Chem Exam

[Blessing34]

Hi
can someone please tell me
what were we meant to write for the equilibrium question,
for effect on temperature and pressure

[ActivationEnergy]

Hi
can someone please tell me
what were we meant to write for the equilibrium question,
for effect on temperature and pressure

I wrote about the effect of the increase and decrease of temperature and pressure on the yield of the product and you had to do this by referring to Le Chatelier's principle. So basically acknowledging that the system is exothermic and how it will partially oppose the changes of an increase/decrease of temperature and pressure.

[AR1472]

https://mp.weixin.qq.com/s/e8WwrED428ZGyTiJisOLdQ
hopefully it can be opened
don't care about the answers they provided

hi with these answers, what did people write for SAQ 4)d? they haven't written anything for this

[Blessing34]

I wrote about the effect of the increase and decrease of temperature and pressure on the yield of the product and you had to do this by referring to Le Chatelier's principle. So basically acknowledging that the system is exothermic and how it will partially oppose the changes of an increase/decrease of temperature and pressure.

Thank you,
i acknowledged that it was exothermic and only wrote about the effect on the increase in temperature. and with pressure i said if it is increased and how it is opposed by LCP

[AR1472]

also, for 7)c.i i got 800g/mol. if i used that value in 7)c.ii would i get consequential marks?

[keltingmeith]

For question 6 I put B? the half cells for electrolytic threw me off 

Must preface this with an apology - electrochem is not my best area!

When they say half-cell, it doesn't just mean the electrodes. It also means the components of each half-cell, such as the electrolyte, the rest of the environment, etc. And, it is true that the products MUST depend on all of those things, otherwise you're making something out of nothing. And, chemical energy->electrical energy is the whole point of a galvanic cell, hence why D is correct.

As for B - it is wrong because the electrolyte concentration can and will affect the amount of energy that comes out. You've learned how to calculate the energy for a Galvanic cell purely for a cell in standard conditions - 25 degrees C, 1 atm of pressure, and with concentrations of all components of 0.1 M. Things become more complicated when ANY of those things change.

hi with these answers, what did people write for SAQ 4)d? they haven't written anything for this

I think you could accept yes or no with the right reasoning, but I imagine that they want you to say it can, because more moles of CO₂ are used than are produced.

also, for 7)c.i i got 800g/mol. if i used that value in 7)c.ii would i get consequential marks?

Yes, you should.

[zoharreznik]

also, for 7)c.i i got 800g/mol. if i used that value in 7)c.ii would i get consequential marks?

I think this is the correct answer. It doesn’t make sense to have a triglyceride with 62 H molecules since you have C16H30O2 * 3 + C3H8O3 - 3 H2O

[fwift52]

I think this is the correct answer. It doesn’t make sense to have a triglyceride with 62 H molecules since you have C16H30O2 * 3 + C3H8O3 - 3 H2O

yeah it should be 800. The answer is wrong there. 92 H not 62

[AR1472]

woah thank you keltingmeith for your explanation!! that would make sense, i never really considered non SLC.

also thanks fwift52 and zoharreznik :PP im so relieved i got that right i spent way too long on it

[jess2002]

What were the 2 different ways to present the results in the short answer question for the effect of temperature on the rate of reaction question?

[AR1472]

What were the 2 different ways to present the results in the short answer question for the effect of temperature on the rate of reaction question?

IV on the x axis and DV on the y axis, as well as drawing a best line of fit (rather than connecting each individual point).

I did the first, but instead of the second i talked about having a better title that actually presents the relationship between the IV and DV, but not sure if that would work

[jess2002]

For the question of why the aqueous solution was unsafe, i wrote water is a stronger oxidant than iodine ion and so would be reduced in preference producing Hydrogen gas. Would this be correct?

[keltingmeith]

For the question of why the aqueous solution was unsafe, i wrote water is a stronger oxidant than iodine ion and so would be reduced in preference producing Hydrogen gas. Would this be correct?

Which question was this?

[jess2002]

Which question was this?

It was the lithium carbon dioxide electrolytic cell question

[keltingmeith]

It was the lithium carbon dioxide electrolytic cell question

Yeah - so, the hydrogen gas one could be something they accept, and the tutoring agency that shared their answers wrote that as well. For me, the first thing I notice is that there's so much lithium around. Lots and lots and lots of lithium, which is an alkali metal. Pretty much any alkali metal + water = highly exothermic reaction, which is the big thing that I'd be cautious of. Presumably - they accept both.