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What is Henry's law ? Give… (Class 12 Chemistry 2023, Q19)

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ChemistryCBSE Class 12 · Board exam 2023, set 56/1/1 · 2 marks · Very short answer

CBSE Class 12 Chemistry 2023: question 19

Set in the CBSE Class 12 board exam of 2023, paper 56/1/1, section B, question 19, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q19 · 2 marks · Very short answerSolutions

What is Henry's law ? Give one application of it.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 56/1/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

Think about how the solubility of a gas depends on the pressure above the liquid.

Hint 2

Relate the partial pressure of the gas to its mole fraction in solution through a constant.

Hint 3

For the application, think of fizzy drinks or deep-sea divers.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. Henry's law: At a constant temperature, the partial pressure of a gas in the vapour phase is directly proportional to the mole fraction of that gas in the solution: . Here is the partial pressure of the gas, is its mole fraction in the solution and is Henry's law constant.

    1 mark

  2. Application: Soft-drink and soda-water bottles are sealed under high pressure. This increases the solubility of in the drink. (Another accepted example: scuba divers breathe air diluted with helium to avoid the bends.)

    1 mark

Answer: (partial pressure of a gas ∝ its mole fraction in solution); application: CO₂ dissolved in soft drinks by sealing under high pressure.

Where the marks are

  • Correct statement of Henry's law or the relation with terms explained (1 mark)
  • Any one correct application, e.g. soda bottles sealed under pressure or helium–oxygen mixture for divers (1 mark)

Revise the chapter

  • Chapter: Solutions (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Solutions, one at a time, marked against the answer key and marking points.Back to the full paper2023 board paper, set 56/1/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.