Chapter Review: Solutions — Class 12 Chemistry, Part 1 (NCERT)

What You Can Do Now

Tick what you can now do after this chapter.

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After This Chapter, I Can...

Questions From the Whole Chapter

Questions from easy to hard across the chapter.

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Which of the following concentration units is a function of temperature?

Conceptual Understanding

Explain the chapter's key ideas in your own words (textbook questions).

Answer the following conceptual questions from the textbook exercises in your own words.

Conceptual Understanding

What role does molecular interaction play in a solution of alcohol and water? (Ex 1.10)
Why do gases always tend to be less soluble in liquids as the temperature is raised? (Ex 1.11)
What is meant by positive and negative deviations from Raoult's law, and how is the sign of $\Delta_{\text{mix}}H$ related to positive and negative deviations from Raoult's law? (Ex 1.14)

Alcohol and Water Interactions

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Focus on how adding alcohol affects the existing hydrogen bonds in water, and what type of deviation from Raoult's law this causes.

Gas Solubility vs. Temperature

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Focus on the enthalpy of dissolution (exothermic/endothermic) and Le Chatelier's Principle.

Deviations and Mixing Enthalpy

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Focus on comparing solute-solvent vs solute-solute interactions and state whether heat is absorbed or released for each deviation type.

Synthesis Challenge: Colligative Combination

A multi-step colligative-property problem from the textbook exercises.

Follow the steps to solve this two-part colligative properties problem.

Synthesis Challenge (Adaptation of Ex 1.20)

A 5% solution (by mass) of cane sugar ( $C_{12}H_{22}O_{11}$ , molar mass = $342\text{ g mol}^{-1}$ ) in water has a freezing point of 271 K.

Calculate the freezing point of a 5% glucose ( $C_6H_{12}O_6$ , molar mass = $180\text{ g mol}^{-1}$ ) solution in water if the freezing point of pure water is 273.15 K.

Identify Given Information

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List the knowns. Hint: Assume 100 g of solution to find the mass of solute and mass of solvent.

Core Formula

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State the formula for freezing point depression.

Calculate Kf for Water using Sugar Data

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Find the depression ΔTf for sugar, determine its molality, and calculate Kf.

Apply Kf to the Glucose Solution

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Show the calculation for glucose's freezing point depression.

Final Freezing Point of Glucose Solution

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Subtract the glucose ΔTf from the pure water freezing point. Include units.

Reasonableness Check

Why should the freezing point of the glucose solution be lower than the sugar solution?

Synthesis Challenge: Osmotic Pressure with Dissociation

Osmotic pressure incorporating van't Hoff factor.

Solve the problem and provide your reasoning.

Synthesis Challenge: Osmotic Pressure with Dissociation (Ex 1.41)

Determine the osmotic pressure of a solution prepared by dissolving 25 mg of $\text{K}_2\text{SO}_4$ in 2 liters of water at 25 °C, assuming that it is completely dissociated.

Assume molar mass of $\text{K}_2\text{SO}_4$ = $174\text{ g mol}^{-1}$ . Use gas constant $R = 0.0821 \text{ L atm K}^{-1} \text{ mol}^{-1}$ (or state if you use $0.083 \text{ L bar}$ ).

Final Osmotic Pressure

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Provide your final calculated value with appropriate units.

Step-by-Step Calculation

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Show how you converted mass to moles, determined molarity, established the van't Hoff factor, and applied the osmotic pressure formula.

Significance of Dissociation

Briefly note how the calculated pressure compares to what it would be if K2SO4 did not dissociate.