posted by Lucia on .
A copper penny has a mass of of 3gram. The atomic number of copper is 29 and the atomic mass is 63,5gram/mol.what is the total charge of all electrons in the penny?
If a penny were made entirely of copper, it would contain 3/63.5 = 0.04724 moles of copper atoms, which would amount to
0.04724 * 6.02*10^23 = 2.84*10^22 copper atoms. Each atom has 29 electrons. Multiply
29*2.84*10^22*(electron charge) for the final answer, in Coulombs.
Since 1983, pennies in the USA have been made of 97.5% zinc, not copper, to save money. The mass decreased from 3.1 g to 2.5 g. They still cost more than 1 cent to produce.