Question

Answer what you can.


3. Which of the following statements is/are correct?
i. An object hanging motionless on a spring is in a static equilibrium
ii. In a dynamic equilibrium, the reversible changes occur continuously, even though there is no appearance of change
iii. The amounts of substances present in a system at equilibrium are equal
a. i only
b. ii only
c. iii only
d. i and ii
e. ii and iii


(i) correct (?)
(ii) correct as both sides of the equation are occuring simultaneously in equal order
(iii) correct as the amounts are equally proportionate

ACTUAL ANSWER:
(i) is wrong but the other two are correct ?

Answer 1

8. A molecular collision is sufficiently energetic to cause a reaction, yet no reaction occurs. Which of the following is the least likely explanation?
  a.  The proton–proton interaction is too large
  b.  The molecules have poor orientation
  c.  One of the molecules is not moving too slowly.
  d.  One or both the molecules does not have enough energy.
  e.  All of the above could be an explanation.

\(\color{steelblue}{\text{My answer}}\) E.
\(\color{red}{\text{Actual answer}}\) A.

Answer 2

For 8 the answer is straight forward: When you are looking at a chemical reaction proton-proton interactions are 100% irrelevant. In chemistry it is usually the electron repulsion and attraction that is relevant weather or not a chemical reaction can occur.

You can remember it like this: proton-proton interactions are relevant when you want to change the nuclei.

Answer 3

OH. I probably misread as "most likely"
my bad!

Answer 4

do you know about the other one though?

Answer 5

I am still thinking about it. Usually not working with static equilibria, so looking up some definitions.

Answer 6

also I think (c) is a typo, yes?

Answer 7

for 8. "is not moving too slowly" idk

Answer 8

Might be a typo, it could be a reference to it does not possess enough kinetic energy, at least that is what got to my mind when reading it.

Answer 9

hmm. maybe
ok and this one? we can skip 3 if it's too confusing

14. If a reaction is carried out in an aqueous solution, which of the following changes would not affect the rate of the reaction?
  a.  Increasing the temperature
  b.  Changing the concentration of reactants
  c.  Increasing the size of the reaction vessel
  d.  Adding a catalyst
  e.  More than one would not affect the rate of the reaction

so far my answer (♣) and actual answer (♦):

♣ A
♦ C

Answer 10

I know A is wrong because temperature DOES increase rate, but why is C right?

Answer 11

I don't know if the answer is as simple as: if you increase the size of the reaction vessel you lower the concentration of the reactants due to the reciprocal relationship between concentration and volume.

Answer 12

And you know from kinetics the rate depends on the concentration (in some cases)

Answer 13

Maybe because the equilibrium adjusts to the new size and is still proportional?

Answer 14

I mean, that sounds most reasonable

Answer 15

Except the equilibrium constant does not depend on the volume.

Answer 16

I didn't mean equilibrium constant though.

Answer 17

Yeah sorry also a bad argument. I don't think we can use equilibrium considerations here cause they are usually rapid. I think the best argument is due to concentration. Any non-zero order reaction would decrease in rate by increasing the volume.

Answer 18

Bad argument for what? I'm trying to prove that (c) "increasing the vessel size" would not affect rate

Answer 19

You kinda lost me... sorry

Answer 20

Oh not affect the rate... sorry I thought it would be decrease the rate... cause all the other reasons increase the rate.

Answer 21

So does the volume change affect rate? o_o

Answer 22

Theoretically I would guess yes. but the effect would be low, so no. :P I am a little unsure.

Answer 23

So not as much as the others. Or not noticeable.

That suits me just fine lol

Answer 24

24. If the position of equilibrium shifts to the left, what will happen?
  a.  The concentration of products will increase
  b.  The concentration of reactants will increase
  c.  The temperature will rise
  d.  The temperature will decrease
  e.  The concentrations of both products and reactants will increase

the answer is B but I'm not sure why.

Answer 25

if it shifts left... does that mean there are less products now?

Answer 26

Yes. So I think you should imagine their question like this: