Question

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

Answer 1

(i) Mass of one electron = 9.10939 × 10–31 kg

Number of electrons that weigh 9.10939 × 10–31 kg = 1

Number of electrons that will weigh 1 g = (1 × 10–3 kg) = 0.1098 × 1031 x 10 -3

                                                                                      = 0.1098 × 1028

                                                                                                                                     = 1.098 × 1027

(ii) Mass of one electron = 9.10939 × 10–31 kg

Mass of one mole of electron = (6.022 × 1023) × (9.10939 ×10–31 kg) = 5.48 × 10–7 kg

Charge on one electron = 1.6022 × 10–19 coulomb

Charge on one mole of electron = (1.6022 × 10–19 C) X (6.022 × 1023) = 9.65 × 104 C

Answer 2

(i) Mass of one electron = 9.10939 × 10–31 kg

Number of electrons that weigh 9.10939 × 10–31 kg = 1

Number of electrons that will weigh 1 g = (1 × 10–3 kg) = 0.1098 × 1031 x 10 -3

                                                                                     = 0.1098 × 1028

                                                                                                                                    = 1.098 × 1027

(ii) Mass of one electron = 9.10939 × 10–31 kg

Mass of one mole of electron = (6.022 × 1023) × (9.10939 ×10–31 kg) = 5.48 × 10–7 kg

Charge on one electron = 1.6022 × 10–19 coulomb

Charge on one mole of electron = (1.6022 × 10–19 C) X (6.022 × 1023) = 9.65 × 104 C