Calculate the percent by mass of water in the hydrated calcium sulfate salt?

Answer 1

Take the mass of the water lost and divide that number by the mass of hydrated calcium sulftate. Then multiply your answer by 100. For example:

To find the amount of water, subtract the mass of the anhydrous sample from the hydated one like this:

Mass of hydrated salt: 21.626

Mass of anhydrous salt: 21.441

21.626 - 21.441 = 0.185 (amount of water)

To find the percentage of water, divide the water mass by the hydrated mass number:

.185/21.626 = 0.00855

Now all you need to do is multiply your answer by 100 to get the percentage:

0.00855(100) = .8554%

To see this last part algebraically, you can say, "what percent of the hydrated salt (21.626) is the mass of water (0.185)?"

This would look like: x%(21.626)=0.185

Answer 2

Well, you didn't give us a compound. So that compounds the question from the start. I will use an example though, magnesium chloride.

Magnesium Chloride, MgCl2

Mass of the element you wish to find the mass percent for

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(Mass of element a x # of atoms present) + (Mass of element b x # of atoms present)

Therefore, 24.305 / (24.305) + (35.45 x 2) = 24.305 / 95.2 = 25.5% Mg by mass