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Significant digits in percent error calculation?
I'm not sure when I'd round. Heres the question:
36.08% is the theoretical percent(of water in CuSO4*5H2O)
35.7% was my experimental percent.
1) %error=[ (36.08%-35.7%)÷36.08%]×100%
2)[(0.38)÷36.08%]×100%
3)(0.010532) ×100%
4) 1.0532%
I get the steps, but not sure when to round and use Sig digs.
On step 3), should it be rounded right away to 0.11 (2 Sig digs since 0.38 has 2 Sig digs?)
Or leave it to the end? help!!
1 Answer
- Trevor HLv 77 years agoFavorite Answer
The rule is that you only round for significant figures at the very last step . In fact it is a good idea throughout the problem to have 1 or 2 digits in excess of the required number of significant figures - this is intended to avoid an accumulation of errors from rounding.
The final answer must have 3 significant digits - This is based on the data given : 35.7 has 3 significant digits . It is incorrect to say that the final answer must have 2 significant digits because in the calculation you have a value of 0.38.
Step 4 the calculated value is 1.0532%
Answer - correct to 3 significant digits is 1.05%