Electrolytic determination of equivalent mass Experimental Data: Mass of metal b

Question

Electrolytic determination of equivalent mass

Experimental Data: Mass of metal before electrolysls Eudiometer volume after 1st electrolysis Eudiometer volume after 2nd. electrolysis43.65 m L Total volume of hydrogen collected Mass of metal after 1stand 2nd electrolysis |14.224g and -19118g Atmospheric Pressure . Temperature of electrolyte solution Vapor Pressure of H2O at above temperature* Obtain this value through an online source. Include in your answer where you obtain the reference from Calculations: Calculate the equivalent mass of your unknown metal. Show your complete work below (anda 9,336 15.15 mL 56.0 TORR 27.1 C the back of this page as needed).

Explanation / Answer

Mass of metal before electrolysis = 19.338 g

Mass of metal after first electrolysis = 19.224g

Mass of metal after second electrolysis = 19.118 g

Mass of metal lost = 19.338 g - 19.118 g = 0.220 g

Eudiometer volume after first electrolysis = 45.45 ml

Eudiometer volume after second electrolysis = 43.05 ml

Total volume of hydrogen collected = 45.45 ml +43.05 ml = 88.50 ml

Atmospheric pressure = 756.0 torr

Temperature of electrolyte = 27.1 ºC

Vapor pressure of H2O at 27.1 ºC = 26.895 torr

P Hydrogen = Atmospheric pressure - Vapor pressure of H2O at 27.1 ºC

                      = 756.0 torr - 26.895 torr = 729.105 torr = 0.959 atm

First we need to calculate the number of moles of hydrogen produced. To do this we use the equation PV = nRT

Or

n = PV / RT

Where

P = 0.959 atm

V = 88.50 ml = 0.0885 L

T = 27.1 ºC = 27.1 +273 = 300.1 K

R = 0.082057 L atm / mol /K

n = (0.959 atm * 0.0885L)/(0.082057 L atm / mol /K*300.1K)

n = 0.003446 = 3.45 x 10^-3 moles

Now calculate number of faradays used

2H+ + 2e- ---> H2

1 mole of H2 requires 2 moles of electrons, i.e. 2 faradays

So the number of faradays used is 2(3.45×10^-3) = 6.90 × 10^-3.

Calculate grams of metal lost per faraday.

Grams of metal lost per faraday = Equivalent mass of unknown metal.

Grams of metal lost per faraday =(Mass of metal lost / the number of faradays used)

= 0.220 / 6.90 ×10^-3 = 31.88

Equivalent mass of unknown metal = 31.88

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