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).

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

Sig Figs

Postby Mitch Mologne 1A » Wed Oct 04, 2017 9:50 am

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

Postby Emma Boyles 1L » Wed Oct 04, 2017 11:50 pm

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

Postby aTirumalai-1I » Wed Oct 04, 2017 11:52 pm

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

Postby Brandon Fujii 1K » Thu Oct 05, 2017 10:44 am

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

Postby Mary Becerra 2D » Thu Oct 05, 2017 1:14 pm

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

Postby AlyssaRivera » Mon Jun 11, 2018 9:26 pm

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

Postby Nandhini_2K » Tue Jun 12, 2018 12:43 am

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

Jacob Samuels 1E
Posts: 30
Joined: Fri Apr 06, 2018 11:05 am

Re: Sig Figs

Postby Jacob Samuels 1E » Tue Jun 12, 2018 2:21 am

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 3J
Posts: 37
Joined: Fri Sep 28, 2018 12:18 am

Re: Sig Figs

Postby Diana Chavez-Carrillo 3J » Wed Oct 03, 2018 7:45 pm

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

Postby 905096106 » Fri Oct 05, 2018 11:30 am

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


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