In a reaction
Identify the limiting reagent, if any, in the following reaction mixtures.
(i) 300 atoms of A + 200 molecules of B
(ii) 2 mol A + 3 mol B
(iii) 100 atoms of A + 100 molecules of B
(iv) 5 mol A + 2-5 mol B
(v) 2·5 mol A + 5 mol B
According to the given reaction:
(i) 1 atom of A will react with molecules of B2 = 1
300 atoms of A will react with molecules of B2 = 300
But molecules of B2 actually available = 200
∴ B2 is the limiting reactant.
(ii) 1 mol of A reacts with 1 mol of B
∴ 2 mol of A will react with 2 mol of B.
Hence A is the limiting reactant.
(iii) 100 atoms of A will react with 100 molecules of B. Hence there are no limiting reactants.
(iv) 2·5 mol of B will react with 2·5 mol of A. Hence B is the limiting reagent.
(v) 2·5 mol of A will react with 2·5 mol of B.
Hence A is the limiting reagent.
How are 0.50 mol Na2CO3 and 0·50 M Na2CO3 different?
Molar mass of Na2CO3 = 2 x 23 + 12 + 3 x 16 = 106 g
0.50 mol Na2CO3 means 0.50 x 106g = 53g
0.50M Na2CO3 means 0.50 mol i.e. 0.50 x 106g, i.e. 53 g of Na2CO3 are present in 1 litre of the solution.
Calculate the molarity of a solution of ethanol in water in which the mole fraction of ethanol is 0.040.(assume the density of water to be one).