Water can be separated into its elements according to the following equation by electrolysis. If 20.0 g of water is decomposed by this method, how much oxygen gas is produced? 2H₂O ( ) $\rightarrow$ 2H₂(g) + O₂(g)

Question

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According to the balanced equation, 2 moles of H2O produce 1 mole of O2 gas (since the coefficient of H2O is 2 and the coefficient of O2 is 1). The molar mass of water is 18.015 g/mol, so 20.0 g of water is approximately 1.11 moles (20.0 g / 18.015 g/mol). Therefore, we can expect to produce half as many moles of oxygen gas, or 0.555 moles. The molar mass of O2 is 32.00 g/mol, so 0.555 moles is approximately 17.8 g (0.555 mol x 32.00 g/mol). Therefore, the answer is A) 17.8 g.

Water Can Be Separated into Its Elements According to the Following