Ccea chemistry A2 unit 1 2016 victims thread

Original post by Mr.bob

Why 12.5 and not 25?

because it was when the titration was half way through

Reply 41

Mr.bob

Original post by CERC

because it was when the titration was half way through

Did it not say in the question that though at the Equivalence point the concentration of the salt was equal to the concentration of acid

Reply 42

No it said when the [salt] is the same as the [acid] then the titration is half complete, it was a 1:1 ratio so when 12.5 cm3 has been added half of the acid was used up and half of the salt had formed. Also I googled the acid in question and it's pKa is 2.5

Reply 43

Mr.bob

Original post by Nathanbh321

I am such a fool how did i misrewd the question like that. The worst thing is i knew about how at half neutralisation(i.e. the tutration is half done) the conc of salt = conc of acid but i put my belief in how i read the question :frown:

Reply 44

I wouldn't worry about it it was only 2 marks and you'd most likely get a method mark for 10^(-pKa)

Reply 45

Got 264.4mg or something for the saponification question

Reply 46

So did I and most others in the class, fairly confident that's right.

Reply 47

Original post by Nathanbh321

So did I and most others in the class, fairly confident that's right.

Yeah some people in my school either got it or forgot to divide by 9 so I am sure this is right

Reply 48

how much revision has everyone done for the next one? ive just done amines and trying to learn arenes at the minute. :colondollar:

was everyone able to do the polymer question? i completely forgot how to do it so left it out?
also, for the question where you had to draw the possible structures for the fat worth three marks, did people say it had or hadnt an asymetric centre? I said it didn't!

Reply 49

Original post by CERC

how much revision has everyone done for the next one? ive just done amines and trying to learn arenes at the minute. :colondollar:

I drew two possible structures and labelled them as either optically active or optically inactive. However I said it was optically active in the question below

Reply 50

For the polymer it was addition polymerisation, the c=c bond opened out. Yeah one isomer was and one wasnt, the one with two adjacent oleic acid molecules was, you did have to remove the Carbon and hydrogens from the formula when doing the residual groups though

Reply 51

hey! can someone explain to me how you get an A* at chemistry.I have a high A from AS and I think I did ok in the practical this year. Im pretty sure that ive messed up A2 unit 1 but if I did exceptionally well in the next test could I still get an A*?

Reply 52

In order to get an A*, you need to have 90% overall at A2. I am thinking the A* boundary for unit 1 will definitely be below 90/120, the scaling will help us all

(edited 7 years ago)

Reply 53

Original post by Binajd

In order to get an A*, you need to have 90% overall at A2. I am thinking the A* boundary for unit 1 will definitely be below 90/120, the scaling will help us all

yes, but if you do really badly in one exam but say brilliantly in the rest, then what then???

sorry, its just i really had my heart set on an A* in chemistry and want to know if there is still a chance :colondollar:

(edited 7 years ago)

Reply 54

Original post by CERC

yes, but if you do really badly in one exam but say brilliantly in the rest, then what then???

If you do really badly as in it would prevent you in getting 270/300 at A2, you won't get an A*. However, if you got a low B but really good A* scores in others to get it above 270/300, you will get an A*

Reply 55

Original post by Binajd

thank you

Reply 56

Original post by Binajd

In order to get an A*, you need to have 90% overall at A2. I am thinking the A* boundary for unit 1 will definitely be below 90/120, the scaling will help us all

No way it'll be that low, far easier than last years. But still difficult so I'd say 98-102 for an A*

Reply 57

Original post by Nathanbh321

No way it'll be that low, far easier than last years. But still difficult so I'd say 98-102 for an A*

last year's A2 or AS?

Reply 58