Rounding in Hess's Law

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Vista_Farkhondeh_3O
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Joined: Tue Jul 12, 2016 3:00 am

Rounding in Hess's Law

Postby Vista_Farkhondeh_3O » Thu Jan 12, 2017 10:38 pm

Do we round to the nearest whole number when calculating delta H? For example, number 8.55 rounded -15.5kJ to -16.

Jonathan Sarquiz 3F
Posts: 32
Joined: Fri Jul 15, 2016 3:00 am

Re: Rounding in Hess's Law

Postby Jonathan Sarquiz 3F » Thu Jan 12, 2017 10:46 pm

For any calculation, whether it is for delta H or heat or anything else, we only round in our final step of the calculation. What we round to depends on the sig figs of the problem. Remember that when we multiply or divide, our final answer uses the smallest amount of sig figs of the given values in the problem. When we add or subtract, we line up the decimals and our sig figs are determined by the place of the last digit of certainty. (So if we add 12.03 with 2.1, we are only certain to the tenth place, so our final answer is 14.1)


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