Q. When 1 g hydrogen (ECE = 1.044$\times 10^{- 8}\ kg\ C^{- 1})$ forms water, 34 kcal heat is liberated. The minimum voltage required to decompose water is
A) 0.75 V
B) 3 V
C) 1.5 V
D) 4.5 V
Explanation
(c) $q = \frac{m}{z} = \frac{1 \times 10^{- 3}}{1.044 \times 10^{- 8}} = \frac{10^{5}}{1.044}$ C;
Given, $H = 43$ k cal.
$= 34 \times 10^{3} \times 4.2$ J
$H = VIt = Vq$
$\therefore V = \frac{H}{q} = \frac{34 \times 4.2 \times 10^{3}}{10^{5}/1.044}$ = 1.49 V
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.