## Chemistry (7th Edition)

$mass(g) = 8.867\times 10^{- 3}$
1. Calculate [OH^-]: pH + pOH = 14 10.5 + pOH = 14 pOH = 3.5 $[OH^-] = 10^{-pOH}$ $[OH^-] = 10^{- 3.5}$ $[OH^-] = 3.162 \times 10^{- 4}$ - $CaO(aq) + H_2O(l) \lt -- \gt Ca^{2+}(aq) + 2OH^-(aq)$ 2. Since $CaO$ is a strong base that produces 2 OH for each molecule: $[OH^-] = 2 * [CaO]$ $3.162\times 10^{- 4} = 2 * [CaO]$ $\frac{ 3.162\times 10^{- 4}}{ 2} = [CaO]$ $1.581\times 10^{- 4}M = [CaO]$ 3. Calculate the number of moles: $n(moles) = concentration(M) * volume(L)$ $n(moles) = 1.581\times 10^{- 4} * 1$ $n(moles) = 1.581\times 10^{- 4}$ 4. Find the mass value in grams: 40.08* 1 + 16* 1 = 56.08g/mol $mass(g) = mm(g/mol) * n(moles)$ $mass(g) = 56.08 * 1.581\times 10^{- 4}$ $mass(g) = 8.867\times 10^{- 3}$