CHEMISTRY COMMUNITY

Paula Sing 1J

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?

Paula Sing 1J

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.

Paula Sing 1J

What will we have to know about transition state theory for the final?

Paula Sing 1J

(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).

Paula Sing 1J

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.

Paula Sing 1J

The two half reactions given are:

Ag + I- ----> AgI + e- (anode) = -0.15 V
AgCl +e- ---> Ag + Cl- (cathode) = +0.22 V

Paula Sing 1J

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.

Paula Sing 1J

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 ...

Paula Sing 1J

Is there anything that isn't covered in our listed homework that we should review for the final?

Paula Sing 1J

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...

Paula Sing 1J

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.

Paula Sing 1J

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?

Paula Sing 1J

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...

Paula Sing 1J

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?

Paula Sing 1J

Which equations will we need to know how to derive for the final?

Paula Sing 1J

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?

Paula Sing 1J

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.

Paula Sing 1J

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?

Paula Sing 1J

Why are the answers for parts a and b both in J/mol? Shouldn't the answer just be in Joules of kilojoules?

Paula Sing 1J

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?

Paula Sing 1J

In homework problem 14.9 how are you supposed to determine the n value?

Paula Sing 1J

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...

Paula Sing 1J

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Paula Sing 1J

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...

Paula Sing 1J

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.

Paula Sing 1J

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.

Paula Sing 1J

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?

Paula Sing 1J

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?

Paula Sing 1J

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?

Paula Sing 1J

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&ved=2ahUKEwi__t_VlITZAhUO7GMKHZDODDwQjRx6BAgAEAY&url=https%3A%2F%2Fwww.spreadshirt.com.au%2Ffunny%2Bchemistry%2Bjoke%2Bthe%2Bbase%2Bis%2Bunder%2Bassault-A103640114&psig=AOvVaw3n_n74daEb98l5anYD9Pir&...

Paula Sing 1J

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.

Paula Sing 1J

How do you know when to use q=mc(delta)T vs when to use q=nc(delta)T?

Paula Sing 1J

How do you calculate the change in enthalpy of a phase change?

Paula Sing 1J

heheheheheheh

Paula Sing 1J

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?

Paula Sing 1J

CHEMISTRY COMMUNITY

Search found 36 matches

Rate law in multiple step reactions [ENDORSED]

Re: Bomb Calorimeter

Transition States

Re: 14.17

Re: 8.57

Re: Test 2 Question 8 wording

Re: flipping half reactions

8.57

what to study for the final

Re: Test 3 #5

Re: Functional Groups

Test 2 Question 8 wording

Test 2 Question 8

9.13

Derivations

14.7 part (c) [ENDORSED]

14.17

14.37 part a

Solution Manual 14.9 [ENDORSED]

Galvanic Cell vs. Daniell Cell [ENDORSED]

14.9

9.13 Gibbs free energy of formation

Re: Post All Chemistry Jokes Here

Re: Gas atoms

Re: Internal Energy in a Vacuum [ENDORSED]

Re: ideal cooler [ENDORSED]

Midterm

Standard State

Heat Capacity

Re: Post All Chemistry Jokes Here

HW 8.1

Calculating heat (q)

Calculating the Change in Enthalpy

Re: Post All Chemistry Jokes Here

Calorimeter vs. Bomb Calorimeter

Re: Post All Chemistry Jokes Here