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AS Chemistry- helping each other out!

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hi does anyone know how to answer these two questions...
Induim has two peaks m/z-113 and m/z-115 and relative atomic mass of this sample is 114.5
calculate the ratio of the relative abundances of the two isotopes and the answer is 1:3 but I don't know how they got to the answer

and another completely different question is..
the relative formula mass is 138.2 of M2CO3
determine the relative atomic mass and deduce the identity of M and the answer is K and 39.1 but I don't know how they got to the answer
please help me btw this is an aqa as chemistry questions thanks in advance

Reply 2641

hannah4262

Hi, anyone doing OCR Chemistry do we need to know about the models of the atom that changed overtime? Thanks :smile:

Reply 2642

Rstlss

Original post by Shadowfire123

hi who here does edexcel for As chemistry>?

Reply 2643

hannah4262

Also does anyone have access to the OCR F321 June 2014 mark scheme? I've got the paper but don't have the mark scheme and I've just realised they haven't been realised yet :frown:

Reply 2644

Loyota

Original post by hannah4262

Hi, anyone doing OCR Chemistry do we need to know about the models of the atom that changed overtime? Thanks :smile:

Salters?

Reply 2645

hannah4262

Original post by Nidfeo

Salters?

No F321?

Reply 2646

C0balt

Original post by cilla_e

Thank you so much!! :smile:

just wondering, are you a genius?

Reply 2647

Shadowfire123

Original post by Rstlss

haha good hows revision going for you then

Reply 2648

nishofficial

How do you work out how many structural isomers an organic compound has? Do you just have to draw it in as many ways as you can? A question asked how many structural isomers does the alkane C5H12 have.

Reply 2649

Rstlss

Original post by Shadowfire123

haha good hows revision going for you then

Not too good, I'd really like an A, but tbh I'd be lucky with a B

Reply 2650

nishofficial

I do edexcel too homies. They're making the papers really hard now

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Reply 2651

cilla_e

In the production of sulphuric acid sulphur dioxide is converted to sulphur trioxide byreaction with the oxygen in the air. What volume of air (assume 20% of the air is oxygen)would be needed to produce 150 cm3 of sulphur trioxide? Assume complete conversion ofsulphur dioxide to sulphur trioxide.

Reply 2652

cilla_e

In the production of sulphuric acid sulphur dioxide is converted to sulphur trioxide by reaction with the oxygen in the air. What volume of air (assume 20% of the air is oxygen) would be needed to produce 150 cm3 of sulphur trioxide? Assume complete conversion of sulphur dioxide to sulphur trioxide.