Chemistry Unit 5 IAL (WCH05)

Original post by biochris

I dont remember what the question said exactly... but it was for nucleophilic substitution of OH- by Br-, so the mechanism was either Sn1 or Sn2..
what did you answer?

nothing actually... missed two points there :/ i wrote only that the substitution is nucleophilic

Reply 82

Original post by eepero

it said that 0.0067g was the solubility of c2o4 alone i think

no it was for CaC2O4... ions by themeselves dont have solubility values... ionic compounds do..
"A 1.0-L sample of a saturated calcium oxalate solution, CaC2O4, contains 0.0061-g of the salt at 25°C. Calculate the Ksp for this salt at 25°C. – We must first convert the solubility of calcium oxalate from 0.0061 g/liter to moles per liter."

Reply 83

Sophiathecreator

Original post by eepero

70 for A* i hope... maybe even less. really tricky paper and many questions that you couldnt be prepared for. i mean you had to improvise for many of them and apply the theory...

I get that they're trying to make us think rather than use memorised knowledge but how can we when we've been being taught things in a parrot fashioned manner since day 1?

Reply 84

Sophiathecreator

Original post by airheadbuster

Pretty much. :s-smilie:

We spend months on end learning and understanding our unit 5 syllabus, only to a 1hr 40min test on nothing we've done, feels good.

Reply 85

Original post by Sophiathecreator

I get that they're trying to make us think rather than use memorised knowledge but how can we when we've been being taught things in a parrot fashioned manner since day 1?

Well i do not say that this is wrong... i believe that most of the questions must be easy for someone who has studied hard and only say the last 2 or 3 questions should require a better understanding to distinguish between the prepared students and the better prepared...Well there is also a case with idiots like me doing all these difficult questions right and losing about 10 silly points :/ ffs

(edited 9 years ago)

Reply 86

Original post by biochris

no it was for CaC2O4... ions by themeselves dont have solubility values... ionic compounds do..
"A 1.0-L sample of a saturated calcium oxalate solution, CaC2O4, contains 0.0061-g of the salt at 25°C. Calculate the Ksp for this salt at 25°C. – We must first convert the solubility of calcium oxalate from 0.0061 g/liter to moles per liter."

well i misread it then... -1 point for me haha

Reply 87

Original post by eepero

well i misread it then... -1 point for me haha

Btw did you double any of the inaccuracy values to calculate the %error caused by the equipment?

Reply 88

Original post by biochris

Btw did you double any of the inaccuracy values to calculate the %error caused by the equipment?

no it said that the max error in the reading is this so no doubling

Reply 89

Original post by eepero

no it said that the max error in the reading is this so no doubling

we agree on that :smile:

..

Reply 90

Totally messed up the paper guys..
What did you write about the 3 reasons about the pharmaceutical companies ?

plus on section B
Q23 the formulae was C4H4?

Reply 91

DanielDaniels

14

Why bidentate is more stable?
what did you guys write there?

Original post by biochris

we agree on that :smile:

..

Original post by eepero

no it said that the max error in the reading is this so no doubling

Reply 92

Original post by Relaxedexams

For the E cell values, first one was positive and second was negative?

Posted from TSR Mobile

how did you calculate it?

Reply 93

I still dont get what was the ans to mcq 7 :/
i picked C .. what did you guys do?

Reply 94

Original post by Daniel Atieh

Why bidentate is more stable?
what did you guys write there?

bidentate has a higher enthalpy :redface:

Reply 95

yelyahwisqueen

4

Original post by rockstar101

That paper was the worst chem paper i have ever done!
You could not have studied for half of it.....
I wrote colour at end l
Point was pink.....
Got 70.08% for the limestone ques....
I honestly dont know........grade boundaries better be super low!k
Everyone i know basically wanted to commit suicide after that paper.....i usually get 85/90+ in past papers but this one :frown:

Posted from TSR Mobile

Even literally every single person who took the exam in my school had plans to jump off a cliff too. Even the smartest people (I'm talking people with offers to cambridge). Not a single person found that paper easy

Reply 96

airheadbuster

2

Original post by deathbychem

bidentate has a higher enthalpy :redface:

Greater entropy increase of the system. :tongue:

Reply 97

Original post by deathbychem

bidentate has a higher enthalpy :redface:

i talked about entropy as in the reaction more particles are in the rhs and less in the lhs therefore ds total increases therefore it is more stable

Reply 98