How is percent by mass calculated

Anne Marie Helmenstine, Ph. Chemistry Expert. Helmenstine holds a Ph. She has taught science courses at the high school, college, and graduate levels. Facebook Facebook Twitter Twitter. Updated January 31, Featured Video. Cite this Article Format. Helmenstine, Anne Marie, Ph. Mass Percentage Definition and Example.

Calculating the Concentration of a Chemical Solution. Avogadro's Number Example Chemistry Problem. How to Calculate Mass Percent Composition.

Pure Substance Definition in Chemistry. The Measurement of Concentration Calculator computes the percent concentration based on an amount of solute and an amount of solution.

The three functions are:. Chemists frequently like to express their concentration using terms of percentage. Percentage is parts per hundred. Solids are easier to weigh, while liquids are easier to measure volume. We're gonna end up with grams in the numerator, grams in the denominator, the units will cancel out, and we'll get a pure percentage at the end. So let's see, in the numerator, six times And then in the denominator, I'm just going to do the pure calculation first, and then I'm gonna worry about significant figures.

So in the denominator, we have Did I do that right? If I were just to add up everything, not even think about significant figures. So we can type this into a calculator but we should remind ourselves that our final answer should have no more than four significant figures. Because even down here, if we were just doing this blue calculation here, that should only have four significant figures, it would have gotten us to the hundredths place, and so when we add things together, we should get no more than the hundredths place, but even if we rounded over there for significant figures purposes, we would still have at least four, we'd actually have five significant figures.

So this four significant figures is our significant figures limiting factor. So we just have to calculate this and round to four significant figures.

So this will be, I'll say, approximately equal to 0. And we are done. Up Next. The molecular mass is the sum of the mass contributions of each element. Simply add each mass contribution together to find the total. Step 4: Find the mass percent composition of each element. To find the mass percent composition of an element, divide the mass contribution of the element by the total molecular mass. It is always a good idea to check your work.

This example illustrates the effects of significant figures and rounding errors. This example used two significant figures past the decimal point. This example's answer is within these tolerances. Actively scan device characteristics for identification. Use precise geolocation data. Select personalised content. Create a personalised content profile. Measure ad performance.