## Example 8.8

aTirumalai-1I
Posts: 55
Joined: Thu Jul 27, 2017 3:00 am
Been upvoted: 1 time

### Example 8.8

For example 8.8 in the textbook, can someone explain why the answer has 4 significant figures? Since the temperature we use (298 K) has the least number of significant figures (3), shouldn't the answer have 3 sig figs as well?

Vivian Nguyen
Posts: 66
Joined: Fri Sep 29, 2017 7:04 am
Been upvoted: 2 times

### Re: Example 8.8

I believe the answer has "4" significant figures because in the last step, the two values are being added to each other. To do significant figures when you're adding, it depends on how many values are after/before the decimal point.

From the worksheet on Dr.Lavelle's website: "Number of decimal places in answer = Smallest number of decimal places in the initial data"

So in this case -2559 + 14.9 = -2544 because the smallest number of decimals is the ones place.

Hopefully this is right!

Return to “Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)”

### Who is online

Users browsing this forum: Google [Bot] and 3 guests