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2.Mass Percentage and Decimal Rounding:

Posted: Thu Oct 03, 2019 9:53 pm
by MaryBanh_2K
When finding the mass percentage, is there a certain decimal we are supposed to round to?

Re: 2.Mass Percentage and Decimal Rounding:

Posted: Thu Oct 03, 2019 9:59 pm
by Wilson 2E
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.

Re: 2.Mass Percentage and Decimal Rounding:

Posted: Thu Oct 03, 2019 10:04 pm
by Kyle Thorin
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.

Re: 2.Mass Percentage and Decimal Rounding:

Posted: Thu Oct 03, 2019 10:06 pm
by charleejohnson1L
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. :)

Re: 2.Mass Percentage and Decimal Rounding:

Posted: Thu Oct 03, 2019 10:07 pm
by katrinawong3d
Agreed with the previous answer, I would match the sig figs and round at the end.

Re: 2.Mass Percentage and Decimal Rounding:

Posted: Thu Oct 03, 2019 10:10 pm
by Eunice Nguyen 4I
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!!

Re: 2.Mass Percentage and Decimal Rounding:

Posted: Thu Oct 03, 2019 10:32 pm
by ClayMeunier1E
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.

Re: 2.Mass Percentage and Decimal Rounding:

Posted: Thu Oct 03, 2019 11:28 pm
by Anna Chen 1K
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.

Re: 2.Mass Percentage and Decimal Rounding:

Posted: Thu Oct 03, 2019 11:39 pm
by Charlene Datu 2E
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).

Re: 2.Mass Percentage and Decimal Rounding:

Posted: Thu Oct 03, 2019 11:42 pm
by aishwarya_atmakuri
I would use the same number of significant figures as what is given in the problem.

Re: 2.Mass Percentage and Decimal Rounding:

Posted: Fri Oct 04, 2019 1:52 pm
by McKenna_4A
Just remember sig figs based off the problem. Your periodic table may have extras/not enough.