Sig Fig Rules

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Nick Fiorentino 1E
Posts: 102
Joined: Wed Sep 18, 2019 12:16 am

Sig Fig Rules

Postby Nick Fiorentino 1E » Thu Oct 03, 2019 2:39 pm

For sig figs in this class, do we round to two or three decimals? Also, do we use the most precise atomic mass in our calculations (3 decimal places)? I use the most precise atomic mass but sometimes it seems like the answers do not

Marykate Abad 3L
Posts: 51
Joined: Wed Sep 18, 2019 12:19 am

Re: Sig Fig Rules

Postby Marykate Abad 3L » Thu Oct 03, 2019 3:02 pm

You would round to the least amount of sig figs given in the problem. For atomic mass, 3 decimal place is fine.

SajaZidan_1K
Posts: 56
Joined: Wed Sep 18, 2019 12:15 am

Re: Sig Fig Rules

Postby SajaZidan_1K » Thu Oct 03, 2019 3:03 pm

For rounding your answer, I would wait to round until you get your final answer to ensure a more precise answer. Also, for sig figs you should look for the smallest sig fig value given in the problem. For instance, if the problem gave you a value with 5 sig figs and a value with 2 sig figs, your answer should be rounded (if needed) to 2 sig figs.

Kallista McCarty 1C
Posts: 212
Joined: Wed Sep 18, 2019 12:18 am

Re: Sig Fig Rules

Postby Kallista McCarty 1C » Thu Oct 03, 2019 3:03 pm

My TA said they aren't too worried about how many sig figs you use, but not to round unreasonably. For example you will get marked down if you round 1.6541 to 2, but you would be fine to round to 1.654.

philipraj_1F
Posts: 52
Joined: Fri Aug 30, 2019 12:16 am

Re: Sig Fig Rules

Postby philipraj_1F » Thu Oct 03, 2019 3:04 pm

For sig figs in general, you round to the lowest amount of sig figs when multiplying or dividing, and the least number of decimal places when adding or subtracting. This link on his website explains it: https://lavelle.chem.ucla.edu/wp-conten ... OUT_SF.pdf. But the number of decimal points can really be anything depending on the sig figs. In terms of atomic mass, I would say use the most precise value given on the periodic table unless you are given something else in the question.

Clarice Chui 2C
Posts: 101
Joined: Fri Aug 30, 2019 12:16 am

Re: Sig Fig Rules

Postby Clarice Chui 2C » Thu Oct 03, 2019 6:26 pm

A fun way to count sig figs is to picture a map of the United States. Picture one arrow from the Atlantic Ocean pointing towards the US and one arrow from the Pacific Ocean also pointing towards the US. The arrows represent which way you start counting from. If there is a Presence of decimal, then look in the Pacific Ocean and work from left to right (ocean to US) counting from first nonzero digit. If there is an Absence of decimal, then look in the Atlantic Ocean and work from right to left (ocean to country) counting from first nonzero digit.

005321227
Posts: 90
Joined: Sat Sep 07, 2019 12:15 am

Re: Sig Fig Rules

Postby 005321227 » Thu Oct 03, 2019 6:55 pm

With sig figs, use the exact values you calculate until you reach your final answer. Then, round to the same number of sig figs as the values given in the problem. If the value is below five, round down. If the value is five or above, round up to the net nearest integer.

005321227
Posts: 90
Joined: Sat Sep 07, 2019 12:15 am

Re: Sig Fig Rules

Postby 005321227 » Thu Oct 03, 2019 6:56 pm

With sig figs, use the exact values you calculate until you reach your final answer. Then, round to the same number of sig figs as the values given in the problem. If the value is below five, round down. If the value is five or above, round up to the net nearest integer.


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