Ocr a level chemistry isa

I am retaking my AS quantitative and evaluative ISA this year, and have been told the topics are enthalpy for quant and 'The preparation of an organic liquid' for evaluative. Just wondering if anyone would be able to suggest any key topics to revise, questions to look out for, questions people have remembered in the past on these topics...etc.

Any help would be greatly appreciated guys! really want to get an A this time round!! Thanks :smile:

Reply 1

7834

2

Original post by shaz996

I am retaking my AS quantitative and evaluative ISA this year, and have been told the topics are enthalpy for quant and 'The preparation of an organic liquid' for evaluative. Just wondering if anyone would be able to suggest any key topics to revise, questions to look out for, questions people have remembered in the past on these topics...etc.

Any help would be greatly appreciated guys! really want to get an A this time round!! Thanks :smile:

Hey, I see you had no luck with a reply, but I was wondering if you had done any of them yet, and if possible can you suggest what to look out for?
Thanks x

Reply 2

madmike786

3

yeah the quantitiave is on enthalpy and you have to record masses of your experiment work out mass of Mg used and take temperature of HCL before and after exp and work out temp change. The experiment is adding (part 1) strip of solid Mg to HCL and part 2 is adding solid MgO to HCL. You are required to also work out the mass of solution.
Then you do percentage error, then you have to work out heat given out ( Q= MCΔT) the M will be mass of solution , then you work out the moles of Mg ( mass/molar mass), then you work out enthalpy change of experiment : heat given out/moles. (Q/n).

You repeat this with the next experiment using MgO. Same recording of mass temp ect and same analysis questions on heat given out, moles and enthalpy.

Third part of Quantitative OCR AS ISA is using your enthalpy values from part 1 and part 2 to fill out an enthalpy cycle. They give you the cycle and you just have to fill in the values.

You are then asked to work out enthalpy change of formation of MgO ( JUST FOLLOW ARROWS) .