Question

(a) Calculate the number of electrons which will together weigh one gram.

(b) Calculate the mass and charge of one mole of electrons.

Answer 1

(a) Mass of one electron = $9.10939\times {10}^{–31}$ kg
$\therefore$ Number of electrons that weigh $9.10939\times {10}^{–31}$ kg = 1
$\therefore$ Number of electrons that will weigh 1 g (1 × ${10}^{–3}$ kg) $=\frac{1}{9.10939\times {10}^{-31}kg}\times (1\times {10}^{-31}kg)=0.1098\times {10}^{-3+31}=0.1098\times {10}^{28}Numberofelectronswhichwillweigh1gram=1.098\times {10}^{27}$

(b) Mass of one electron = $9.10939\times {10}^{–31}$ kg
Mass of one mole of electron = $6.022\times {10}^{23}\times 9.10939\times {10}^{–31}$ kg = $5.48\times {10}^{–7}$ kg
(c) Charge on one electron = $1.6022\times {10}^{–19}$ coulomb
Charge on one mole of electron = $1.6022\times {10}^{–19}$ C 6.022×10236.022 \times 10^{23} 6.022×1023 = 9.65×104 9.65 \times 10^{4 } 9.65×104C