Propanoic acid is a weak monoprotic acid, with Ka=1.35×10−5 mol dm−3K_{\text{a}} = 1.35 \times 10^{-5}\text{ mol dm}^{-3}Ka=1.35×10−5 mol dm−3 at 298 K.
What is the concentration, in mol dm−3\text{mol dm}^{-3}mol dm−3, of hydrogen ions in a 1.50 × 10-2 mol dm-3 solution of propanoic acid at 298 K?
2.03×10−72.03 \times 10^{-7}2.03×10−7
4.50×10−44.50 \times 10^{-4}4.50×10−4
9.00×10−49.00 \times 10^{-4}9.00×10−4
3.00×10−23.00 \times 10^{-2}3.00×10−2
