Question

(i) Calculate the number of electrons which will together weigh one gram.
(ii) Calculate the mass and charge of one mole of electrons.

Answer 1

(i) Mass of one electron = 9.10939 × 10³¹ kg
∴ Number of electrons that weigh 9.10939 × 10³¹ kg = 1
Number of electrons that will weigh 1 g = (1 × 10³ kg)
= \(\frac{1}{9.10039}\) × 10^-31 kg × (1 × 10^-3 kg)
= 0.1098 × 10³ + 31
= 0.1098 × 10²⁸
= 1.098 × 10²⁷
(ii) Mass of one electron = 9.10939 × 10³¹ kg Mass of one mole of electron
= (6.022 × 10²³) × (9.10939 ×10³¹ kg)
= 5.48 × 10⁷kg
Charge on one electron = 1.6022 × 10¹⁹ coulomb
Charge on one mole of electron = (1.6022 × 10¹⁹ C) (6.022 × 10²³)
= 9.65×10 ⁴C