(a) What are non-ideal solution?
(b) What role does the molecular interaction play in deciding the vapour pressure of solutions (i) alcohol and kerosene (ii) Chloroform and acetone.
Answer:
When a solution does not obey Raoult’s law over the entire range of concentration, then it is called non-ideal solution.
(a) Non-ideal solutions are these solutions which
(i) do not follow Raoult’s law.
(ii) ΔHmix ≠ 0.
(iii) ΔVmix ≠ 0.
(iv) The force of attraction between A-A and B-B is not equal to A-B.
(b) In alcohol and acetone, force of attraction is less than alcohol and alcohol molecules as well as acetone and acetone molecule, therefore, vapour pressure increases.
In chlorofom and acetone, force of attraction increases due to intermolecular H-bonding, therefore, vapour pressure decreases.
Answer:
osmotic pressure is proportional to the molarity, C of the solution at a given temperature T. Thus: Π = C R T
Here Π is the osmotic pressure and R is the gas constant.
Π = (n2 /V) R T
Here V is volume of a solution in litres containing n2 moles of solute. If w2 grams of solute, of molar mass, M2 is present in the solution, then n2 = w2 / M2 and we can write,
in a dilute aqueous solution molarity is equal to molality.
c = m when p = 1 and solution is dilute.
The osmotic pressure will increase with an increase in molality of the solution at a given temperature.
Answer:
(i) Hemolysis: The red blood cells are protected from the external environment by a semipermeable membrane. The red blood cells are placed in a hypotonic solution. Because the hypotonic solution is less concentrated than the interior of the cell, water moves into the cell. The cell swells and eventually burst, releasing hemoglobin and other molecules. This process is called hemolysis.
(ii) Crenation: When a bacterial cell is placed in a hypertonic (high concentration) sugar solution, the intracellular water tends to move out of the bacterial cell to be more concentrated solution by osmosis. This causes the cell to shrink and eventually, to stop functioning. This process is called crenation.
Answer:
We observe abnormal molecular masses when the solute is an electrolyte and undergo either into association or dissociation.
One unit of an electrolyte compound separates into two or more particles when it dissolves and colligative properties depends on the number of solute particles.
Each NaCl unit dissociates into two ions-Na+ and CI–. Thus, the colligative properties of a 0.1 m solution of NaCl should be twice as great as those of a 0.1 m solution containing a non-electrolyte, such as glucose or sucrose.