Ionization constants, ionization of water, pH scale
- Phosphoric acid ionizes in three steps with ionization constant values K_a_1, K_a_2 and K_a_3, respectively, while K is the overall ionization constant. Which of the following statements are true?A. K = K_a_1 + K_a_2 + K_a_3B. H_3PO_4 is a stronger a… Answer: 4. A, B and C only Key idea: overall K=K_(a_1)K_(a_2)K_(a_3) , and each successive ionization is harder. A true: taking logs, log K=... 1
- Following solutions were prepared by mixing different volumes of NaOH and HCl of different concentrations :a. 60 mL M/10 HCl + 40 mL M/10 NaOHb. 55 mL M/10 HCl + 45 mL M/10 NaOHc. 75 mL M/5 HCl + 25 mL M/5 NaOHd. 100 mL M/10 HCl + 100 mL M/10 NaOHpH… Answer: 4. c pH = 1 means [H^+]=0.1 M, so excess strong acid of that concentration must remain after mixing. a: HCl 6 mmol, NaOH 4 mmol, exc... 1
- The percentage of pyridine (C_5H_5N) that forms pyridinium ion (C_5H_5N^+H) in a 0.10 M aqueous pyridine solution (K_b for C_5H_5N = 1.7×10^-9) is Answer: 1. 0.013% Key idea: for a weak base, α=√(K_b/C) . α=sqrtfrac1.7×10⁻⁹0.10=sqrt1.7×10⁻⁸=1.3×10⁻⁴ Percentage = 1.3×10⁻⁴×100=0.013% . 1