## Sig Figs

Science questions not covered in Chem 14A and 14B. Try to limit questions to chemistry (inorganic chemistry, physical chemistry, organic chemistry, biophysical chemistry, biochemistry, materials science, environmental chemistry).

Mitch Mologne 1A
Posts: 74
Joined: Fri Sep 29, 2017 7:04 am

### Sig Figs

When doing a problem that does not have any number values in the question but uses molar masses that extend to 4 sig figs, should you use the standard 3 sig figs in your answer or 4 sig figs coming from the molar masses?

Emma Boyles 1L
Posts: 19
Joined: Thu Jul 27, 2017 3:00 am

### Re: Sig Figs

Even though the molar masses may have 4 sigfigs, I think you only need 3 sigfigs in your final answer. Hope that helps!

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

### Re: Sig Figs

If no values are specified in the problem, I would use the molar masses and round to 4 sig figs, since the periodic table allows for that precision. AKA whenever possible, it's best to be more precise.

Brandon Fujii 1K
Posts: 51
Joined: Fri Sep 29, 2017 7:04 am

### Re: Sig Figs

In addition, if we have to convert our calculated number of moles into grams, do not round off the number of moles. We only round to our number of significant figures at the very end of the problem. i.e. Say we are limited to 3 sig figs, and we calculated 3.45654 moles of Oxygen gas. We would multiply 3.45654 moles of Oxygen by 16.00 g/mol O2 to get 55.3g O2. DO NOT round the number of moles and multiply 3.46 moles of Oxygen by 16.00 g/mol O2. If we rounded the number of moles we would get 55.4g O2. This is known as round off error.

Mary Becerra 2D
Posts: 53
Joined: Fri Sep 29, 2017 7:06 am

### Re: Sig Figs

Personally, I would try to let the calculator do all the work and then round at the very end, so you get the most accurate answer possible.

AlyssaRivera
Posts: 29
Joined: Fri Apr 06, 2018 11:04 am

### Re: Sig Figs

throughout the problem, how many sig figs should we use when plugging things into our calculator? I've gotten different answers on some problems by rounding things that I plug in

Nandhini_2K
Posts: 60
Joined: Fri Apr 06, 2018 11:03 am

### Re: Sig Figs

I round my final solution to keep my answer most accurate as possible.

Jacob Samuels 1E
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Joined: Fri Apr 06, 2018 11:05 am

### Re: Sig Figs

When in the middle of the problem, you should keep as many decimal places as possible, so that there is no rounding error. I usually keep 3 or 4 more decimals than I will need for my answer, just to be safe.

Diana Chavez-Carrillo 2L
Posts: 122
Joined: Fri Sep 28, 2018 12:18 am

### Re: Sig Figs

How can you check if your sig. figs. are too precise or not rounded off enough?

905096106
Posts: 30
Joined: Fri Oct 05, 2018 12:17 am

### Re: Sig Figs

I would round on your last step because the more you round the more your answer becomes inaccurate.