Question

How many moles of P4 would you need to produce 34 g of PH3?

Answer 1

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