Question

Name the law or principle to which the following observations confirm:
(1) When water is added to a $1.0M$ aqueous solution of acetic acid, the number of hydrogen ion $\left(H^{+}\right)$ increases.
(2) When $9650$ coulombs of electricity is passed through a solution of copper sulphate, $3.175g$ of copper is deposited on the cathode (atomic weight of $Cu=63.5$).
(3) When ammonium chloride is added to a solution of ammonium hydroxide, the concentration of hydroxyl ions decreases.

Answer 1

(1) When water is added to a $1.0M$ aqueous solution of acetic acid, the number of hydrogen ion ($H^{+}$) increases.
Ostwald's dilution law: The degree of dissociation of a weak electrolyte is inversely proportional to the square root of it's concentration.
$\alpha =\sqrt{\frac{K}{C}}$
(2) When $9650$ coulombs of electricity is passed through a solution of copper sulphate, $3.175g$ of copper is deposited on the cathode (atomic weight of $Cu=63.5$).
Faraday's first law of electrolysis: The amount of substance that undergoes oxidation or reduction at each electrode during electrolysis is directly proportional to the amount of electricity that passes through the cell.
(3) When ammonium chloride is added to a solution of ammonium hydroxide, the concentration of hydroxyl ions decreases.
Common ion effect: If to the solution of a weak electrolyte, a solution of strong electrolyte is added which furnishes an ion common to that furnished by the weak electrolyte, the ionization of the weak electrolyte is suppressed.
$N{H}_{4}OH\rightleftharpoons N{H}_4^{+}+O{H}^{-}$
$N{H}_{4}Cl\rightleftharpoons N{H}_4^{+}+C{l}^{-}$