## Search found 36 matches

Sat Mar 17, 2018 12:37 am
Forum: Experimental Details
Topic: Rate law in multiple step reactions [ENDORSED]
Replies: 3
Views: 435

### Rate law in multiple step reactions[ENDORSED]

How are we supposed to differentiate the cases in which the overall rate law is equal to the rate law of the slow step vs when it is not?
Sat Mar 17, 2018 12:23 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Bomb Calorimeter
Replies: 6
Views: 410

### Re: Bomb Calorimeter

A bomb calorimeter is like a regular a calorimeter except a bomb calorimeter is an isolated system which is sealed and thus provides constant pressure and volume.
Sat Mar 17, 2018 12:18 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Transition States
Replies: 1
Views: 95

### Transition States

What will we have to know about transition state theory for the final?
Sat Mar 17, 2018 12:14 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.17
Replies: 2
Views: 130

### Re: 14.17

(a) Write balanced half-reactions for the redox reaction of an acidified solution of potassium permanganate and iron(III) chloride.
(b) Write the balanced equation for the cell reaction and devise a galvanic cell to study the reaction (write its cell diagram).
Sat Mar 17, 2018 12:11 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.57
Replies: 2
Views: 209

### Re: 8.57

Why does the fact that the chemical equation is a combustion reaction mean that you do reactants - products instead of the other way around? I thought the only time you do reactants minus products is when you are dealing with bond enthalpies.
Sat Mar 17, 2018 12:08 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Test 2 Question 8 wording
Replies: 3
Views: 236

### Re: Test 2 Question 8 wording

The two half reactions given are:

Ag + I- ----> AgI + e- (anode) = -0.15 V
AgCl +e- ---> Ag + Cl- (cathode) = +0.22 V
Fri Mar 16, 2018 11:52 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: flipping half reactions
Replies: 2
Views: 174

### Re: flipping half reactions

Because we usually assume that the overall E(cell) value should be favorable, meaning the value is positive, you would want to flip the equation that has the smaller (or more negative) E(cell) value and make that the anode.
Fri Mar 16, 2018 11:48 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.57
Replies: 2
Views: 209

### 8.57

My first intuition in solving this problem is to do enthalpy of products minus the enthalpy of reactants, and I get the correct number when I solve it this way only the sign is wrong ( + instead of -). The book solves this by coming up with a bunch of intermediary reactions that add up to the final ...
Fri Mar 16, 2018 11:40 pm
Forum: Student Social/Study Group
Topic: what to study for the final
Replies: 1
Views: 269

### what to study for the final

Is there anything that isn't covered in our listed homework that we should review for the final?
Fri Mar 16, 2018 11:34 pm
Forum: General Rate Laws
Topic: Test 3 #5
Replies: 1
Views: 83

### Re: Test 3 #5

First you need to solve for the molarities of NO and O2. You are given the weight in grams of each so you divide by their respective molar masses to get moles of each compound then you divide each by .75L to make the values a concentration in molarity. You would then plug in these values you have in...
Fri Mar 16, 2018 11:29 pm
Forum: *Carboxylic Acids
Topic: Functional Groups
Replies: 4
Views: 776

### Re: Functional Groups

I don't think we will necessarily have to know how to draw the functional groups, but we will probably need to be able to identify them in a given structure.
Fri Mar 16, 2018 11:26 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Test 2 Question 8 wording
Replies: 3
Views: 236

### Test 2 Question 8 wording

In question 8 it says that the following half-reactions are unbalanced, but their charges and the moles of each atom are equal on either side, so how are they unbalanced?
Fri Mar 16, 2018 11:22 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Test 2 Question 8
Replies: 1
Views: 200

### Test 2 Question 8

For part c of this problem when you calculate the E(cell) value, I know it's usually cathode minus anode, but that is when you are working with two reduction potential. In the problem you are given an oxidation potential and a reduction potential, so I added the two together (0.22+ (-)0.15)= 0.07 bu...
Fri Mar 16, 2018 11:13 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.13
Replies: 2
Views: 229

### 9.13

In this question I understand that you can use delta S=nRln(V2/V1) for the first part of the problem, but how are you supposed to know to use S=nRln(T2/T1) instead of delta S=nCln(T2/T1) with the C-value calculated for constant volume?
Fri Mar 16, 2018 11:06 pm
Forum: Administrative Questions and Class Announcements
Topic: Derivations
Replies: 2
Views: 203

### Derivations

Which equations will we need to know how to derive for the final?
Mon Feb 26, 2018 1:53 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 14.7 part (c) [ENDORSED]
Replies: 1
Views: 124

### 14.7 part (c)[ENDORSED]

Can someone explain why it is okay for calculate the Q value by combining the pressures and molarities and just canceling out their units. Isn't there some type of conversion that has to be done? Shouldn't the values used to calculate Q be in the same units?
Mon Feb 26, 2018 1:45 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.17
Replies: 2
Views: 130

### 14.17

Could someone walk me through this problem? I'm not sure how to set it up or how you're supposed to know which half reactions to write from the information given.
Mon Feb 26, 2018 1:42 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 14.37 part a
Replies: 2
Views: 98

### 14.37 part a

When calculating the cell potential of the cell given in part (a) why are you allowed to omit Cl as is shown in the solutions manual?
Wed Feb 21, 2018 4:25 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Solution Manual 14.9 [ENDORSED]
Replies: 1
Views: 84

### Solution Manual 14.9[ENDORSED]

Why are the answers for parts a and b both in J/mol? Shouldn't the answer just be in Joules of kilojoules?
Wed Feb 21, 2018 2:45 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic Cell vs. Daniell Cell [ENDORSED]
Replies: 1
Views: 70

### Galvanic Cell vs. Daniell Cell[ENDORSED]

What is the difference between a Galvanic Cell and a Daniell Cell? Is there any difference in how you solve problems if it is a Daniell cell vs. a normal Galvanic cell?
Thu Feb 15, 2018 5:58 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.9
Replies: 2
Views: 111

### 14.9

In homework problem 14.9 how are you supposed to determine the n value?
Sat Feb 10, 2018 6:04 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 9.13 Gibbs free energy of formation
Replies: 1
Views: 91

### 9.13 Gibbs free energy of formation

In the last paragraph on page 353, it says " A thermodynamically stable compound is a compound with a negative standard Gibbs free energy of formation. A thermodynamically unstable compound is a compound with a positive standard Gibbs free energy of formation." Why is this so if when delta...
Wed Jan 31, 2018 11:49 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7664
Views: 1035877

### Re: Post All Chemistry Jokes Here

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Wed Jan 31, 2018 11:47 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: Gas atoms
Replies: 4
Views: 167

### Re: Gas atoms

A real life example of this that might help you understand this would be spraying perfume in the corner of a room. It is "spontaneous" for the scent molecules to disperse throughout the room rather than to stay only in the corner. It is a lot like the diffusion of water across a membrane i...
Wed Jan 31, 2018 11:38 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Internal Energy in a Vacuum [ENDORSED]
Replies: 5
Views: 243

### Re: Internal Energy in a Vacuum[ENDORSED]

I think that the idea of a vacuum is that there is no pressure in the system, thus the energy change is zero because in the equation w=-p(delta)t the value for p is always zero, so q=0 as well.
Wed Jan 31, 2018 11:34 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: ideal cooler [ENDORSED]
Replies: 5
Views: 262

### Re: ideal cooler[ENDORSED]

I agree, I think that the idea with this and the inclusion of the word "ideal" alludes to the fact that this "cooler" works very well, such that the system can be acknowledged as isolated.
Wed Jan 31, 2018 11:32 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Midterm
Replies: 6
Views: 241

### Midterm

Will the Midterm be a cumulative test over chapter 8 and 9? If so will the questions be more conceptual like on test one or will they be more problem solving based problems like in the homework?
Wed Jan 31, 2018 11:20 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Standard State
Replies: 2
Views: 130

### Standard State

Are we supposed to memorize the standard states of certain compounds or is there a way to determine this which can be applied to all?
Wed Jan 31, 2018 11:15 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity
Replies: 3
Views: 152

### Heat Capacity

If for example there is a problem about dropping a metal at one temperature into a cup with water at a different temperature are we to assume that at equilibrium the final temperature of the metal is equal to the temperature of the water?
Wed Jan 31, 2018 11:10 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7664
Views: 1035877

### Re: Post All Chemistry Jokes Here

Wed Jan 24, 2018 11:16 pm
Forum: Phase Changes & Related Calculations
Topic: HW 8.1
Replies: 3
Views: 161

### HW 8.1

Can someone explain how gasoline burning in an automobile engine is an open system, because to me it seems that it should be closed because the gas combusts within the engine which is in my mind a closed space.
Wed Jan 24, 2018 11:07 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calculating heat (q)
Replies: 4
Views: 355

### Calculating heat (q)

How do you know when to use q=mc(delta)T vs when to use q=nc(delta)T?
Wed Jan 24, 2018 11:02 pm
Forum: Phase Changes & Related Calculations
Topic: Calculating the Change in Enthalpy
Replies: 4
Views: 182

### Calculating the Change in Enthalpy

How do you calculate the change in enthalpy of a phase change?
Wed Jan 24, 2018 10:56 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7664
Views: 1035877

### Re: Post All Chemistry Jokes Here

heheheheheheh
Fri Jan 19, 2018 11:41 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeter vs. Bomb Calorimeter
Replies: 2
Views: 122

### Calorimeter vs. Bomb Calorimeter

What is the difference between these two types of calorimeters? How is it reflected when calculating how much heat is released from any given reaction?
Fri Jan 19, 2018 11:28 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7664
Views: 1035877