, Tha Catalyst for Chemistry book is available on
1
Amazon, Flipkart and PW Store.
Solutions
Syllabus
Types of solutions, expression of concentration of solutions of solids in liquids, solubility of gases in liquids, solid
solutions, Raoult's law, colligative properties - relative lowering of vapour pressure, elevation of boiling point,
depression of freezing point, osmotic pressure, determination of molecular masses using colligative properties,
abnormal molecular mass, Van't Hoff factor.
Solutions are homogeneous mixtures of two or more than two components.
Homogeneous mixture means composition and properties are uniform throughout the mixture.
Example : Mixture of sugar in water is a homogeneous system. But mixture of sand in water is not homogeneous.
It is called heterogeneous mixture.
Heterogeneous
Mixture
Sand Water Stir Water + Sand
Homogeneous
Mixture
Salt Water Stir Solution
Solutions
Solvent Solute
Component present in the Component present in the
largest quantity. solution other than solvent.
Decides the physical state
of solution.
, CLASSIFICATION
On the basis of physical states of solute and solvent
Type of Solution Solute Solvent Common Examples
Gas Gas Mixture of oxygen and nitrogen gases
Gaseous solutions Liquid Gas Chloroform mixed with nitrogen gas
Solid Gas Camphor in nitrogen gas
Gas Liquid Oxygen dissolved in water
Liquid solutions Liquid Liquid Ethanol dissolved in water
Solid Liquid Glucose dissolved in water
Gas Solid Solution of hydrogen in palladium
Solid solutions Liquid Solid Amalgam of mercury with sodium
Solid Solid Copper dissolved in gold
CONCENTRATION TERMS
(i) Molarity : Molarity (M) is defined as number of moles of solute dissolved in 1000 ml or 1lt or 1dm3 of solution.
Moles of solute
Molarity = - - - (PYQ)
Vol of solution in lt.
0.5 M KOH solution means: 0.5 moles of KOH dissolved in 1 lt or 1000 ml solution.
(ii) Molality : Molality (m) is defined as the number of moles of solute dissolved in 1kg or 1000 gm of solvent.
Moles of solute
Molality =
Weight of solvent in kg
1.1 molal aq urea solution means: 1.1 moles of urea dissolved in 1 kg or 1000 gm of solvent.
Main advantage of molality over molarity – - - - (PYQ)
Molality does not change with temperature whereas molarity decreases with increase in temperature.
Reason : Volume ∝ Temperature (If Volume of solution ↑ molarity ↓)
Q (1) Calculate the mass of urea (NH2CONH2) required in making 2.5 kg of 0.25 molal aqueous solution.
moles of solute
Sol. molality =
weight of solvent in kg
Let the mass of urea (NH2CONH2) added = x gm.
x
Moles of urea = mol [Molecular wt of urea = 60]
60
Weight of solvent = weight of solution – weight of solute
= (2500 – x) gm.
x
60
Molality ⟹ 0.25 =
(2500 − x )
1000
On solving we get x = 36.95 gm.
2 (To buy the Book) Click Here The Catalyst for Chemistry P
W
1
Amazon, Flipkart and PW Store.
Solutions
Syllabus
Types of solutions, expression of concentration of solutions of solids in liquids, solubility of gases in liquids, solid
solutions, Raoult's law, colligative properties - relative lowering of vapour pressure, elevation of boiling point,
depression of freezing point, osmotic pressure, determination of molecular masses using colligative properties,
abnormal molecular mass, Van't Hoff factor.
Solutions are homogeneous mixtures of two or more than two components.
Homogeneous mixture means composition and properties are uniform throughout the mixture.
Example : Mixture of sugar in water is a homogeneous system. But mixture of sand in water is not homogeneous.
It is called heterogeneous mixture.
Heterogeneous
Mixture
Sand Water Stir Water + Sand
Homogeneous
Mixture
Salt Water Stir Solution
Solutions
Solvent Solute
Component present in the Component present in the
largest quantity. solution other than solvent.
Decides the physical state
of solution.
, CLASSIFICATION
On the basis of physical states of solute and solvent
Type of Solution Solute Solvent Common Examples
Gas Gas Mixture of oxygen and nitrogen gases
Gaseous solutions Liquid Gas Chloroform mixed with nitrogen gas
Solid Gas Camphor in nitrogen gas
Gas Liquid Oxygen dissolved in water
Liquid solutions Liquid Liquid Ethanol dissolved in water
Solid Liquid Glucose dissolved in water
Gas Solid Solution of hydrogen in palladium
Solid solutions Liquid Solid Amalgam of mercury with sodium
Solid Solid Copper dissolved in gold
CONCENTRATION TERMS
(i) Molarity : Molarity (M) is defined as number of moles of solute dissolved in 1000 ml or 1lt or 1dm3 of solution.
Moles of solute
Molarity = - - - (PYQ)
Vol of solution in lt.
0.5 M KOH solution means: 0.5 moles of KOH dissolved in 1 lt or 1000 ml solution.
(ii) Molality : Molality (m) is defined as the number of moles of solute dissolved in 1kg or 1000 gm of solvent.
Moles of solute
Molality =
Weight of solvent in kg
1.1 molal aq urea solution means: 1.1 moles of urea dissolved in 1 kg or 1000 gm of solvent.
Main advantage of molality over molarity – - - - (PYQ)
Molality does not change with temperature whereas molarity decreases with increase in temperature.
Reason : Volume ∝ Temperature (If Volume of solution ↑ molarity ↓)
Q (1) Calculate the mass of urea (NH2CONH2) required in making 2.5 kg of 0.25 molal aqueous solution.
moles of solute
Sol. molality =
weight of solvent in kg
Let the mass of urea (NH2CONH2) added = x gm.
x
Moles of urea = mol [Molecular wt of urea = 60]
60
Weight of solvent = weight of solution – weight of solute
= (2500 – x) gm.
x
60
Molality ⟹ 0.25 =
(2500 − x )
1000
On solving we get x = 36.95 gm.
2 (To buy the Book) Click Here The Catalyst for Chemistry P
W
