ATAR Notes: Forum
VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: jaydee on June 08, 2012, 02:50:08 pm
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This is more to do with back titration than anything else. usually involving different mole ratios etc. If an answer is meant to be to 4 sig figs for example 0.2562 and the answer that u write is 0.2561. do they still penalise u? or is it considered accurate enough to get full marks?
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Depends on how harsh the examiner is, some give some leeway whilst others require the exact answer. However, if you don't make any rounding errors during your calculation, you should be getting the right answer every time.
In prac exams, I'd take a mark off every time something like that comes up, and then go back and check where I rounded off.
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if redone the calculations 3-4 times and i dont round off at all until the very end. i keep the same numbers on my calculator but its that 0.0001 off for some reason...
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It's possible that the company has rounded off earlier, frustratingly, they make these mistakes too :(
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wait this question isnt a company one though! its the 2011 vcaa redox back titration. its q5 of short answer i got the same answer as vcaa for b part i and ii but for part iii i got 0.004061 mol and 0.6481g. the answer says 0.004062mol and 0.6482g. i even followed the solution on the assessor's report :(
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wait this question isnt a company one though! its the 2011 vcaa redox back titration. its q5 of short answer i got the same answer as vcaa for b part i and ii but for part iii i got 0.004061 mol and 0.6481g. the answer says 0.004062mol and 0.6482g. i even followed the solution on the assessor's report :(
VCAA uses exact answer from previous question in their solutions. But it's better to use unrounded values - you are definitely not penalised for this. I never rounded until the end but I still got full marks in those questions (I got a SoM).
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good to get some peace of mind :)
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So we don't have to round off in the steps before the actual answer to a part, we just keep the answers of the mini-steps unrounded to many decimal places and round off appropriately at the end?
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So we don't have to round off in the steps before the actual answer to a part, we just keep the answers of the mini-steps unrounded to many decimal places and round off appropriately at the end?
You round off answers to part a,b,c etc to correct sig figs on ur exam paper, but leave the accurate data on ur calc and use this data for the remainder of the questions.