## Organic Chemistry (8th Edition)

There is 5.00g of HBr in 100ml aqueous solution. To find the pH: 1) Find the molar mass of HBr. Molar mass of HBr = 80.91g 2) Convert the 5.00g HBr into moles. $\frac{5.00g}{80.91g}$= 0.062 mol HBr. 3) The moles of HBr is equal to the moles of $H_{3}O^{+}$ (HBr is a strong acid so it completely dissociates to give $H_{3}O^{+}$. 4) Find the concentration of $H_{3}O^{+}$ by using the formula to calculate molarity. Molarity= $\frac{moles}{Liters}$= $\frac{0.062}{0.1L}$= 0.62M 5) Find the pH using -log [$H_{3}O^{+}$] = -log [0.62] = 0.21 Thus, pH of the 100ml aqueous solution which has 5.00g HBr is 0.21.