## Chemistry: A Molecular Approach (3rd Edition)

Number of electrons needed = $6.25\times10^{18}$ Total mass = $5.6875\times10^{-12}$ kg
Charge on 1 electron = $-1.6\times10^{-19}$ C Required charge = $-1$ C Number of electrons needed = $\frac{-1}{-1.6\times10^{-19}}$ = $6.25\times10^{18}$ Mass of $1$ electron = $9.1\times10^{-31}$ kg Thus, total mass = $6.25\times10^{18} \times 9.1\times10^{-31}$ = $5.6875\times10^{-12}$ kg