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Explain molarity and molality in short. |
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Answer» Solution :Molarity : Molarity (M) is defined as number of moles of solute dissolved in one litre (or one cubic decimeter) of solution. Molarity `=("Molaes of solute")/("VOLUME of solution in litre")` For example :`0.25 mol L^(-1)` (or 0.25 M) solution of NaOH means that 0.25 mol of NaOH has been dissolved in one litre (or one cubic decimeter). MOLALITY :Molality (m) is defined as the number of moles of the solute per KILOGRAM (kg) of the solvent and is expressed as: Molality `(m)=("Moles of solute")/("Mass oif solvent in kg")` For example :1.00 mol `kg^(-1)` (or 1.00 m) solution of KCl means that 1 mol (74.5 g) of KCl is dissolved in 1 k of water. Each method of expressing concentration of the solutions has it sown merits and demerits. Mass % ppm, mole fraction and molality are independent of temperature, whereas not only molarity but also %w/V, %V/V and normality are temperature. Dependant this is because volume DEPENDS on temperature and the mass does not. |
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