Question

How many electrons make up a charge of -50.0 μc ? Express your answer using three significant figures?

Answer 1

3.12 × 10¹⁴ electrons

Step-by-step explanation:

1 mole of electrons has a charge of -96465 C (Faraday's constant). The moles of electrons that have a charge of -50.0 μc (-50.0 × 10⁻⁶ C) are:

-50.0 × 10⁻⁶ C × (1 mol e⁻/-96465 C) = 5.18 × 10⁻¹⁰ mol e⁻

1 mol of electrons has 6.02 × 10²³ electrons (Avogadro's number). The number of electrons in 5.18 × 10⁻¹⁰ moles of electrons is:

5.18 × 10⁻¹⁰ mol e⁻ × (6.02 × 10²³ e⁻/ 1 mol e⁻) = 3.12 × 10¹⁴ e⁻

Answer 2

The charge on one mole of electrons = 96485 C = 1 Faraday

so if charge is 96485 C the moles of electrons are 1 = 6.023 X 10^23 electrons

if charge is 1 C the number of electrons = 6.023 X 10^23 / 96485

If charge is 50 micro C the number of electrons

= 6.023 X 10^23 X 50 X 10^-6 / 96485

= 3.12 X 10^14 electrons