Patterns of problems

## Solutions

- Let's decode the best possible approach to tackle questions!
1
Pattern- Types of Solutions
Description
Solutions can be of different types, based on numerous criteria. One of them is the physical state of solute and solvent components.
How to approach
While solving questions related to it you should have a broad classification of solutions in your mind, i.e, gaseous solutions, liquid solutions, and solid solutions. Apart from this, you should also have a fair idea of the examples of these solutions.
Try to solve these questions to get the idea-
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2
Pattern- Expressing Concentration of Solutions
Description
Composition of a solution can be explained by expressing its concentration. There are various parameters and quantities which help us in describing the concentration of the solution quantitatively, such as, mass percentage, volume percentage, mass by volume percentage, parts per million, mole fraction, molarity, and molality.
How to approach
While solving related questions, you should be well aware of all the quantities and their formulae which can be used to estimate the concentration of the solution. Let's practice these questions-
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3
Pattern- Solubility
Description
Solubility of a substance is its maximum amount that can be dissolved in a specified amount of solvent at a specified temperature. There are various factors on which solubility depends. The questions usually revolves around solubility of solid in a liquid or gas in a liquid.
How to approach
Before attempting questions related to solubility, brush up your basics, i.e definition, examples, and factors affecting solubility. Also, revise henry's law and its applications. Let's solve a few problems on solubility to master the concept-
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4
Pattern- Vapour Pressure
Description
Vapour pressure is the pressure exerted by a gas in equilibrium with the solid or liquid phase in a closed container at a given temperature. For an ideal solution, the total vapour pressure is the sum of the pressure exerted by each of the volatile component over the solution phase.
The total vapour pressure can be derived from the general definition of Raoult's law.
According to which,
Vapour pressure of each component of the solution is directly proportional to the mole fraction present in the solution
It can be written as-
How to approach
Questions can be asked on vapour pressure of solutions of non-volatile solids in liquids, or vapour pressure of liquid-liquid solutions. While attempting such questions, you should know the theories behind vapour pressure and Raoult's law and its applications. Let's solve the questions to get the idea-
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5
Pattern- Ideal and Non-ideal Solutions
Description
I am sure you know the difference between the ideal and non-ideal solutions. The story of ideality revolves around Raoult's law. The solutions which obey Raoult's law over the entire range of concentration are known as ideal solutions.
How to approach
Questions are generally asked to identify a given solution as ideal or non-ideal, and to further identify non-ideal solution as positive or negative deviation. Before attempting such questions, carefully observe the conditions given and identify the type of attractive forces between the components of the solution. Solve these questions for more clarity-
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6
Pattern- Colligative Properties
Description
Colligative properties of solutions are properties that depend upon the concentration of solute molecules or ions, but not upon the identity of the solute. These properties include vapour pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure.
How to approach
Numerical based questions can be asked related to the mathematical expression of the colligative properties, such as, vapour pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure. Questions related to determination of molar mass can also be asked. To attempt such questions, you have to revise all the related expressions and practice as many questions as you can.
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7
Pattern- Abnormal Masses and Van't Hoff Factor
Description
The calculated molar mass which is either higher or lower than the expected value is known as abnormal molar mass. This happens when the extent of association or dissociation of the solute particles is not considered in calculating the colligative properties. Vant Hoff introduces an i factor called the Van't Hoff Factor which take into account the extent of dissociation or association.
How to approach
Questions can be asked based on degree of dissociation or ionisation and calculating the colligative properties. To answer such questions, revise the concept of colligative properties, calculations of Van't Hoff factor and you're all set! You can solve these questions for more clarification.
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