Question

When an electric current is passed through acidulated, water, 112 mL of hydrogen gas at N.T.P. collects at the cathode in 965 seconds. The current passed, in amperes, is- 

(A) 1.0 

(B) 0.5 

(C) 0.1 

(D) 2.0

Answer 1

Correct Answer is: (A) 1.0 

(A) 22,400 mL of hydrogen at STP(or NTP)=2g

∴ 112 mL of hydrogen at

STP = 2g x mL/22,400mL = 10^-2 g

2F 1 mol

∴ 2H⁺ + 2e^– → H₂

2F 1 mol

= 2 × 96,500 C = 2 g,

2 g hydrogen is deposited by 2 × 96,500 C

∴ 10^–2 g hydrogen will be deposited by = 2 x 96,500 x 10^-2 g / 2g = 965 C

Q = i × t 965 = i × 965 i = 1