(II) What is the total charge of all the electrons in a 12-kg bar of gold? What is the net charge of the bar? (Gold has 79 electrons per atom and an atomic mass of 197 u.)

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1. Determine the number of moles of gold in the 12-kg bar. Use the atomic mass of gold (197 u) and Avogadro's number (approximately $6.022 \times 10^{23}$ atoms per mole). The formula to calculate the number of moles is: \( \text{moles} = \frac{\text{mass}}{\text{atomic mass}} \).
2. Calculate the total number of gold atoms in the bar by multiplying the number of moles by Avogadro's number.
3. Since each gold atom has 79 electrons, multiply the total number of gold atoms by 79 to find the total number of electrons in the bar.
4. Calculate the total charge of all the electrons. Use the charge of a single electron, which is approximately $-1.602 \times 10^{-19}$ coulombs. Multiply the total number of electrons by the charge of one electron to find the total charge.
5. Assuming the bar is electrically neutral, the net charge of the bar is zero. This is because the positive charges (protons) in the gold atoms balance out the negative charges (electrons).