When small amount of acid is added to water at 25 °C then the Kw

Correct answer: C. Remain constant

  • A. Increases
  • B. Decreases
  • C. Remain constant
  • D. May increase or decrease

Explanation

The ion product of water (Kw) is a constant at a given temperature, specifically 25 °C in this case. When an acid is added to water, the concentrations of H+ and OH- ions change, but the product of these concentrations, Kw, remains constant. This is because Kw is dependent solely on temperature and not on the presence of acids or bases. Therefore, the correct answer is that Kw remains constant. Options suggesting that Kw increases, decreases, or may vary are incorrect because they do not recognize the temperature-dependent nature of Kw.

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About Acids, Bases and Salts

Acid and base behaviour is explained through the Bronsted-Lowry transfer of protons and the Lewis donation or acceptance of electron pairs. The topic includes pH, pOH, ionisation and water equilibrium, plus salt formation and hydrolysis, where a salt solution may become acidic, basic or neutral.

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