## Chemistry: The Molecular Science (5th Edition)

$C, F$ and $G$.
1. Since we are comparing the pH value, identify all the solutions in the grid: $C : [OH^-] = 3.0 \times 10^{-5}M$ $F : 0.10M LiOH$ $G: [H_3O^+] = 2.00 \times 10^{-8}M$ $I: 0.010M HClO_4$ 2. Now, calculate the pH for each one: $C$: $pOH = -log[OH^-]$ $pOH = -log( 3 \times 10^{- 5})$ $pOH = 4.523$ $pH + pOH = 14$ $pH + 4.523 = 14$ $pH = 9.477$ $9.477 > 7$; Therefore, this is one of the solutions. $F:$ - $LiOH$ is a strong base, so: $[OH^-] = [LiOH] = 0.10M$ $pOH = -log[OH^-]$ $pOH = -log( 0.1)$ $pOH = 1$ $pH + pOH = 14$ $pH + 1 = 14$ $pH = 13$ $13 > 7$; Therefore this is one of the solutions $G:$ $pH = -log[H_3O^+]$ $pH = -log( 2 \times 10^{- 8})$ $pH = 7.699$ $7.699 > 7$; Therefore, this is one of the solutions. $I:$ $HClO_4$ is a strong acid, so: $[H_3O^+] = [HClO_4] = 0.010M$ $pH = -log[H_3O^+]$ $pH = -log( 0.01)$ $pH = 2$ $2 < 7$; Not valid.