0.0075 mole of calcium trioxocarbonate (IV) is added to 0.015 mole of a solution of hydrochloric acid. The volume of gas evolved at s.t.p is?

[Molar volume of a gas at s.t.p = 22.4 dm3]

  • A 224cm3
  • B 168cm3
  • C 112cm3
  • D 100cm3
jamb 2009chemistry

The correct answer is B. 168cm3

1mole of gas at STP = 22.4dm\(^3\)

0.0075 mole of CaCO3  = xdm\(^3\)

cross multiply;

where 22.4dm\(^3\) = 22400cm\(^3\)

x * 1 = 0.0075 * 22400 → 168cm\(^3\)

 the gas CO2 which evolved was gotten from CaCO3 so we use the number of moles of CaCO3 only

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