Search found 30 matches

by Michelle Song 1G
Fri Mar 15, 2019 3:04 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Does a -E and -G mean that the reverse reaction is spontaneous? [ENDORSED]
Replies: 3
Views: 220

Re: Does a -E and -G mean that the reverse reaction is spontaneous? [ENDORSED]

Is the reverse also true? Does a +G mean that the forward reaction is nonspontaneous but the reverse reaction is spontaneous?
by Michelle Song 1G
Tue Mar 12, 2019 6:12 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6.57
Replies: 2
Views: 40

6.57

Can someone please explain how to find the cathode and why which equation is the cathode/anode?

The solutions manual says that the reduction of F2 is the cathode even though its reduction potential is lower than that of the supposed anode.
by Michelle Song 1G
Tue Mar 12, 2019 4:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test 2 #5
Replies: 1
Views: 42

Test 2 #5

Once you get K2 do you
1. take the square root of it to find [H3O+] and assume that [H3O+] = [OH-] and get the pH from there

2. put 10^-7 as [H3O+] because the pH is 7 and divide K2 by that to get [OH-] and see which one is higher to decide if it's acidic or basic?
by Michelle Song 1G
Tue Mar 12, 2019 4:28 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Test 2: Why is photosynthesis spontaneous?
Replies: 2
Views: 201

Test 2: Why is photosynthesis spontaneous?

Here is the exact statement:

The photosynthesis of glucose inside the chloroplast of an old growth Coastal Redwood tree.

I said deltaG > 0 and got it wrong.
by Michelle Song 1G
Tue Feb 26, 2019 3:56 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Lyndon's Worksheet #3
Replies: 1
Views: 93

Lyndon's Worksheet #3

I'm confused why you can't add the two reactions to make a new reaction and have to convert to G. I thought that was how all redox reactions were solved and I don't understand why this reaction is different.
by Michelle Song 1G
Sun Feb 24, 2019 8:57 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.5d
Replies: 1
Views: 37

6L.5d

Why is the oxidation equation Au(s) -> Au3+(aq) + 3e- and not Au+(aq) -> Au3+(aq) + 3e-?
by Michelle Song 1G
Sun Feb 24, 2019 8:44 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Adding an inert electrode? 6L.5b
Replies: 1
Views: 31

Adding an inert electrode? 6L.5b

How do you know when you have to add another element that's not given in the equation into the cell diagram? The solutions manual says that "an inert electrode such as Pt is necessary when both oxidized and reduced species are in the same solution" but I don't understand what that means an...
by Michelle Song 1G
Sun Feb 24, 2019 1:37 pm
Forum: Balancing Redox Reactions
Topic: 6K.3d
Replies: 2
Views: 44

Re: 6K.3d

How do you know that Cl2 goes to Cl- when it's not listed in the equation?
by Michelle Song 1G
Sat Feb 23, 2019 8:25 pm
Forum: Balancing Redox Reactions
Topic: 6K.3d
Replies: 2
Views: 44

6K.3d

How do you find the half reactions?
by Michelle Song 1G
Sat Feb 09, 2019 3:22 pm
Forum: Phase Changes & Related Calculations
Topic: Why does steam cause severe burns?
Replies: 2
Views: 46

Why does steam cause severe burns?

Sorry, I realize that Dr. Lavelle has gone over this in class but I didn't really understand his explanation.
by Michelle Song 1G
Sat Feb 09, 2019 3:16 pm
Forum: Administrative Questions and Class Announcements
Topic: Textbook glitch
Replies: 2
Views: 84

Textbook glitch

Is anyone else's online textbook missing a lot of numbers from the problems? I try to deduce the numbers from the solutions manual but it can get really frustrating having to do it every time... is there any way I can fix this?
by Michelle Song 1G
Tue Jan 29, 2019 6:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.23
Replies: 1
Views: 29

Re: 4D.23

Also,

-169.2 kJ = deltaH (N2O5) - 2(+90.25 kJ)

Why doesn't -169.2 kJ equal delta H(N2O5)? Why do you have to add 2(+90.25 kJ)?
by Michelle Song 1G
Tue Jan 29, 2019 6:50 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.23
Replies: 1
Views: 29

4D.23

How do you come up with the reaction equation N2 (g) + 5/2 O2 (g) -> N2O5 (g) ?
by Michelle Song 1G
Tue Jan 29, 2019 6:37 pm
Forum: Phase Changes & Related Calculations
Topic: 4B.13b
Replies: 1
Views: 43

4B.13b

Why do you have to take the natural log of V2/V1?
by Michelle Song 1G
Tue Jan 29, 2019 6:27 pm
Forum: Phase Changes & Related Calculations
Topic: 4B.13a
Replies: 1
Views: 43

4B.13a

The solutions manual states that the equation for the irreversible work of expansion against a constant opposing pressure is given by w= -P delta V. Why do you have to multiple the result by 101.325 J.L^-1.atm^-1?
by Michelle Song 1G
Sun Jan 27, 2019 11:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE BOX and coefficients
Replies: 4
Views: 62

Re: ICE BOX and coefficients

When there are coefficients in front of the molecules you multiply it by x (the change).
by Michelle Song 1G
Tue Jan 22, 2019 9:27 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Does [H3O+][OH-] always equal 10^-14?
Replies: 9
Views: 145

Does [H3O+][OH-] always equal 10^-14?

Under what conditions does it not equal 10^-14? For 6B.9 [H3O+][OH-] does not equal 10^-14...
by Michelle Song 1G
Mon Jan 21, 2019 12:43 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: pKa and pKb
Replies: 3
Views: 220

pKa and pKb

The textbook says that the weaker the acid, the smaller the value of Ka and the greater the value of pKa. If I'm interpreting this correctly, it makes sense that a weak acid would have a greater number on the pH scale because the lower the number the more acidic and the greater the number the more b...
by Michelle Song 1G
Thu Jan 17, 2019 8:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: [H3O+] =[OH-]
Replies: 2
Views: 74

Re: [H3O+] =[OH-]

[H3O+][OH-] = 10^-14
If [H3O+] =[OH-], then they both equal 10^-7. pH = -log [H3O+] = -log[10^-7] = 7 so the solution is neutral.
by Michelle Song 1G
Thu Jan 17, 2019 12:15 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Why do stronger bases have conjugate acids with larger pKa values?
Replies: 4
Views: 75

Why do stronger bases have conjugate acids with larger pKa values?

Professor Lavelle said in class that strong bases have weak conjugate acids and weak bases have strong conjugate bases. I don't understand why and I also don't understand why stronger bases have conjugate acids with larger pKa values.
by Michelle Song 1G
Wed Jan 16, 2019 11:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6B.11
Replies: 2
Views: 57

6B.11

For part ii of a, how do you figure out the concentration of OH- from the original solution? The solutions manual says to multiple the concentration of OH- in the diluted solution by 500.0 mL/5.00 mL but I don't understand why.
by Michelle Song 1G
Thu Jan 10, 2019 10:41 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5.33
Replies: 2
Views: 45

Re: 5.33

Also, why does decreasing the volume favor the formation of X2? I understand that decreasing the volume increases the pressure but I do not understand why this would lead to an increase in reactants.
by Michelle Song 1G
Thu Jan 10, 2019 10:32 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5.33
Replies: 2
Views: 45

5.33

According to the solutions manual, the answer is a because the reaction is endothermic. The solutions manual says that the value of the equilibrium constant is larger in Flask 2 than in Flask 1, which is consistent with an increase in temperature of an endothermic reaction. I do not understand why a...
by Michelle Song 1G
Wed Jan 09, 2019 5:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.9c, d, e
Replies: 2
Views: 50

5G.9c, d, e

A 0.10-mol sample of pure ozone, O3, is placed in a sealed 1.0-L container and the reaction 2O3 (g) -> 3O2(g) is allowed to reach equilibrium. A 0.50-mol sample of pure ozone is placed in a second 1.0-L container at the same temperature and allowed to reach equilibrium. Without doing any calculation...

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