A-Level OCR Chemistry B (Salters) 2017

Any idea how to work out the mass of the magnesium though? Which concentration of HCl did you use lower or higher? Please reply! Thanks in advance!

Unless ive got it totally wrong it has to be lower. It asked for the minimum amount that reacted with all 5 concentrations of HCl. So if you used the higher, more magnesium would react with it than the lower concentrations, so you had to use lower. I.e a minimum of x g of Mg would react with the smallest number of moles of HCl, but a larger amount of Mg would react more concentrated solutions Of HCl

Hence you use the minimum amount

I used the lowest conc of acid (0.1) as if you use greater concentrations then some of the Mg would remain unreacted at the lower concs? However, now I think about it, I think it can be read in 2 ways, as it could mean the maximum amount that reacts with the 0.5 conc. who knows, such an unspecific question


Posted from TSR Mobile

Lol! I cannot believe I misread it?!? I was almost certain that the question said maximum?!?!?

Sorry you are right it said maximum amount lol, but because it was the maximum amount for ALL 5 concs, its the same as asking what the minimum amount of Mg is that will react with HCl, and this would be the amount that reacts w/ 0.1 mol.

Ah yh, a very ambiguous question though, not very clear at all. Also what's your prediction for a B in paper 3

Has anyone got the papers in pdf

How is everyone preparing for the final exam on the 20th?