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, $N_a = 6.02\times 10^{23}\ atoms$.

Charge on electron, $e = 1.6\times 10^{-19}\ C$.

To Find :

The total charge of all the electrons.

Solution :

Moles of copper,

$m = \dfrac{3}{63.5}\ moles\\\\m = 0.047 \ moles$

Number of atoms in 0.047 moles of copper :

$n = 0.047\times 6.02\times 10^{23}\\\\n = 2.83\times 10^{22} \ atoms$

Since, there are 29 electrons on each atoms.

So, total charge is :

$C = 2.83\times 10^{22}\times 29\times 1.6\times 10^{-19}\ C\\\\C = 131312\ C\\\\C = 1.31 \times 10^5\ C$

Hence, this is the required solution.