LIMITING REACTANT - FIRST YEAR CHEMISTRY

Limiting Reactant

Limiting Reactant

     A reactant which is used or consumed earlier due to to its lesser amount and controls the amount of product formed in a chemical reaction is called limiting reactant. 

Examples

(i) If 2 moles of H2 and 2 moles of O2 are allowed to react then only 2 moles H2O is produced. 

2H2 + O2 → 2H2O

Here H2 consumes completely and one mole of O2 is left behind unreacted so H2 is limiting reactant and limits the amount of H2O up to 2 moles.

(ii) If 1 mole of C and 1 mole of O2 are allowed to react then only 1 mole CO2 is produced.

C + O2 →  CO2

Here O2 consumes completely and one mole of C is left behind unreacted so O2 is limiting reactant and limits the amount of CO2 up to 1 mole.

(ii) During burning O2 is in excess and a combustile material (coal, candle, paper etc) is in smaller quantity. Combustile material is fully consumed and controls the amount of product so coal, candle or paper is limiting reactant. 

(iii) If we have 20 slices and 9 kababs, we can only make 9 sandwiches as kababs are limiting reactant. 

Notes Prepared By: Prof. Shahbaz Asghar