Photon336 one year ago Chem-question

1. Photon336

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2. Photon336

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3. Photon336

318

4. sweetburger

5. Photon336

@sweetburger because it's at equilibrium already can we assume that it's saturated solution if so then adding more NaCN would precipitate in my opinion

6. sweetburger

Agreed

7. Photon336

yes it's B

8. sweetburger

For 320 [.2]^2/([.1][.2])= 2=Keq

9. sweetburger

So 320 is B. I think.

10. Photon336

319. we have $N _{2} + O _{2} --> 2NO$

11. Photon336

319. A. equilibrium constant is temperatuer dependent so if we changed the temperature we should also change the equilibrium concentrations because we would have a new Keq value. C adding more NO will shift to the reactants if it's already at equilibrium D N2 we don't know if we added or removed it but that would cause a shift. B. is the answer because if we have the same number of moles on either side of the equation increasing the pressure does not cause any change in the equlibrium concentrations. remember increase in pressure favors the side with fewer number of moles , while decreasing pressure it's the opposite.

12. sweetburger

Completely agreed.

13. sweetburger

318. Adding a Catalyst would lower the activation energy of the reaction which in turn would increase the rate of the forward reaction, but would also increase the rate of the reverse reaction as the activation energy of the reverse reaction is also lowered showed in this diagram below.|dw:1438548218094:dw|

14. sweetburger

So adding a catalyst would have minimal affect on the equilibrium concentrations.

15. sweetburger

effect*

16. Photon336

yeah that's a great way to explain that.

17. Photon336

$K _{eq} = \frac{ [0.20]^{2} }{ [0.20][0.10] } = 2$ for the other one like they gave us equilibrium concentrations so we didn't have to do that ICE table stuff.

18. sweetburger

Haha, the ICE Table is very annoying to write out...

19. Photon336

I hate. that..

20. Photon336

287. A. magnitude of the activation energy, the higher the Ea the harder it will be to get the reaction going. B.(nope) this is our answer C. lowering activation energy is what a catalyst does and that increases the rate of the reaction. D. absolute temperature yes. because increasing temperature increase the rate of our reaction $k = Ae ^{Ea/RT}$ you increase the temperature and lower Ea the k value goes up. so B for 287

21. Photon336

286/288 left

22. sweetburger

Ahh i see it now. I was somewhat confused on question 287, but you clarified it quite nicely.

23. Photon336

thanks haha

24. sweetburger

For 286. I'm not sure, but I am leaning towards answer choice D. I think answer choices A and C are effectively the same in which the same process is occurring in which the activation energy is being lowered. I know that increasing the temperature does indeed effect the rate constant. TBH I thought that only temperature truly could change the rate constant.

25. Photon336

288. A. $-\frac{ 1 }{ 2 } \frac{ \Delta [KMnO _{4}] }{ \Delta T}$

26. Photon336

288. Notice that once Mn forms the reaction is now fast. to write our rate law our reaction is going to depend on our slowest step. so that's how I eliminated C and D. now for A and B. we know that in our rate law, our concentration of [KMnO4] is going to decrease and when you write the integrated rate law the coefficients let' say two becomes (1/2) so that eliminates B.

27. Photon336

that's why we consider KMnO4 and not MnSO4

28. Photon336

for 286 i agree with you.. that's funny because whenever two answers are the same they can't be the answer they are looking for

29. sweetburger

Yea I agree with your thought process on question 288.

30. Photon336

did they teach you this equation $k = Ae ^{Ea/RT}$

31. sweetburger

That is the Arrenhius? If i remember.

32. Photon336

yeah

33. sweetburger

I have to go, but I will gladly help anytime.

34. Photon336

also $r = k[A]^{x}[B]^{y}$

35. Photon336

it's d doubling the concentration of one of the reactatns

36. Photon336

that affects the rate of the reaction but not the rate constant k

37. sweetburger

Ahh so for 286 the answer was D?

38. Photon336

yep

39. Photon336

Anyway I have to go cya around

40. sweetburger

Now looking at the Arrenhius I see how obvious it is XD *facepalm*

41. Photon336

=D

42. sweetburger

Alrighty seeya :)