A sample of butanoic acid, CH3(CH2)2COOH, is shaken with a mixture of two immiscible solvents, ethoxyethane and water. The solvents form two layers. The butanoic acid is distributed between the two layers, its concentration in ethoxyethane being higher than its concentration in water. State what is meant by partition coefficient. [1]

1. (a)(i)A sample of butanoic acid, CH3(CH2)2COOH, is shaken with a mixture of two immiscible solvents, ethoxyethane and water. The solvents form two layers. The butanoic acid is distributed between the two layers, its concentration in ethoxyethane being higher than its concentration in water. State what is meant by partition coefficient. [1][1]
2. (a)(ii)The partition coefficient, Kpc, for butanoic acid between ethoxyethane and water is 3.50. A solution of 2.00g of butanoic acid in 100 cm³ ethoxyethane is added to water. This mixture is left until there is no further change in the concentration of butanoic acid in either solvent. The mass of butanoic acid dissolved in the ethoxyethane layer is now 1.62g. Calculate the volume of water used. volume of water used = ...................................... cm³ [2][2]
3. (b)(i)An aqueous solution of butanoic acid can be used to make a buffer solution. Define buffer solution. [1][1]
4. (b)(ii)Suggest one organic compound, and one inorganic compound, that can be added to two different samples of aqueous butanoic acid to produce buffer solutions. organic compound inorganic compound [1][1]
5. (c)(i)The solubility of aluminium hydroxide, Al(OH)3, in water is 2.47 × 10-9 mol dm-3. Give the expression for the solubility product, Ksp, of aluminium hydroxide. Ksp = [1][1]
6. (c)(ii)Calculate the numerical value of the Ksp of aluminium hydroxide. Include the units of Ksp in your answer. Ksp = units = [3][3]