Question

The mass and charge of one mole of electrons, respectively is:
(A) $54.8 \times {10^{ - 7}}$Kg, $9.65 \times {10^4}$C
(B) $5.48 \times {10^{ - 7}}$Kg, $9.65 \times {10^3}$C
(C) $5.48 \times {10^{ - 7}}$g, $9.65 \times {10^4}$C
(D) $5.48 \times {10^{ - 7}}$Kg, $9.65 \times {10^4}$C

Answer 1

Hint: We know that 1 mole of any substance will have $6.02 \times {10^{23}}$ units (Avogadro number) of that substance. Also the charge of 1 electron is $1.6 \times {10^{ - 19}}$C and the mass of 1 electron is $9.1 \times {10^{ - 31}}$Kg. So, to find the charge and mass of 1 mole of electrons, find the product of the number of electrons present in 1 mole and the mass/charge of 1 electron.

Complete step by step answer:
-Let us start by just writing down the charge and mass of 1 electron.
The charge of 1 electron is $1.6 \times {10^{ - 19}}$C and the mass of 1 electron is $9.1 \times {10^{ - 31}}$Kg.
-We know that 1 mole of any substance has $6.02 \times {10^{23}}$ units (Avogadro number) of that substance. Hence we can say that when we say 1 mole of electrons we are referring to $6.02 \times {10^{23}}$ electrons.
-Now, we will calculate the mass of 1 mole of electrons.
Mass of 1 electron = $9.1 \times {10^{ - 31}}$Kg
Number of electrons in 1 mole = $6.02 \times {10^{23}}$
Therefore the mass of 1 mole of electrons = $9.1 \times {10^{ - 31}} \times 6.02 \times {10^{23}}$Kg
= $5.48 \times {10^{ - 7}}$Kg
Hence the mass of 1 mole electron of electrons is $5.48 \times {10^{ - 7}}$Kg.
-Now, we will calculate the charge of 1 mole electrons.
Charge of 1 electron = $1.6 \times {10^{ - 19}}$C
Number of electrons in 1 mole = $6.02 \times {10^{23}}$
Therefore the charge of 1 mole of electrons = $1.6 \times {10^{ - 19}} \times 6.02 \times {10^{23}}$C
= $9.65 \times {10^4}$C
Hence the charge of 1 mole of electrons will be $9.65 \times {10^4}$C.
So, the correct answer is “Option D”.

Note: We all know that there exist three types of particles which constitute an atom: electron, proton and neutron. A proton has a charge equal in magnitude with the electron but with opposite charge and is equal to = $ + 1.6 \times {10^{ - 19}}$C while the charge of an electron is = $ - 1.6 \times {10^{ - 19}}$C. A neutron is a neutral atom with 0 charge. Remember that this charge is always in units of Coulomb (C) and the mass we take here is in Kg (kilogram).