How much water would be formed

How much water would form if 4.8 grams of hydrogen reacted completely with 38.4 grams of oxygen?

Molar mass of H2 = 1x2 = 2 g/mol
Molar mass of O2 = 16x2 = 32 g/mol
Molar mass of H2O = 1x2 + 16 = 18


2H­2 + O2 → 2H2O

No. of moles of H2 added = 4.8/2 = 2.4 mol
No. of moles of O2 added = 38.4/32 = 1.2 mol

Mole ratio H2 : O2 = 2 : 1
If all H2 is reacted, O2 needed = 2.4 x (1/2) = 1.2 mol
Hence, both H2 and O2 are completely reacted.

Mole ratio H2 : H2O = 2 : 2 = 1 : 1
No. of moles of H2 reacted = 2.4 mol
No. of moles of H2O formed = 2.4 mol
Mass of H2O formed = 2.4 x 18 = 43.2 g

Alternative method:
Both H2 and O2 are completely reacted.
By the law of mass conservation, mass of H2O formed
= 4.8 + 38.4
= 43.2 g