Consider the equation H2 + O2 gives H2O. What volume of hydrogen gas is required to produce 1 mol of water at standard temperature and pressure?

  • A. 11.2 dm3
  • B. 22.4 dm3
  • C. 10 dm3
  • D. 58 dm3

Explanation

Balanced properly the equation is 2H2 plus O2 giving 2H2O, so one mole of water needs one mole of hydrogen, and one mole of any gas occupies 22.4 dm3 at STP. The figure 11.2 dm3 is half a mole and is the trap for anyone who halves the ratio the wrong way. Molar volume is independent of the identity of the gas, which is Avogadro's law.

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