Theh total volume of gases produced at STP when 1A current is passsed through acidified water for 20 minutes is-:

Question

a)0.29 L

b)0.28 L

c)0.20 L

d)0.3 L

Answer 1

• Electrode equations:

+ (-) cathode **2H+ + 2 e- ==> H2**or **4H+ + 4e-**==>**2H2** for molar electron comparison
+ (+) anode **4OH- -2e- ==> 2H2O(l) + O2**

• Quantity of electricity in Coulombs = current in A x time in seconds
• Q = I x t = 1 x 20 x 60 = 1200 C, now 1 mole of electrons = 96500 C
• so of electrons = 1200 / 96500 = 0.012435
• it takes 4 ***** of electrons to form 1 mole of oxygen gas
• therefore ***** of oxygen formed = 0.012435 / 4 = 0.0031
• 1 mole of gas = 24000 cm3, therefore volume of gas = 0.0031 x 24000 = 74.4 cm3 of O2
• volume of gas = 0.0744 L of O2