Question

relative formula mass of ammonium sulphate? i keep getting 114, but the mark scheme says 132?

Answer 1

the charges of the ions have to balance, if you want to make a proper compound. The ammonium is \[(NH_{4})^{+1}\] and the sulfate is \[(SO_{4})^{-2}\]
one piece of each doesn't add up to zero net charge, it doesn't balance. In order to make it balance, you need to have 2 pieces of ammonium, and only 1 piece of sulfate ion:\[(NH_{4})_{2}SO_{4}\] add up all those pieces, and you should get a formula mass of 132, which is about 17 more than you were getting, because of the second ammonium in the formula

Answer 2

ohhh i see now, thank you very much :)