## General Chemistry (4th Edition)

1. Calculate the hydronium concentrations when pH = 3.0 and when pH = 5.6. $[H_3O^+] = 10^{-pH}$ $[H_3O^+] = 10^{- 3}$ $[H_3O^+] = 1 \times 10^{- 3}M$ $[H_3O^+] = 10^{-pH}$ $[H_3O^+] = 10^{- 5.6}$ $[H_3O^+] = 2.512 \times 10^{- 6}M$ ** Without significant figures. $[H_3O^+] = 3 \times 10^{-6}M$ ** With significant figures. 2. Now, divide the first number by the second one $\frac{1\times 10^{-3}}{2.512 \times 10^{-6}} = 398$ ** Without significant figures. $\frac{1\times 10^{-3}}{3 \times 10^{-6}} = 300$** With significant figures.