GC question

[299678]

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is this just wrong answer or I am missing something

Q. which of the following will maximize the production of CO2 (g)?

2CO(g) + O2 (g) - 2CO2 (g) Delta H = - 566kj
a) removing O2
b) increasing the pressure
c) decreasing the temperature
d) decreasing the volume

Correct answer is c, but I think b, c, d are all correct

Q. which of the following will increase the yield of H2?
Mg^2+ (aq) + 2H+ (aq) - H2 (g) + Mg(s)

a) decreasing the pH
b) removing Mg(s)
c) removig Mg^2+
d) increasing the pressure

answer is a) but I think both a and d are correct

32) What is the pH of a solution that contains 0.05M HF and 0.05M NaF (Ka,HF = 6.8x10-4)?
A) 2.2
B) 2.9
C) 3.2
D) 4.2

 

[UndergradGuy7]

is this just wrong answer or I am missing something

Q. which of the following will maximize the production of CO2 (g)?

2CO(g) + O2 (g) - 2CO2 (g) Delta H = - 566kj
a) removing O2
b) increasing the pressure
c) decreasing the temperature
d) decreasing the volume

Correct answer is c, but I think b, c, d are all correct

Q. which of the following will increase the yield of H2?
Mg^2+ (aq) + 2H+ (aq) - H2 (g) + Mg(s)

a) decreasing the pH
b) removing Mg(s)
c) removig Mg^2+
d) increasing the pressure

answer is a) but I think both a and d are correct

Question 1 uses Le'Chatlier's principle.

Assume 2CO(g) + O2 (g) -> 2CO2 (g) is at equilibrium. We have some CO, O2 and CO2. If we take away O2 as in choice A, then the equilibrium will shift towards the left. This uses the CO2 to make O2 and CO. So A is wrong.

For choice b, you need to count the moles on each side. Left side is 2 moles of CO and 1 mole of O2. Right side is 2 moles of CO2. If you increase the pressure, you shift towards the side with less moles. So towards CO2.

Choice c, we can write the equation as 2CO(g) + O2 (g) -> 2CO2 (g) + heat, since the enthalpy is negative. So we decrease the temperature, it will shift towards the right.

Choice d, decreasing the volume is the same as increasing the pressure. So again it will shift towards the side with less moles or towards the right side.

So I guess B, C, and D are all right?


For question 2, A is correct. B is not correct because the solid is not part of the equilibrium expression, right?
C is wrong.
D is also wrong because we only have 1 gas on the right which is H2. Increasing the pressure would shift the equilibrium towards the side with less moles of gas. This is the left side. The left side has no moles of gases. I think you tried to count the moles on each side, but this is not right because the volume of aq, s, and l are not that big compared to gases so we ignore them.

 

[qkchen]

is this just wrong answer or I am missing something

Q. which of the following will maximize the production of CO2 (g)?

2CO(g) + O2 (g) - 2CO2 (g) Delta H = - 566kj
a) removing O2
b) increasing the pressure
c) decreasing the temperature
d) decreasing the volume

Correct answer is c, but I think b, c, d are all correct

Q. which of the following will increase the yield of H2?
Mg^2+ (aq) + 2H+ (aq) - H2 (g) + Mg(s)

a) decreasing the pH
b) removing Mg(s)
c) removig Mg^2+
d) increasing the pressure

answer is a) but I think both a and d are correct

32) What is the pH of a solution that contains 0.05M HF and 0.05M NaF (Ka,HF = 6.8x10-4)?
A) 2.2
B) 2.9
C) 3.2
D) 4.2

what is the answer for 32), is it C) 3.2?

 

[UndergradGuy7]

what is the answer for 32), is it C) 3.2?

That is what I got.

It is a buffer problem.

ph = pka + log (F-/HF)

F-/HF = 1

ph = 3.167 + log 1
ph = 3.167