Class 12 chemistry chapter 1 solution pdf notes and topic-wise test question answer.
| Download Class 12 Chemistry Chapter 1 Solution pdf Notes |
| Topic | Test Paper pdf | Answer pdf |
|---|---|---|
| Concentration of solution | Paper -1 | answer pdf |
| Solubility, vapour pressure and Raoult’s Law | Paper -2 | answer pdf |
| Ideal & non-ideal solutions, colligative properties, relative Lowering of vapour pressure | Paper -3 | answer pdf |
| Elevation in boiling point, Depression in freezing point, osmotic pressure | Paper -4 | answer pdf |
| Abnormal molecular mass | Paper -5 | answer pdf |
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Previous Year Question Answers Class 12 Chapter 1 Solution
Q.1- 5g of NaOH are dissolved in 500 ml water. Find the molarity of the solution.(RBSE2023)
Q.2-0·2 L of aqueous solution of a protein contains 1·26 g of the protein. The osmotic pressure of such a solution at 300 K is found to be 2⋅57 ×10−3 bar. Calculate the molar mass of the protein.
( R = 0·083 L bar mol–1 K–1)(RBSE2023)
Q.3 Write definition of Osmosis? (RBSE-20)
Q.4 Calculate the osmotic pressure of 0.01 M solution of urea at 27 °C temperature.
(R = 0.0821 L atm K–1 mol–1) (RBSE-20)
Q.5 The colligative property used for the determination of molar mass of
polymers and proteins is :
(a) Osmotic pressure
(b) Depression in freezing point
(c) Relative lowering in vapour pressure
(d) Elevation is boiling point (CBSE-23)
Q.6 Low concentration of oxygen in the blood and tissues of people living at
high altitude is due to :
(a) high atmospheric pressure
(b) low temperature
(c) low atmospheric pressure
(d) both low temperature and high atmospheric pressure (CBSE-23)
Q.7 What is Henry’s law? Give one application.
Q.8 Differentiate between Ideal solution and Non-ideal solution.
Q.9 30 g of urea is dissolved in 846 g of water. Calculate the vapour pressure of water for this solution if vapour pressure of pure water at 298 K is 23 8 mm Hg.
Some important Terms related to class 12 chemistry chapter 1 solution:-
Concentration of Solution
Solutions are homogeneous mixtures containing two or more components. Generally, the component that is present in larger quantity is called solvent. Solvent determines the physical state of the solution. One or more components present in the solution other than solvent are called solutes.
Solutions containing only two components are called binary solutions. Here each component may be
solid, liquid or in gaseous state. Based on this, solutions are of the following types:
Types of Solution
| Types of Solution | Solute | Solvent | Examples |
| Gas | Solid | Hydrogen in Pd, Pt, Ni etc | |
Solid solutions | Liquid | Solid | Amalgam of mercury with sodium |
| Solid | Solid | Gold ornaments, alloys of metals | |
| Gas | Liquid | Oxygen dissolved in water, soda water | |
| Liquid Solution | Liquid | Liquid | Alcohol dissolved in water, dilute acids and alkalies |
| Solid | Liquid | Salt in water, glucose in water | |
| Gas | Gas | Mixture of O2 and CO2 | |
| Gaseous solutions | Solid | Gas | Chloroform mixed with nitrogen gas, water-vapour in air |
| Liquid | Gas | Oxygen dissolved in water, soda water |
Expressing the concentration
There are various ways to express the concentration of a solution, depending on the context and the properties of the solute and solvent. Here are some common methods:
- Molarity (M): Molarity represents the number of moles of solute per liter of solution. It is expressed as mol/L and is widely used in chemical reactions.
- Mass Percent (% mass): Mass percent is the mass of solute divided by the total mass of the solution, multiplied by 100%. It is often used in industries like food and pharmaceuticals.
- Molality (m): Molality represents the number of moles of solute per kilogram of solvent. It is particularly useful in scenarios where temperature changes can affect the volume of the solvent.
- Volume Percent (% volume): Volume percent is the volume of solute divided by the total volume of the solution, multiplied by 100%. It is commonly used in laboratory settings.
Solubility
Solubility of a substance is its maximum amount that can be dissolved in a specified amount of
solvent. It depends upon the nature of solute and solvent, temperature and pressure.
Solubility of a Solid in a Liquid
It is observed that polar solutes dissolve in polar solvents and non polar solutes in non polar solvents.
In general, a solute dissolves in a solvent if the intermolecular interactions are similar in the two or the
general principle related to solubility is that “like dissolves like”.
Saturated and Unsaturated solutions
A solution in which no more solute can be dissolved at the same temperature and pressure is called a
saturated solution. Here there is a dynamic equilibrium between the dissolved solute and the undissolved
solute. A solution in which more solute can be dissolved at the same temperature is called an unsaturated
solution.
Effect of temperature
The solubility of a solid in a liquid mainly depends on temperature. Since the dissolution of a solid in a
liquid is an equilibrium process, it should follow Le Chateliers Principle. In general, if in a nearly saturated
solution, the dissolution process is endothermic (Δsol H > 0), the solubility should increase with rise in
temperature and if it is exothermic (Δsol H > 0) the solubility should decrease with temperature.
Effect of pressure- Henry,s law
Solubility of gases in liquids is greatly affected by pressure and temperature. The solubility of a gas
increases with increase of pressure.
A quantitative relation between pressure and solubility of a gas in a liquid was first given by Henry,
which is known as Henry’s law. “The law states that at a constant temperature, the solubility of a gas in a
liquid is directly proportional to the pressure of the gas”.
Or, “the partial pressure of the gas in vapour phase (p) is proportional to the mole fraction of the gas
(x) in the solution” and is expressed as:
p = KH x
Here KH is the Henry’s law constant. The value of KH depends on the nature of the gas and
temperature. As the value of KH increases, the solubility of the gas in the liquid decreases.
Applications of Henry’s law
- To increase the solubility of CO2 in soft drinks and soda water, the bottle is sealed under high
pressure. - Scuba divers carry oxygen cylinders to breath under deep sea. At high pressure under water, the
solubility of atmospheric gases in blood increases. When the divers come towards surface, the
pressure gradually decreases. This releases the dissolved gases and leads to the formation of bubbles
of nitrogen in the blood. This blocks capillaries and creates a medical condition known as bends. To
avoid bends the cylinders used by scuba divers are filled with air diluted with helium (11.7% helium,
56.2% nitrogen and 32.1% oxygen). - At high altitudes the partial pressure of oxygen is less than that at the ground level. This leads to low
concentrations of oxygen in the blood and tissues of people living at high altitudes or climbers. Low
blood oxygen causes climbers to become weak and unable to think clearly. This condition is known as
anoxia.
Vapour Pressure of Liquid Solutions
In liquid solutions, the solvent is always a liquid. The solute can be a gas, a liquid or a solid. Generally,
the liquid solvent is volatile. The solute may or may not be volatile. Based on the volatility of solute, the
vapour pressure of the solution is greater or less than that of the solvent.
Vapour Pressure of Liquid-Liquid Solutions – Raoult’s Law
A quantitative relationship between the vapour pressure and mole fraction of solute in a solution was
first given by a French chemist F.M Raoult and it is known as Raoult’s Law. It states that for a solution of
volatile liquids, the partial vapour pressure of each component in the solution is directly proportional to its
mole fraction.
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