Question

SnO2 + 2H2Sn + 2H2O
If you form 42.5g of H2O from the above reaction, how many moles of H2 were present at
the start of the reaction

Answer 1

Answer: 2.36 moles

Explanation:

Using 1 g/mol for the atomic mass of hydrogen and 16 g/mol for the atomic mass of oxygen, we get that the gram-formula mass of water is 1(2)+16=18 g/mol. Thus, 42.5 grams of water is the same as 2.36 moles.

From the reaction, we know that for every 2 moles of water produced, 2 moles of dihydridotin are consumed. In each mole of dihydridotin, there is 1 mole of hydrogen, meaning that 2 moles of hydrogen are consumed.

Thus, the answer is 2.36 moles.