Molecular weight of P (Phosphorous) = 30.97g/mol
Hydrogen is just 1 g/mol.
How many moles is 34g of PH3?
Get the weight of PH3 (30.97 + (3X1)) = 33.97g/mol
So 34g/33.97g/mol = 1.0009 moles.
I bet for this problem it's easier to round this to 1.
If you look at just the moles in the equation:
P4(s) + 6 H2(g) → 4 PH3(g)
OR
1 + 6 → 4
If 1 (P4) gives us 4 (PH3), what gives us 1 (PH3)?
1/4 = x/1
solve for x
