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# Wtf chem? Watch

1. Hey guys, how is it possible to get 90% in both A2 modules of ocr chem a ? any tips and hints from those who did get very good marks in chem will be appreciated! thanks
2. i know this is a totally random thread, but i cant find one on % error, i have a question where measurements are take;
Mass of crucible/g 14.12g
Mass of crucible+ Ca(NO2)2 .XH20 15.00
Mass of crucible+ CaO residue/g 14.41

error of each measurement is +/- 0.01

i know the general formula; error/ reading X 100
but which reading do i take and do i then X3 or X2 as he's taken more than one reading?
Im so confused and i have an exam on it today, any help is greatly apprciated <3
3. (Original post by zcarter1)
i know this is a totally random thread, but i cant find one on % error, i have a question where measurements are take;
Mass of crucible/g 14.12g
Mass of crucible+ Ca(NO2)2 .XH20 15.00
Mass of crucible+ CaO residue/g 14.41

error of each measurement is +/- 0.01

i know the general formula; error/ reading X 100
but which reading do i take and do i then X3 or X2 as he's taken more than one reading?
Im so confused and i have an exam on it today, any help is greatly apprciated <3
Scientists usually take average for two or three values which are consistently close (whatever that might be to you). that way, you reduce the random errors.
4. (Original post by Craming Revision)
Hey guys, how is it possible to get 90% in both A2 modules of ocr chem a ? any tips and hints from those who did get very good marks in chem will be appreciated! thanks
work hard.....

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