Edexcel IGCSE Chemistry January 2016 (18th)

do

do you know why it is initially white smh?

copper sulfate is meant to be a blue salt because of the water formed alongside it when copper hydroxide reacts with sulfuric acid.
cu(oh)2 + h2so4 ----> cuso4 + h2o

but if you heat it, the water of crystallisation disappears which turns it from blue to white.

cus04.5h2o ---> cuso4

Because the water has been removed, it is called anydrous (without water).. but if you add water again it turns from white to blue again.(hydrous or hydrated)
cuso4 + h2o-----> cuso4.5h20

So anhydrous copper sullfare is white and if you add water it becomes hydrated therefore it turns blue

Miheal r u a boy or girl?

copper sulfate is meant to be a blue salt because of the water formed alongside it when copper hydroxide reacts with sulfuric acid.
cu(oh)2 + h2so4 ----> cuso4 + h2o

but if you heat it, the water of crystallisation disappears which turns it from blue to white.

cus04.5h2o ---> cuso4

Because the water has been removed, it is called anydrous (without water).. but if you add water again it turns from white to blue again.(hydrous or hydrated)
cuso4 + h2o-----> cuso4.5h20

So anhydrous copper sullfare is white and if you add water it becomes hydrated therefore it turns blue

Can you do http://qualifications.pearson.com/content/dam/pdf/International%20GCSE/Chemistry/2009/Exam%20materials/4CH0_1C_que_20130114.pdf

Question 7 c please, I don't know what to do after working out the number of moles.

i think you will have to find the relative formula mass of PbCO3 and you'll have to find how many times the rfm goes into the 500g of pbco3.if you multiply that by 207g of lead it should give you the answer

Thanks but what about the molar ratio, isn't it in the ratio 1:2?

Can you do http://qualifications.pearson.com/content/dam/pdf/International%20GCSE/Chemistry/2009/Exam%20materials/4CH0_1C_que_20130114.pdf

Question 7 c please, I don't know what to do after working out the number of moles.

exam is very very very soon but i dont know what to revise. just wasting time. shower and etc. do u guys have any final tip or revision i should do to get an a or a star. really stuck dont know what to study

i know every topic and everything now. but in the exam i somehow make loads of silly mistakes. by the way when exams finished tell us how it went. and the answers u got for each question so we can compare them. also when ur results come let us know. plz i cant wait. i need a star. but silly mistakes all the time letting me down getting me 93 out of120 and 43 out of 60. by the way what do u think the grade boundaries gonna be. i have a feeling that ill be just a few marks away from an a star.

145 for a*

is 145 for an a star guaranteed?

yes!! but i might be wrong

have you done jan 2015? i am about to do it haha.. let's do it together if you haven't done it yet