2.Mass Percentage and Decimal Rounding:

[MaryBanh_2K]

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

[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.

[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.

[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. :)

[katrinawong3d]

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

[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!!

[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.

[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.

[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).

[aishwarya_atmakuri]

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

[McKenna_4A]

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