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CraftExam
medium difficulty5 min

Solubility and Factors Affecting It

Solubility is the maximum amount of solute that can dissolve in a given amount of solvent at a particular temperature.

In one line: Solubility is substance-specific and temperature-linked.

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Understand it

Solubility depends on the nature of the solute and solvent and also on temperature. Many solid solutes dissolve more in hot water than in cold water, while gases generally become less soluble as temperature rises.

Example

More sugar dissolves in hot tea than in cold tea, but oxygen is less soluble in warm water than in cold water.

Rule to remember

Rule: solubility must be stated for a fixed solvent amount and a fixed temperature.

See it worked out

Follow the example line by line, then use the same method on new questions.

Worked example

  1. 1If a saturated sugar solution at room temperature is heated gently, more sugar can dissolve.
  2. 2On cooling, some sugar may crystallize out because solubility decreases.

Method you can reuse

  1. 1Identify solute and solvent.
  2. 2Decide whether the solute is solid or gas.
  3. 3Check temperature change.
  4. 4State the solubility trend carefully.

Visual tip

A comparison sketch can show fewer dissolved particles in cold water and more in hot water for a solid solute.

Check yourself

Answer the question in your head before opening the answer.

Try it yourself

Why can more sugar dissolve in hot water than in cold water?

Think first, then show answer
More sugar can dissolve in hot water because higher temperature usually increases the solubility of many solid solutes in water.

Common wrong answer

Writing that temperature has the same effect on all substances.

Why it loses marks: Gases and many solids show different trends.

Don't mix this up

Students often write that heating always increases solubility for every solute, including gases.

Exam tip

Always mention temperature when defining solubility because solubility values change with temperature.

Write it in the exam

Each point is worth about one mark. Write point 1 for a 1-mark question and keep adding points as the marks go up.

How CBSE asks it

Questions ask why heating helps dissolve some solids faster or why gas solubility decreases in warm water.
  1. 1

    Enough for 1 mark

    Solubility is the maximum amount of solute that can dissolve in a given amount of solvent at a particular temperature.

  2. 2

    Add for 2 marks

    Example: More sugar dissolves in hot tea than in cold tea, but oxygen is less soluble in warm water than in cold water.

  3. 3

    Add for 3 marks

    Solubility depends on the nature of the solute and solvent and also on temperature.

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