By burning hydrogen in oxygen, 72 g of water were obtained. Find the mass of oxygen that has reacted.

univerkov | January 17, 2021 | education

Given:
m (H2O) = 72 g
Find: m (O2)
Decision:
2H2 + O2 = 2H2O
n (H2O) = m / M = 72 g / 18 g / mol = 4 mol
n (H2O): n (O2) = 2: 1
n (O2) = 4 mol / 2 = 2 mol
m (O2) = n * M = 2 mol * 32 g / mol = 64 g
Answer: 64 g

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