Question

A total of 1.588 F of electricity ( 1 F=1 mol

−
) was required to electrodeposit all of the Zn and Co from a solution of ZnSO and CoSO
4
​
. The mixture of Zn and Co that was deposited had a mass of 48.29 g. Calculate the masses of ZnSO
4
​
and CoSO
4
​
present in the original solution.

Answer 1

To solve this problem, we can use the concept of Faraday's laws of electrolysis. The mass of a substance deposited during electrolysis is directly proportional to the quantity of electricity passed through the solution. The relationship can be expressed by the equation:

Mass

=

Equivalent weight

×

Faraday’s constant

×

Quantity of electricity

Mass=Equivalent weight×Faraday’s constant×Quantity of electricity

Step-by-step explanation:

Calculate the moles of Zn and Co deposited:

The molar mass of Zn is approximately 65.38 g/mol.

The molar mass of Co is approximately 58.93 g/mol.

Calculate the moles of Zn and Co deposited using their masses.

Use the balanced chemical equation for the electrochemical reaction:

�

�

2

+

+

2

�

−

→

�

�

Zn

2+

+2e

−

→Zn

�

�

2

+

+

2

�

−

→

�

�

Co

2+

+2e

−

→Co

Determine the equivalent weight of Zn and Co based on the balanced equations.

Calculate the moles of electrons:

The quantity of electricity (in Faraday) is given as 1.588 F.

Use Faraday's constant to convert Faraday to moles of electrons.

Use the calculated moles of electrons to find the moles of ZnSO4 and CoSO4:

Since the balanced chemical equations involve the transfer of two moles of electrons per mole of Zn and Co, use the stoichiometry to find the moles of ZnSO4 and CoSO4.

Calculate the masses of ZnSO4 and CoSO4:

Use the moles calculated in step 4 to find the masses of ZnSO4 and CoSO4.

Here are the specific steps in a more organized manner:

a. Calculate moles of Zn and Co deposited.

moles of Zn

=

mass of Zn

molar mass of Zn

moles of Zn=

molar mass of Zn

mass of Zn

​

moles of Co

=

mass of Co

molar mass of Co

moles of Co=

molar mass of Co

mass of Co

​

b. Determine equivalent weights of Zn and Co.

Equivalent weight of Zn

=

molar mass of Zn

�

Equivalent weight of Zn=

n

molar mass of Zn

​

Equivalent weight of Co

=

molar mass of Co

�

Equivalent weight of Co=

n

molar mass of Co

​

where

�

n is the number of moles of electrons transferred in the electrochemical reaction.

c. Calculate moles of electrons.

moles of electrons

=

Quantity of electricity (Faraday)

Faraday’s constant

moles of electrons=

Faraday’s constant

Quantity of electricity (Faraday)

​

d. Use stoichiometry to find moles of ZnSO4 and CoSO4.

moles of ZnSO4

=

2

×

moles of electrons

moles of ZnSO4=2×moles of electrons

moles of CoSO4

=

2

×

moles of electrons

moles of CoSO4=2×moles of electrons

e. Calculate the masses of ZnSO4 and CoSO4.

mass of ZnSO4

=

moles of ZnSO4

×

molar mass of ZnSO4

mass of ZnSO4=moles of ZnSO4×molar mass of ZnSO4

mass of CoSO4

=

moles of CoSO4

×

molar mass of CoSO4

mass of CoSO4=moles of CoSO4×molar mass of CoSO4

Remember to use accurate molar masses for ZnSO4 and CoSO4.

Answer 2

To calculate the masses of ZnSO4 and CoSO4 in the original solution, we need to determine the number of moles of Zn and Co that were deposited. Then, we can use the molar ratios of the electrolytes to calculate the masses. The mass of ZnSO4 is 230.90 g and the mass of CoSO4 is 215.52 g.

Step-by-step explanation:

To calculate the masses of ZnSO4 and CoSO4 in the original solution, we need to first determine the number of moles of Zn and Co that were deposited. Since 1 F (Faraday) corresponds to 1 mol of electrons, we can convert the given amount of electricity (1.588 F) to moles of Zn and Co deposited. We can then use the molar ratios of the electrolytes to determine the masses.

First, let's determine the moles of Zn and Co deposited:

moles of Zn = 1.588 mol

moles of Co = 1.588 mol

Next, we need to find the molar masses of Zn and Co from the periodic table:

molar mass of Zn = 65.38 g/mol

molar mass of Co = 58.93 g/mol

Finally, we can calculate the masses of ZnSO4 and CoSO4:

mass of ZnSO4 = moles of Zn x molar mass of ZnSO4 = 1.588 mol x (65.38 g/mol + 32.07 g/mol + 4*16.00 g/mol) = 230.90 g

mass of CoSO4 = moles of Co x molar mass of CoSO4 = 1.588 mol x (58.93 g/mol + 32.07 g/mol + 4*16.00 g/mol) = 215.52 g