Question

The following data was obtained for Part B of the lab:

Mass of Cu before electrolysis = 20.5492 g

Mass of Cu after electrolysis = 20.3860 g

Time of electrolysis = 563 sec

Average current = 0.88 Amp

Volume of gas collected = 62.7 mL

Atmospheric pressure (corrected to standard conditions) = 760.4 mmHg

Room temperature = 18.1 °C

Vapour pressure of water at 18.1 °C = 15.6 mmHg

Using this data determine:

Moles of Cu consumed:---------- moles

Moles of H2 produced:------------ moles

Experimental value of Faraday’s constant based on Cu consumed:---------C/mole e-

Experimental value of Avogadro’s number using the charge of one electron (1.602 x 10-19 C):-------

Answer 1

Mass of consumed = 20.5492 - 20.3860 = 0.1632 g

i.e. Moles of Cu consumed = 0.1632 g/(63.546 g.mol^-1) = 0.002568 mol

Volume of gas collected = 62.7 mL = 0.0627 L

i.e. Moles of H₂ produced = (0.0627 L/22.4 L)*1 mol = 0.002799 mol

According to Faraday's laws:

m = (E/F)*i*t

Where E = equivalent weight of Cu = 63.546/2 g/equiv = 31.773 g/equiv

i = 0.88 A

t = 563 s

F = Faraday's constant

Now, 0.1632 g = ((31.773 g/equiv)/F} * 0.88 A * 563 s

i.e. Experimental value of F = 96455.975 C/mole e^-

Therefore, the experimental value of Avagadro's number = (96455.975 C/mole e^-)/(1.602 x 10^-19 C​) = 6.021*10²³/mol