The point of these problems is to calculate the mass of a specific element in a given compound.

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We’re given 88.07 grams of C4H8S, and the molar mass of sulfur is 32.07 grams/mol.

We know that the % mass composition is found by dividing the molar mass of our target element by the total mass of the compound. In this case, it’s 32.07 grams sulfur/88.07 grams C4H8S.

To get a percentage, we multiply that number x 100%, which yields our answer as 36.37% mass composition.

This is interpreted as 36.37% of C4H8S’s given mass is sulfur.

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