Question

(35) Calculate the total charge of all the electrons in a copper plate of mass 3.0g,

atomic number z = 29 and atomic mass 63.5g/mol. (Avogadro's no.- 6.02x1023
atoms, e = 1.6x10-1°C)

Answer 1

Given :

A copper plate of mass 3.0g.

Atomic number, z = 29.

Atomic mass, M.M = 63.5 g/mol.

Avogadro's number,
`N_a = 6.02* 10^(23)\ atoms`.

Charge on electron,
`e = 1.6* 10^(-19)\ C`.

To Find :

The total charge of all the electrons.

Solution :

Moles of copper,

`m = (3)/(63.5)\ moles\\\\m = 0.047 \ moles`

Number of atoms in 0.047 moles of copper :

`n = 0.047* 6.02* 10^(23)\\\\n = 2.83* 10^(22) \ atoms`

Since, there are 29 electrons on each atoms.

So, total charge is :

`C = 2.83* 10^(22)* 29* 1.6* 10^(-19)\ C\\\\C = 131312\ C\\\\C = 1.31 * 10^5\ C`

Hence, this is the required solution.