## Organic Chemistry (8th Edition)

There is 1.50g of NaOH in 50ml aqueous solution. To find the pH: 1) Find the molar mass of NaOH. Molar mass of NaOH (22.99+16+1.01)= 40g 2) Convert the 1.50g NaOH into moles. $\frac{1.50g}{40g}$= 0.0375 mol NaOH. 3) The moles of NaOH is equal to the moles of $OH^{-}$ (NaOH is a strong base so it completely dissociates to give $OH^{-}$. 4) Find the concentration of $OH^{-}$ by using the formula to calculate molarity. Molarity= $\frac{moles}{Liters}$= $\frac{0.0375 mol}{0.50L}$= 0.75 M 5) Find the pOH using -log [$OH^{-}$] = -log [0.75] = 0.125 6) Find pH. pH + pOH = 14 --> pH = 14 - 0.125 = 13.88 Thus, pH of the 50ml aqueous solution which has 1.50g NaOH is 13.88