Calculate the mass and volume of hydrogen and oxygen that is formed during the decomposition of 90 g of water.

Given:
m (H20) = 90 g
To find:
m (H2) -?
V (H2) -?
Decision:
1) 2H2O = 2H2 + O2
Let H2 be x r
2) m1: M1 = m2: M2
3) M1 (H2) = 1 x 2 = 2, since 2 moles = 4 g / mol
M2 (H20) = 1 X 2 + 16 = 18, since 2 moles = 36 g / mol
4) 90 g: 26 g / mol = x: 36 g / mol
x = (90 x 4): 36 = 10g (H2)
5) m: M = V: Vm
V = (m х Vm) / M
6) Vm (H2) = 22.4 X 2 = 44.8 L / mol
Let H2 be x l
7) V (H2) = (90 g x 44.8 L / mol): 36 = 112 L
Answer: m (H2) = 10 g; V (H2) = 112 l