Question

Methanol (CH3OH) is the simplest of the alcohols. It is synthesized by the reaction of hydrogen and carbon monoxide

CO(g)+2H2(g)=CH3OH

If 500 mol of CO and 750 mol of H2 are present, which Is the limiting reactant?

Answer 1

By reacting carbon monoxide and hydrogen the formation of methanol takes place, the reaction is,

CO(g)+2H₂(g)⇔CH₃OH (g)

Based on the given reaction, one mole of methanol is obtained by reacting one mole of carbon monoxide (CO) with the two moles of hydrogen (H₂). It is mentioned in the question that for the reaction 500 mol of carbon monoxide and 750 moles of hydrogen are present.

Therefore for 500 moles of carbon monoxide, there is a requirement of 2 × 500 moles of hydrogen, which is equivalent to 1000 moles of hydrogen (H₂). However, only 750 moles of hydrogen is present. Therefore, the limiting reactant in the given case is H₂. The present moles of H₂ will react with 0.5 × 750 moles of CO = 375 mole of CO

The additional or excess concentration of CO, which is the excess reactant will be, 500-375 = 125 moles.