DP Chemistry Questionbank

• Syllabus

Topic 18: Acids and bases

Sub sections and their related questions

18.1 Lewis acids and bases

• 15M.1.hl.TZ1.8: Which statements are correct about the complex...
• 15M.1.hl.TZ1.28: An equal amount of each of the following salts is added separately to the same volume of...
• 15M.1.hl.TZ2.28: Which compound forms an acidic solution when dissolved in water? A.    ...
• 15M.2.hl.TZ2.7e.i: Define the term base according to the Lewis theory.
• 15M.2.hl.TZ2.8c.ii: Chromium forms the complex ion...
• 15M.1.sl.TZ2.21: Which species cannot function as a Lewis acid? A.     \({\text{B}}{{\text{F}}_{\text{3}}}\) B....
• 15M.2.sl.TZ1.6e: Explain whether BF3 can act as a Brønsted-Lowry acid, a Lewis acid or both.
• 15M.2.sl.TZ2.5f.i: Define the term base according to the Lewis theory.
• 14M.1.hl.TZ1.24: In which reaction does \({{\text{H}}_{\text{2}}}{\text{O}}\) act as a Lewis base but not as a...
• 14M.2.hl.TZ1.5d.ii: \({\text{C}}{{\text{r}}^{3 + }}\) ions and water molecules bond together to form the complex ion...
• 14M.2.hl.TZ1.5d.iv: Outline, including a relevant equation, whether the...
• 14M.3.hl.TZ1.24a: Explain why ethylamine has basic properties.
• 14M.1.sl.TZ2.22: Which statement explains why ammonia, \({\text{N}}{{\text{H}}_{\text{3}}}\), is classified as a...
• 14M.2.sl.TZ2.2d: (i)     State the formula of the compound that boron forms with fluorine.   (ii)     Explain...
• 14M.3.sl.TZ1.24a: State the equation for the reaction of ethylamine with water.
• 14M.3.sl.TZ1.24b: Explain why ethylamine has basic properties.
• 14N.1.hl.TZ0.8: Cobalt forms the complex...
• 14N.1.hl.TZ0.24: Which definition of a base is correct? A.     A Lewis base accepts a proton. B.     A...
• 14N.1.sl.TZ0.21: Which definition of a base is correct? A.     A Lewis base accepts a proton. B.     A...
• 13N.2.hl.TZ0.7b.i: Describe the relationship between \({\text{Sb}}{{\text{F}}_{\text{5}}}\) and...
• 13M.2.hl.TZ1.6d.i: Define an acid according to the Lewis theory.
• 13M.2.hl.TZ1.6d.ii: State and explain the acid–base character of \({\text{PC}}{{\text{l}}_{\text{3}}}\) according to...
• 13M.1.hl.TZ2.26: Which of the following is an example of a Lewis acid–base reaction, but not a Brønsted–Lowry...
• 13M.2.hl.TZ2.6b.i: Define an acid according to the Brønsted–Lowry theory and the Lewis theory.   Brønsted–Lowry...
• 12N.1.sl.TZ0.21: Which substance can act as a Lewis acid but not as a Brønsted–Lowry acid? A.     HCl B.    ...
• 10N.2.hl.TZ0.3f: \({\text{C}}{{\text{u}}^{2 + }}{\text{(aq)}}\) reacts with ammonia to form the complex ion...
• 09M.1.sl.TZ2.21: Which are definitions of an acid according to the Brønsted-Lowry and Lewis theories?
• 11M.2.hl.TZ2.5a.iii: Another weak base is nitrogen trifluoride, \({\text{N}}{{\text{F}}_{\text{3}}}\). Explain how...
• 12M.1.hl.TZ2.23: Which reaction represents an acid–base reaction according to the Lewis theory but not according...
• 12M.2.sl.TZ2.6b.iii: Explain why ammonia can also act as a Lewis base.
• 11N.1.sl.TZ0.21: Which descriptions are correct for both a Brønsted–Lowry acid and a Lewis acid?
• 16M.1.hl.TZ0.28: The diagram represents the bonding in...
• 16M.2.hl.TZ0.1a: (i) Draw a Lewis (electron dot) structure of phosphine. (ii) State the hybridization of the...
• 17M.2.hl.TZ1.2e: Describe, in terms of the electrons involved, how the bond between a ligand and a central metal...
• 17M.1.hl.TZ2.26: Which type of bond is formed when a Lewis acid reacts with a Lewis base? A.     Covalent B.    ...
• 17N.2.hl.TZ0.3e: Describe, in terms of acid-base theories, the type of reaction that takes place between the...
• 18M.1.hl.TZ1.26: Which statements are correct?         I. Lewis bases can act as nucleophiles.         II....
• 18M.2.hl.TZ1.5c: Write an equation to show ammonia, NH3, acting as a Brønsted–Lowry base and a different equation...
• 18M.1.hl.TZ2.26: Which is an example of a Lewis base? A.     an electrophile B.     BF3 C.     CH4 D.     a...

18.2 Calculations involving acids and bases

• 15M.1.hl.TZ1.26: The forward reaction of this equilibrium is...
• 15M.1.hl.TZ1.27: Which equation represents a reaction for which a base dissociation constant expression,...
• 15M.1.hl.TZ2.26: The strengths of four acids are:      glycine     \({\text{p}}{K_{\text{a}}} =...
• 15M.2.hl.TZ1.8b: Calculate the pH, using table 15 of the data booklet, of a solution of ethanoic acid made by...
• 14M.1.hl.TZ1.26: The \({\text{p}}{K_{\text{b}}}\) of \({\text{H}}{{\text{S}}^ - }\) is 7.08. What is its conjugate...
• 14M.1.hl.TZ2.29: What is the expression for the ionic product constant of water, \({K_{\text{w}}}\)? A.    ...
• 14M.2.hl.TZ1.7c.iv: A \({\text{1.50 mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\) solution of ammonia is added to...
• 14M.2.hl.TZ1.7c.v: Calculate the pH of the solution at the equivalence point, using Table 15 of the Data Booklet.
• 14M.2.hl.TZ2.6e.ii: Sulfur dioxide, a major cause of acid rain, is quite soluble in water and the equilibrium shown...
• 14M.3.hl.TZ1.24b: The \({\text{p}}{K_{\text{b}}}\) values at 298 K for diethylamine and triethylamine are given in...
• 14N.1.hl.TZ0.26: Which compound will produce an aqueous solution which has a pH greater than 7? A.    ...
• 14N.1.hl.TZ0.27: Methylamine acts as a weak base when it reacts with water. For a diluted aqueous solution, what...
• 14N.2.hl.TZ0.1d: Determine the concentration of hydroxide ions in the sample of river water.
• 14N.2.hl.TZ0.4c: Phosphoric(V) acid, \({{\text{H}}_{\text{3}}}{\text{P}}{{\text{O}}_{\text{4}}}\), has a...
• 14N.2.hl.TZ0.10e: (i)     State a chemical equation for the partial dissociation of water into ions, including...
• 13N.1.hl.TZ0.28: The table below shows data for the \({{K_{\text{a}}}}\) and \({{\text{p}}{K_{\text{b}}}}\) values...
• 13N.2.hl.TZ0.7e.ii: Francisco and Shamiso found that the pH of the initial...
• 13M.1.hl.TZ1.26: The values of \({K_{\text{w}}}\), the ionic product constant of water, are: Which statements...
• 13M.1.hl.TZ1.27: For which equilibrium can an expression for a base dissociation constant, \({K_{\text{b}}}\), for...
• 13M.1.hl.TZ2.28: The \({\text{p}}{K_{\text{b}}}\) value of ammonia is 4.75 at 298 K. What is the...
• 13M.1.hl.TZ2.29: The \({K_{\text{a}}}\) values of four weak acids W, X, Y and Z are listed below. W    ...
• 13M.2.hl.TZ2.6a: Ammonia, NH3, can be used to clean ovens. The concentration of hydroxide ions, OH–(aq), in a...
• 13M.2.hl.TZ2.6d.iii: \({\text{150 c}}{{\text{m}}^{\text{3}}}\) of...
• 10N.2.hl.TZ0.6b: (i)     Distinguish between the terms strong and weak acid and state the equations used to show...
• 09N.2.hl.TZ0.8a.iii: Calculate the concentration of the weak acid before the addition of any NaOH(aq).
• 09N.2.hl.TZ0.8e.i: Determine the pH of the solution.
• 09N.2.hl.TZ0.8e.ii: Calculate the base dissociation constant, \({K_{\text{b}}}\), for ammonia.
• 10M.2.hl.TZ1.3d.i: State an equation for the reaction of ethanoic acid with water.
• 10M.2.hl.TZ1.3d.ii: Calculate the pH of \({\text{0.200 mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\) ethanoic acid...
• 09M.1.hl.TZ1.29: What is the approximate pH of a \({\text{0.01 mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\) ammonia...
• 09M.2.hl.TZ1.2a.i: State the equation for the reaction of propanoic acid with water.
• 09M.2.hl.TZ1.2a.ii: Calculate the hydrogen ion concentration (in \({\text{mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\)) of...
• 09M.1.hl.TZ2.26: \({\text{100 c}}{{\text{m}}^{\text{3}}}\) of a NaOH solution of pH 12 is mixed with...
• 09M.1.hl.TZ2.27: Ammonia acts as a weak base when it reacts with water. What is the \({K_{\text{b}}}\) expression...
• 09M.1.hl.TZ2.28: The indicator, HIn is used in a titration between an acid and base. Which statement about the...
• 09M.1.hl.TZ2.29: At the same concentration, which acid would have the lowest...
• 09M.2.hl.TZ2.2a.i: Calculate the \({K_{\text{a}}}\) value of benzoic acid,...
• 09M.2.hl.TZ2.2a.ii: Based on its \({K_{\text{a}}}\) value, state and explain whether benzoic acid is a strong or weak...
• 09M.2.hl.TZ2.2a.iii: Determine the hydrogen ion concentration and the pH of a...
• 11M.1.hl.TZ1.28: The \({K_{\text{b}}}\) value for a base is...
• 11M.1.hl.TZ2.27: Based on information in the table below, which acid is the strongest?
• 11M.2.hl.TZ2.5a.iv: Calculate the pH of a...
• 12M.1.hl.TZ2.24: Four aqueous solutions are listed below. W.    ...
• 12M.2.hl.TZ2.8d: A solution of ammonia has a concentration of...
• 11N.1.hl.TZ0.27: Consider the equation for the dissociation of...
• 11N.2.hl.TZ0.4b.i: The \({\text{p}}{K_{\text{a}}}\) value of HOCl(aq) is 7.52. Determine the \({K_{\text{b}}}\)...
• 11N.2.hl.TZ0.4b.ii: Determine the concentration of \({\text{O}}{{\text{H}}^ - }{\text{(aq)}}\), in...
• 11N.2.hl.TZ0.4b.iii: Calculate the pH of the bleach.
• 16M.2.hl.TZ0.2d: Phenylamine can act as a weak base. Calculate the pH of a 0.0100 mol dm−3 solution of phenylamine...
• 16N.2.hl.TZ0.7a: Calculate the pH of 0.0100 mol dm–3 methanoic acid stating any assumption you make. Ka = 1.6 ×...
• 17M.2.hl.TZ1.5d.i: Hydrazine reacts with water in a similar way to ammonia. (The association of a molecule of...
• 17M.1.hl.TZ2.27: What is the order of increasing acidity of the following acids? A.     chloroethanoic <...
• 17M.2.hl.TZ2.8c: The pKa of an anthocyanin is 4.35. Determine the pH of a 1.60 × 10–3 mol dm–3 solution to two...
• 17N.2.hl.TZ0.6c.i: Calculate [H3O+] in the solution and the dissociation constant, Ka , of the acid at 25 °C.
• 17N.2.hl.TZ0.6c.ii: Calculate Kb for HCO3– acting as a base.
• 18M.2.hl.TZ1.5d: Determine the pH of 0.010 mol dm−3 2,2-dimethylpropanoic acid solution. Ka...
• 18M.1.hl.TZ2.27: What is the order of increasing acidity? A.     HClO < CH3CH2COOH < HF < HIO3 B.   ...
• 18M.2.hl.TZ2.2d.ii: Calculate the pH of 0.100 mol dm−3 aqueous ethanoic acid. Ka = 1.74 × 10−5

18.3 pH curves

• 15M.1.hl.TZ1.29: Which mixture will form a buffer in aqueous solution? A.    ...
• 15M.1.hl.TZ2.29: For which titration can the end point not be determined accurately by using an acid-base...
• 15M.2.hl.TZ1.8c.i: Determine the pH at the equivalence point of the titration and the \({\text{p}}{K_{\text{a}}}\)...
• 15M.2.hl.TZ1.8c.ii: Identify, using table 16 of the data booklet, a suitable indicator to show the end-point of this...
• 15M.2.hl.TZ1.8c.iii: Describe how an indicator, that is a weak acid, works. Use Le Chatelier’s principle in your answer.
• 15M.2.hl.TZ2.4a: Define the term buffer solution.
• 15M.2.hl.TZ2.4b: Explain, using appropriate equations, how this solution acts as a buffer solution.
• 15M.2.hl.TZ2.7g: (i)     Sketch the pH titration curve obtained when \({\text{50.0 c}}{{\text{m}}^{\text{3}}}\) of...
• 14M.1.hl.TZ1.27: Which mixture of solutions can be used to prepare a buffer solution? A.    ...
• 14M.1.hl.TZ1.28: A weak acid is titrated with a strong base. Which statement is true for the titration...
• 14M.1.hl.TZ1.29: Methyl orange is an indicator which changes its colour from red to yellow in a pH range of 3.2 –...
• 14M.1.hl.TZ2.27: Which compounds can be mixed together as aqueous solutions of equal volume and concentration to...
• 14M.1.hl.TZ2.28: Which statements about an acid–base indicator are correct? I.     It can be a weak acid. II.   ...
• 14M.1.hl.TZ2.30: Which graph would be obtained by adding...
• 14M.2.hl.TZ1.7c.ii: A buffer solution is made using \({\text{25.0 c}}{{\text{m}}^{\text{3}}}\) of...
• 14M.2.hl.TZ1.7c.vi: Identify a suitable indicator for this titration, using Table 16 of the Data Booklet.
• 14M.2.hl.TZ2.5b.vi: Describe, using HIn to represent the indicator in its acid form, why an indicator changes colour...
• 14N.1.hl.TZ0.29: The acid–base indicator phenol red, HIn, changes colour from yellow to red over a pH range of...
• 14N.2.hl.TZ0.8f: (i)     Most indicators are weak acids. Describe qualitatively how indicators...
• 13N.1.hl.TZ0.29: Which pair of compounds could be used to make a buffer solution (assuming appropriate molar...
• 13N.2.hl.TZ0.7d.ii: Identify one indicator that could be used when titrating aqueous sodium hydroxide with both a...
• 13N.2.hl.TZ0.7e.i: Explain how the \({\text{p}}{K_{\text{a}}}\) could be determined from a graph of pH against the...
• 13M.1.hl.TZ1.29: The colours of three indicators are shown in the table below. Equal volumes of these three...
• 13M.2.hl.TZ1.1f.i: State what is meant by a buffer solution.
• 13M.2.hl.TZ2.6c.i: State whether the following mixtures, in the appropriate molar ratios, can be classified as...
• 13M.2.hl.TZ2.6d.ii: Using Table 16 of the Data Booklet, identify the most appropriate indicator for the titration of...
• 12N.1.hl.TZ0.29: During a titration, \({\text{0.1 mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\) sodium hydroxide is added...
• 12N.2.hl.TZ0.3a: Describe the composition of an acidic buffer solution.
• 10N.1.hl.TZ0.28: Equal volumes and concentrations of hydrochloric acid and ethanoic acid are titrated with sodium...
• 10N.1.hl.TZ0.29: Bromophenol blue changes from yellow to blue over the pH range of 3.0 to 4.6. Which statement is...
• 10N.2.hl.TZ0.6d: (i)     Calculate the volume of the sodium hydroxide solution required to react exactly with a...
• 09N.1.hl.TZ0.28: Which indicator would be the most appropriate for titrating aqueous ethylamine,...
• 09N.2.hl.TZ0.8a.i: Determine the pH at the equivalence point.
• 09N.2.hl.TZ0.8a.ii: Explain, using an equation, why the equivalence point is not at \({\text{pH}} = 7\).
• 09N.2.hl.TZ0.8a.iv: Estimate, using data from the graph, the dissociation constant, \({K_{\text{a}}}\), of the weak...
• 09N.2.hl.TZ0.8a.v: Suggest an appropriate indicator for this titration.
• 09N.2.hl.TZ0.8c.i: Explain what is meant by the term buffer solution.
• 10M.2.hl.TZ2.7c: (i)     Explain why the pH of the ammonia solution is less than 13. (ii)     Estimate the pH at...
• 09M.1.hl.TZ1.28: Which mixtures could act as buffers? I.     NaOH(aq) and HCl(aq) II.     NaOH(aq) and...
• 09M.2.hl.TZ1.2b: The graph below shows a computer simulation of a titration of...
• 11M.1.hl.TZ1.29: Which compounds can be mixed together as solutions of equal volume and concentration to form a...
• 11M.2.hl.TZ1.8a.iii: The graph below indicates the pH change during the titration of...
• 11M.2.hl.TZ1.8a.iv: Explain how the graph could be used to determine the \({\text{p}}{K_{\text{a}}}\) of ethanoic...
• 11M.2.hl.TZ1.8a.v: Sketch a graph, similar to the graph on the previous page, to indicate the change in pH during a...
• 11M.1.hl.TZ2.29: The graph below shows the titration curve of \({\text{25 c}}{{\text{m}}^{\text{3}}}\) of...
• 11M.2.hl.TZ2.5a.v: \({\text{25.0 c}}{{\text{m}}^{\text{3}}}\) of...
• 11M.2.hl.TZ2.5a.vi: State what is meant by a buffer solution and explain how the solution in (v), which contains...
• 12M.1.hl.TZ2.26: Which mixtures are buffer solutions? I.     \({\text{KHS}}{{\text{O}}_{\text{4}}}{\text{(aq)}}\)...
• 12M.1.hl.TZ2.27: Which titration curve is produced by the titration of \({\text{25 c}}{{\text{m}}^{\text{3}}}\) of...
• 12M.2.hl.TZ2.8d: A solution of ammonia has a concentration of...
• 12M.2.hl.TZ2.8f: (i)     Identify the property of bromocresol green that makes it suitable to use as an acid–base...
• 16M.1.hl.TZ0.29: Which titration curve would...
• 16N.1.hl.TZ0.28: Which mixture is a buffer solution? A.  25 cm3 of 0.10 mol dm-3 NH3 (aq) and 50 cm3 of 0.10 mol...
• 16N.1.hl.TZ0.29: Which salt solution has the highest pH? A. NH4Cl B. Ca(NO3)2 C. Na2CO3 D. K2SO4
• 16N.2.hl.TZ0.7b: (i) Sketch a graph of pH against volume of a strong base added to a weak acid showing how you...
• 17M.1.hl.TZ1.27: A buffer is produced by mixing 20.0 cm3 of 0.10 mol dm−3 ethanoic acid, CH3COOH(aq), with 0.10...
• 17M.2.hl.TZ1.5d.ii: Suggest a suitable indicator for the titration of hydrazine solution with dilute sulfuric acid...
• 17M.2.hl.TZ2.8b.iv: The following curve was obtained using a pH probe. State, giving a reason, the strength of the...
• 17M.2.hl.TZ2.8b.vi: Deduce the pKa for this acid.
• 17N.1.hl.TZ0.26: Which of the following will form a buffer solution if combined in appropriate molar ratios? A....
• 17N.1.hl.TZ0.27: Which indicator is appropriate for the acid-base titration shown below? A. Thymol blue (pKa =...
• 18M.1.hl.TZ1.27: Which combination of acid and base is most likely to have a pH of 8.5 at the equivalence point in...
• 18M.2.hl.TZ1.5e: Explain, using appropriate equations, how a suitably concentrated solution formed by the partial...
• 18M.2.hl.TZ2.2d.i: The graph represents the titration of 25.00 cm3 of 0.100 mol dm−3 aqueous ethanoic acid with...
• 18M.2.hl.TZ2.2d.iv: Predict whether the pH of an aqueous solution of ammonium chloride will be greater than, equal to...