A solution is a homogenous mixture of two or more than two substances whose composition can change within a certain limits. A solution of two substances is called binary solution.
In solution, the component that present in small amount is known as solute and the component present in larger amount known as solvent.
Nine kinds of solution are possible.
(i) Gas in gas. When one gas is mixed with another gas, it is called solution of gas in gas. Example : Air is a mixture of nitrogen and oxygen.
(ii) Liquid in gas. When liquid is mixed with large amount of gas, it is called liquid in gas solution. Example: Moisture (water in air).
(iii) Solid in gas. When small amount of solid particles are dispersed in gas, it is called solution of solid in gas. Example: Smoke.
(iv) Gas in liquid. When gas is dissolved in liquid, it is called gas in liquid solution. Examples: CO2 gas dissolved in water, oxygen dissolved in water.
(v) Liquid in liquid. When a liquid is miscible with another liquid, it forms solution of liquid in liquid. Examples. Ethanol dissolved in water, methanol dissolved in water.
(vi) Solid in liquid. When solid is dissolved in water, the solution is called solid in liquid. Examples: Cane sugar dissolved in water, sodium chloride dissolved in water.
(vii) Gas in solid. When gas is present, the solution is called gas in solid. Example: H2 gas in palladium.
(viii) Liquid in solid. When liquid is present in solid, the homogeneous mixture is called solution of liquid in solid. Example: Amalgam of mercury with sodium.
(ix) Solid in solid. When solid is dissolved in another solid, the homogeneous mixture is called solution of solid in solid. Examples: Alloys are solid in solid solution, copper dissolved in gold.
Calculate the mole fraction of benzene in solution containing 30% by mass in carbon tetrachloride.
Let the total mass of the solution be 100g and mass of benzene be 30 g
therefore mass of tetrachloride= (100-30)g = 70g
Molar mass of benzene,
Calculate (a) molality (b) molarity and (c) mole fraction of KI if the density of 20% (mass/mass) aqueous KI is 1.202 g mL-1.
Molarity (M) is defined as number of moles of solute dissolved in one litre (or one cubic decimetre) of solution.
(a) Mol. mass of
Volume of solution = 4.3 L
(b) Number of moles present in 1000 ml of 0.5M H2SO4= 0.5 mol
therefore number of moles present in 30ml of 0.5M H2SO4=mol =0.015mol
therefore molarity =0.015/0.5L
thus molarity is 0.03M
Molality (m) is defined as the number of moles of the solute per kilogram (kg) of the solvent and is expressed as: