General Science IBDP Chemistry Uncategorized 8. Acids and Bases HL June 9, 2021 Shveta 0 Comments Acids and Bases, ibdp chemistry 1.The Ka value for an acid is 1.0×10–2. What is the Kb value for its conjugate base?1.0×10–2 1.0×10–6 1.0×10–101.0×10–12 2. Separate 20.0 cm3 solutions of a weak acid and a strong acid of the same concentration are titrated with NaOH solution. Which will be the same for these two titrations? I. Initial pH II. pH at equivalence point III. Volume of NaOH required to reach the equivalence pointI only III only I and II only II and III only3. When the following 1.0 mol dm–3 aqueous solutions are arranged in order of increasing pH, which is the correct order? I. Ammonium chloride II. Ammonium ethanoate III. Sodium ethanoateI, II, IIIII, I, III III, I, II III, II, I 4. An acid-base indicator, HIn, dissociates according to the following equation. HIn(aq) H+(aq) + In–(aq) colour A colour B Which statement about this indicator is correct? I. In a strongly acidic solution colour B would be seen. II. In a neutral solution the concentrations of HIn(aq) and In–(aq) must be equal. III. It is suitable for use in titrations involving weak acids and weak bases.I only II only III only None of the above5. What is the concentration of OH– ions (in mol dm–3) in an aqueous solution in which [H+] = 2.0×10–3 mol dm–3? (Kw = 1.0×10–14 mol2 dm–6)2.0×10–3 4.0×10–6 5.0×10–12 2.0×10–17 6. What is the relationship between Ka and pKa?pKa = –log Ka pKa = pKa = log KapKa = 7. The acid dissociation constant of a weak acid HA has a value of 1.0×10–5 mol dm–3. What is the pH of a 0.10 mol dm–3 aqueous solution of HA?23568. Which mixture would produce a buffer solution when dissolved in 1.0 dm3 of water?0.50 mol of CH3COOH and 0.50 mol of NaOH 0.50 mol of CH3COOH and 0.25 mol of NaOH0.50 mol of CH3COOH and 1.00 mol of NaOH0.50 mol of CH3COOH and 0.25 mol of Ba(OH)2 9. Which compound, when dissolved in aqueous solution, has the highest pH?NaCl Na2CO3 NH4Cl NH4NO3 10. Which values are correct for a solution of NaOH of concentration 0.010 mol dm–3 at 298 K? (Kw = 1.0×10–14 mol2 dm–6 at 298 K)[H+] = 1.0×10–2 mol dm–3 and pH = 2.00 [OH–] = 1.0×10–2 mol dm–3 and pH = 12.00 [H+] = 1.0×10–12 mol dm–3 and pOH = 12.00 [OH– ] = 1.0×10–12 mol dm–3 and pOH = 2.0011. Which solution, of concentration 0.10 mol dm–3, has the highest pH value?HCl(aq) MgCl2(aq) NaCl(aq) AlCl3(aq) 12. Which statement about indicators is always correct?The mid-point of an indicator’s colour change is at pH = 7The pH range is greater for indicators with higher pK4 valuesThe colour red indicates an acidic solutionThe pKa value of the indicator is within its pH range13. Which compound will dissolve in water to give a solution with a pH greater than 7?sodium chloridepotassium carbonate ammonium nitrate lithium sulfate 14. An aqueous solution has a pH of 10. Which concentrations are correct for the ions below? [H+(aq)] mol dm–3 [OH–(aq)] mol dm–3 A. 104 10–10 B. 10–4 10–10 C. 10–10 10–4 D. 10–10 10–4 ABCD15. When the following acids are listed in decreasing order of acid strength (strongest first), what is the correct order? Ka benzoic 6.31×10–5 chloroethanoic 1.38×10–3 ethanoic 1.74×10–5 chloroethanoic > benzoic > ethanoic benzoic > ethanoic > chloroethanoic chloroethanoic > ethanoic > benzoic ethanoic > benzoic > chloroethanoic16. The strengths of organic acids can be compared using Ka and pKa values. Which acid is the strongest? A. Acid A pKa = 6 B. Acid B pKa = 3 C. Acid C Ka = 1×10–5 D. Acid D Ka = 1×10–4 ABCD17. Which is the correct statement about the pH and pOH values of an aqueous solution at 25°C?pH + pOH =14.0 pH + pOH =1.0 ×10–14 pH × pOH =14.0 pH × pOH =1.0 ×10–14 18. Which salt, when dissolved in water to form a 1.0 mol dm–3 solution, produces the lowest pH value?Ammonium chlorideAmmonium ethanoateSodium ethanoateSodium chloride19. Which solution has the lowest pH value?Aluminium sulfate Sodium nitrate Potassium chlorideSodium ethanoate 20. Which neutralization reaction could use phenolphthalein (pKa = 9.3) and not methyl orange (pKa = 3.7) as an indicator?NaOH(aq) and HNO3(aq) NH3(aq) and CH3COOH(aq)NaOH(aq) and CH3COOH(aq) NH3(aq) and HNO3(aq) 21. Water dissociates according to the equation H2O(l) H+(aq) + OH–(aq) ΔH = +56 kJ At 25°C water has a pH of 7. Which of the following occurs when water is heated to 30°C?It remains neutral and its pH decreasesIt becomes acidic and its pH decreasesIt remains neutral and its pH increasesIt becomes acidic and its pH increases22. Which mixture would produce a buffer solution when dissolved in 1.0 dm3 of water?0.30 mol of NH3(aq) and 0.30 mol of HCl(aq) 0.30 mol of NH3(aq) and 0.15 mol of HCl(aq) 0.30 mol of NH3(aq) and 0.60 mol of HCl(aq) 0.30 mol of NH3(aq) and 0.15 mol of H2SO4(aq) 23. The pKa values of four acids are as follows. W 4.87 X 4.82 Y 4.86 Z 4.85 What is the correct order when these acids are arranged in order of increasing acid strength?X, Z, Y, W X, Y, Z, WW, Z, Y, X W, Y, Z, X 24. 10 cm3 of 0.01 mol dm–3 nitric acid (HNO3) is diluted with 90 cm3 of water. What is the pH of the resulting solution?123425. A base of concentration 0.10 mol dm–3 is titrated with 25 cm3 of an acid of concentration 0.10 mol dm–3. Which base-acid pair would have the highest pH at the equivalence point?NaOH(aq) and CH3COOH(aq)NaOH(aq) and HNO3(aq)NH3(aq) and HNO3(aq) NH3(aq) and CH3COOH(aq)26. What is the value of [H+] in a buffer solution in which [CH3COOH] = 2.0 mol dm–3 and [CH3COO–] 1.0 mol dm–3? For CH3COOH, Ka = 1.8×10–5 mol dm–3.6.0×10–3 3.6×10–51.8×10–5 9.1×10–6 27. Which salt forms the most acidic solution when added to water?NaCl MgSO4 Al(NO3)3 KHCO3 28. An acid-base indicator has a pKa value of 4.0. At what pH will this indicator change colour?2.04.0 8.0 12.0 29. Which values are correct for a 0.010 mol dm–3 solution of NaOH(aq) at 298 K? (Kw = 1.0×10–14 mol2 dm–6 at 298 K)[H+] = 1.0×10–12 mol dm–3 and pH = 12.00[OH–] = 1.0×10–12 mol dm–3 and pH = 12.00[H+] = 1.0×10–12 mol dm–3 and pOH = 12.00 [OH–] = 1.0×10–12 mol dm–3 and pOH = 12.00 30. At 25°C, Ka for an acid is 1.0×10–2. What is the value of Kb for its conjugate base?1.0×102 1.0×10–2 1.0×1012 1.0×10–12 31. Which statement about indicators is always correct?The mid-point of the pH range of an indicator is 7The pH range is greater for indicators with higher pKa valuesThe colour red indicates an acidic solutionThe pKa value of the indicator is within its pH range
