AS Chemistry- helping each other out!

So if you're strong in unit 1 there's no way you're gonna fail! see we're already making progress. I would recommend using this guy:

www.youtube.com/user/NewcastleChemistry to help! He should be able to help you with energetics unit 2. Make notes and once you think you've understood head over to:

www.a-levelchemistry.co.uk and select AQA AS and do some of the energetics exercises! This should help reinforce what you've learned.

For the substance questions, I understand some of them can be pretty trick but use the a-levelchemistry website and try out some questions there tell me how it goes

I have a question about a simple calculation, here's the info I'm given;

A 50.0 cm3 sample of 0.100 moldm-3 sulphuric acid was measured.

0.30 g of magnesium carbonate, MgCO3 was weighed.

A measuring cylinder was filled with exactly 100 cm3 of water and supported upside down in a trough of water.

The two pieces of apparatus were connected by a delivery tube so that any gas produced in the side arm flask would be collected in the measuring cylinder. The apparatus was airtight and no leaks were present.
The rubber bung was removed from the side arm flask. The MgCO3 was added and the bung replaced.


After being asked to write the balanced equation, (H2SO4 (aq) + MgCO3 (s) = MgSO4 (aq) + CO2 (g) + H2O (l) )
I was asked to calculate the number of moles of H2SO4 and MgCO3, I calculated the number of moles of H2SO4 (0.005 mol) and then assumed that this was the same for the number of moles of MgCO3 as they are in a 1:1 ratio as shown by the equation, however I appear to be wrong, the answer was 0.0035 mol.... why don't I use the ratio like normal? is it because I haven't been given the same info about MgCO3? I don't get it... thank you guys

Mol=mass/Mr

Mass of MgCO3 was 0.3grams and you can work out the Mr



(You're right that equal moles reacted but you didn't have equal moles to start with)

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Ahh okay I see, I don't know why I find it such a difficult concept to grasp, but that helps, thank you

I feel bad that you posted the WHOLE question lol!

Hahah well people usually tell me I haven't given enough info so I was playing it safe lol :P

Thought I'd share this online app from RSC's Chemnet Its mainly to help A-Level students understand how to use calculations and how to solve and find answers in a step-by-step method. It really helps since some people lose marks on simple calculations Here's the link

Actually that's true, a lot of students here don't include vital information which makes it very difficult to help

Well you helped me just fine! so could you tell me the key to getting an A in Chemistry? Anything you couldn't have done it without?

Past papers, I do AQA and the questions are often very similar!!

Which of the following ions would be deflected most in a mass spectrometer?

A 35Cl+
B 37Cl+
C 37Cl2+
D (35Cl —37Cl)

Why is it C? I thought the heaviest is deflected the least.
I thought A because it'd be 35-1=34, which is the lightest there, therefore deflected the most?

PRSOM, that's great! Thank you