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I encountered the following problems:

What is the formula weight of:

a. potassium phosphate

b. iron(III) oxide

c. diphosphorous pentasulfide

I know that the formula for (a) is K2S04. Hence I know there are 2K's 1 S and 4 O's. After obtaining the atomic masses, I sum them all up. The answer is 212.3 amu but I dont get this.

Any help would be appreciated

Thanks!

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# Formula Weights

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