Question

How do you find formula mass of a compound?

Answer 1

Got a Periodic Table....?

Explanation:

Of course you have, you are doing your chemistry homework...

So let us find the formula mass of `CaSO_4`..

The Table tells us that the molar masses of calcium, sulfur, and oxygen, are `40.1*g*mol^-1`, `32.06*g*mol^-1`, and `16.0*g*mol^-1`, respectively. The mole is simply a large number so chosen that `1*mol` of `""^1H` ATOMS, has a mass of `1*g` precisely... Of course, the elemental molar masses are listed on the Periodic Table; you are not required to remember then, tho you will soon commit the masses of the common atoms to memory..

And so we take the sum...

`"Formula mass of calcium sulfate"-={40.10+32.06+4xx16.00}*g*mol^-1=136.16*g*mol^-1`...