Question

Calculate the total positive or negative charge on a 3.11 g copper penny

Answer 1

mass of copper penny, m = 3.11 g

atomic mass of copper, M = 63.5 g/mol

so, number of mole = 3.11/63.5 = 0.0489

number of copper atoms = number of mole × Avogadro's number

= 0.0489 × 6.023 × 10²³

= 0.2949 × 10²³

= 2.949 × 10²²

number of electrons/protons present in a copper atom = 29

so, total number of electrons/protons present in 2.949 × 10²² copper atoms = 29 × 2.949 × 10²²

= 85.521 × 10²²

= 8.5521 × 10²³

so, total charge on 2.949 × 10²² copper atoms = 8.5521 × 10²² × 1.6 × 10^-19 C

= 136.8336 × 10³ C

= 1.368336 × 10^5 C ≈ 1.37 × 10^5 C

hence, answer is 1.37 × 10^5 C