2.Mass Percentage and Decimal Rounding:

Moderators: Chem_Mod, Chem_Admin

MaryBanh_2K
Posts: 101
Joined: Wed Sep 18, 2019 12:21 am

2.Mass Percentage and Decimal Rounding:

Postby MaryBanh_2K » Thu Oct 03, 2019 9:53 pm

When finding the mass percentage, is there a certain decimal we are supposed to round to?

Wilson 2E
Posts: 100
Joined: Sat Aug 17, 2019 12:18 am

Re: 2.Mass Percentage and Decimal Rounding:

Postby Wilson 2E » Thu Oct 03, 2019 9:59 pm

Most elements on the periodic table are typically given to the hundredths place, so it's best to match that when using percentages so the number of sig figs match up.

Kyle Thorin
Posts: 50
Joined: Sat Aug 24, 2019 12:16 am

Re: 2.Mass Percentage and Decimal Rounding:

Postby Kyle Thorin » Thu Oct 03, 2019 10:04 pm

Generally, you're going to want to round to the hundredths so that when you convert to grams you are precise to two decimals, which is usually sufficient for a chemical equation.

charleejohnson1L
Posts: 99
Joined: Fri Aug 30, 2019 12:17 am

Re: 2.Mass Percentage and Decimal Rounding:

Postby charleejohnson1L » Thu Oct 03, 2019 10:06 pm

I've been basing my significant figures off of the molar masses indicated on the periodic table. If there is a given mass in the problem, match your percentages to that amount of sig figs. :)

katrinawong3d
Posts: 40
Joined: Sat Aug 17, 2019 12:17 am

Re: 2.Mass Percentage and Decimal Rounding:

Postby katrinawong3d » Thu Oct 03, 2019 10:07 pm

Agreed with the previous answer, I would match the sig figs and round at the end.

Eunice Nguyen 4I
Posts: 100
Joined: Sat Aug 17, 2019 12:17 am

Re: 2.Mass Percentage and Decimal Rounding:

Postby Eunice Nguyen 4I » Thu Oct 03, 2019 10:10 pm

I typically just match the sig figs to the periodic table values or the numbers given from the question itself. Make sure to never round til the end!!

ClayMeunier1E
Posts: 5
Joined: Fri Aug 09, 2019 12:15 am

Re: 2.Mass Percentage and Decimal Rounding:

Postby ClayMeunier1E » Thu Oct 03, 2019 10:32 pm

Like other people are saying, it's probably best to round to the hundredths place. Personally, however, I like to round to the thousandths place to increase the likelihood that my percentages will add up to 100.

Anna Chen 1K
Posts: 104
Joined: Thu Jul 25, 2019 12:18 am

Re: 2.Mass Percentage and Decimal Rounding:

Postby Anna Chen 1K » Thu Oct 03, 2019 11:28 pm

I would just use the exact values on the periodic table values or the given values, not change the amount of sig figs. I usually only round to the hundredths place, if required, in the end.

Charlene Datu 2E
Posts: 62
Joined: Wed Sep 11, 2019 12:16 am

Re: 2.Mass Percentage and Decimal Rounding:

Postby Charlene Datu 2E » Thu Oct 03, 2019 11:39 pm

When finding my answer, I keep the answer to each step to the thousandths place, but I make sure that my final answer follows sig figs (based off of given).

aishwarya_atmakuri
Posts: 101
Joined: Sat Jul 20, 2019 12:15 am

Re: 2.Mass Percentage and Decimal Rounding:

Postby aishwarya_atmakuri » Thu Oct 03, 2019 11:42 pm

I would use the same number of significant figures as what is given in the problem.

McKenna_4A
Posts: 115
Joined: Sat Aug 24, 2019 12:18 am

Re: 2.Mass Percentage and Decimal Rounding:

Postby McKenna_4A » Fri Oct 04, 2019 1:52 pm

Just remember sig figs based off the problem. Your periodic table may have extras/not enough.


Return to “SI Units, Unit Conversions”

Who is online

Users browsing this forum: No registered users and 1 guest