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### 2.Mass Percentage and Decimal Rounding:

Posted: Thu Oct 03, 2019 9:53 pm
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
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
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
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
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
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
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
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
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
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
Just remember sig figs based off the problem. Your periodic table may have extras/not enough.