Looking for classes? Ksquare Career Institute, Bengaluru →
4.5 g of aluminium (at. mass 27 amu) is deposited at cathode from $Al^{3+}$ solution by a certain quantity of electric charge. The volume of hydrogen produced at STP from $H^+$ ions in solution by the same quantity of electric charge will be -
A
44.8 L
B
11.2 L
C
22.4 L
D
5.6 L
Detailed Solution
By Faraday's second law, the same quantity of electricity liberates the same number of equivalents of different substances.
$Al^{3+} + 3e^- \rightarrow Al$, so the equivalent mass of Al $= \dfrac{27}{3} = 9$ g
Equivalents of Al deposited $= \dfrac{4.5}{9} = 0.5$
So the same charge (0.5 F) liberates 0.5 equivalent of hydrogen.
$2H^+ + 2e^- \rightarrow H_2$: 1 mole of $H_2$ = 2 equivalents, so 0.5 equivalent = 0.25 mol of $H_2$.
Volume at STP $= 0.25 \times 22.4 = 5.6$ L
$Al^{3+} + 3e^- \rightarrow Al$, so the equivalent mass of Al $= \dfrac{27}{3} = 9$ g
Equivalents of Al deposited $= \dfrac{4.5}{9} = 0.5$
So the same charge (0.5 F) liberates 0.5 equivalent of hydrogen.
$2H^+ + 2e^- \rightarrow H_2$: 1 mole of $H_2$ = 2 equivalents, so 0.5 equivalent = 0.25 mol of $H_2$.
Volume at STP $= 0.25 \times 22.4 = 5.6$ L