Chemistry question! help?

Question

What mass, in grams, should be weighed for an experiment that requires 1.62 mol (NH4)2 HPO4?

Answer 1

Calculate the molecular weight of ammonium biphosphate:

N: 2 X 14 = 28

H: 9 X 1 = 9

P: 1 X 31

O: 4 X 16 = 64

mw = 132 g per mole

Now multiply by 1.62 (since you need 1.62 mol of the material) = 213.84 grams

Always check the units of what you need to calculate. They will usually indicate what you need to do to get the answer you want. In this case, multiplying grams by grams/mol = grams

Answer 2

Mass= m

mols= n

relative formula mass= Mr

n=m/mr

Therefore m=nxmr

Mr: (14x2)+(1x8)+1+31+(16x4)= 132

mol: 1.62

m=132x1.62

m=213.84g

I think that's right :/