In the reaction N2 + 3H2 gives 2NH3, if 1 mole of nitrogen is mixed with 2 moles of hydrogen, the limiting reactant is
- A. nitrogen, because it has the larger molar mass
- B. neither, because both are used up exactly
- C. hydrogen, because 3 moles would be needed to react with 1 mole of nitrogen
- D. nitrogen, because fewer moles of it are present
Explanation
The equation demands three moles of hydrogen for every mole of nitrogen, so 1 mole of nitrogen would need 3 moles of hydrogen and only 2 are available. Hydrogen therefore runs out first and limits the yield to two thirds of a mole of ammonia. Choosing the reactant present in the smaller number of moles without checking the ratio is the standard mistake.