An important method for determining the amount of a particular substance is based on measuring the volume of reactant solution. Suppose substance A in solution reacts with substance B. If you know the volume and concentration of a solution of B that just reacts with substance A in a sample, you can determine the amount of A.
Titration is a procedure for determining the amount of substance A by adding a carefully measured volume of a solution of A with known concentration of B untill the reaction of A and B is just completed. Volumetric analysis is a method of analysis based on titrations.
"Equal volume of equinormal solutions exactly neutralise the other solution having same concentration and volume".
V1 N1 = V2 N2
V1, V2 - Volume of solutions.
N1, N2 - Strength of solutions.
Calculating the volume of reactant solution needed
1. What volume of 6M HCl and 2M HCl should be mixed to get one litre of 3M HCl?
Suppose the volume of 6M HCl required to obtain 1L of 3M HCl = XL
Volume of 2M HCl required = (1-x)L
Applying the molarity equation
M1V1 + + M2V2 = = M3V3
6MHCl+ 2MHCl= 3MHCl
6x+2(1-x) = 3x1
6x+2-2x = 3
4x = 1
x = 0.25L
hence, volume of 6M HCl required = 0.25L
Volume of 2M HCl required = 0.75L
2. How much volume of 10M HCl should be diluted with water to prepare 2.00L of 5M HCl.
N1V1 = N2V2
10N HCl = 5N HCl
10xV1 = 5 x 2.00
V1 = (5 x 2.00 )/ 10
Problems for Practice
1. NiSO4 reacts with Na3PO4 to give a yellow green precipitate of Ni3(PO4)2 and a solution of Na2SO4.
3NiSO4(aq) + 2Na3PO4(aq) Ni3(PO4)2 (s) + 3Na2SO4(aq)
How many mL of 0.375M NiSO4 will react with 45.7 mL of 0.265M Na3PO4?
2. What volume of 0.250M HNO3 reacts with 42.4 mL of 0.150M Na2CO3 in the following reaction?
2HNO3(aq) + Na2CO3(aq) 2NaNO3(aq) + H2O(aq)+CO2(g)
3. A flask contains 53.1 mL of 0.150M Ca(OH)2 solution. How many mL of 0.350M Na2CO3 are required to react completely with Ca(OH)2 in the following reaction.
Na2CO3(aq) + Ca(OH)2(aq) CaCO3(aq) + 2NaOH(aq)