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

- $2.0 \times 10^{-5}$ mol $HBr$; in $1.00L$ = $2.0\times 10^{-5}M$ - $HBr$ is a strong acid, therefore: $[H_3O^+] = [HBr] = 2.0 \times 10^{-5}M$ - Now, use this value to calculate the hydroxide concentration. $[H_3O^+] * [OH^-] = Kw = 10^{-14}$ $2 \times 10^{- 5} * [OH^-] = 10^{-14}$ $[OH^-] = \frac{10^{-14}}{ 2 \times 10^{- 5}}$ $[OH^-] = 5 \times 10^{- 10}M$ The most basic solution is the one with the greatest hydroxide concentration. Since (b) : $[OH^-] = 5 \times 10^{-9}M$, (b) has the greater hydroxide concentration, so, it is the most basic solution.