vessel, you should divide all of the moles by this 3.00L value. You should end up with Q= ((1.23x10^-3)/3...
Wed Jan 09, 2019 9:12 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Difference between brackets and parentheses?
Replies: 4
Views: 678

### Re: Difference between brackets and parentheses?

Brackets are used when referring to concentration amounts. However, once you start calculating K or Kc, although we use concentration amounts to obtain the equilibrium constant, using concentration is still an approximation. We are actually trying to find equilibrium constant using chemical activity...