WAEC (WASSCE) Chemistry · Solutions, energy and chemical change
Acids, bases and salts: WAEC Chemistry Past Questions and Answers
What the WAEC syllabus covers in Acids, bases and salts
Our summary: What acids, bases and salts are, how strong they are, the pH scale, indicators, salt hydrolysis and acid-base titration.
- Definitions of acids and bases ((1) Arrhenius concepts of acids and bases in terms of H₃O⁺ and OH⁻ ions in water. (2) Effects of acids and bases on indicators, metal Zn, Fe and trioxocarbonate (IV) salts and hydrogentrioxocarbonate (IV) salts.)
- Physical and chemical properties of acids and bases (Characteristic properties of acids and bases in aqueous solution to include: (a) conductivities, taste, litmus/indicators, feel etc.; (b) balanced chemical equations of all reactions.)
- Acids, bases and salts as electrolytes (Electrolytes and non-electrolytes; strong and weak electrolytes. Evidence from conductivity and enthalpy of neutralization.)
- Classification of acids and bases ((1) Strength of acids and bases. (2) Classify acids and bases into strong and weak. (3) Extent of dissociation reaction with water and conductivity. (4) Behaviour of weak acids and weak bases in water as example of equilibrium systems.)
- Concept of pH ((1) Definition of pH and knowledge of pH scale. (2) Measurement of pH of solutions using pH meter, colorimetric methods or universal indicator. (3) Significance of pH values in everyday life e.g. acid rain, pH of soil, blood, urine.)
- Salts (Meaning of salts. Types of salts: normal, acidic, basic, double and complex salts.)
- Salts: laboratory and industrial preparation of salts; uses ((1) Description of laboratory and industrial production of salts. (2) Mining of impure sodium chloride and conversion into granulated salt. (3) Preparation of NaOH, Cl₂ and H₂.)
- Salts: hydrolysis of salt ((1) Explanation of how salts form acidic, alkaline and neutral aqueous solutions. (2) Behaviour of some salts (e.g. NH₄Cl, AlCl₃, Na₂CO₃, CH₃COONa) in water as examples of equilibrium systems. (3) Effects of charge density of some cations and anions on the hydrolysis of their aqueous solution. Examples to be taken from group 1, group 2, group 3 and the d-block element.)
- Deliquescent, efflorescent and hygroscopic compound (Use of hygroscopic compounds as drying agent should be emphasized.)
- Acid-base indicators ((1) Qualitative description of how acid-base indicator works. (2) Indicators as weak organic acids or bases (organic dyes). (3) Colour of indicator at any pH dependent on relative amounts of acid and base forms. (4) Working pH ranges of methyl orange and phenolphthalein.)
- Acid-base titration ((1) Knowledge and correct use of relevant apparatus. (2) Knowledge of how acid-base indicators work in titrations. (3) Acid-base titration experiments involving HCl, HNO₃, H₂SO₄ and NaOH, KOH, Ca(OH)₂, CO₃²⁻, HCO₃⁻. (4) Titration involving weak acids versus strong bases, strong acids versus weak bases and strong acids versus strong bases using the appropriate indicators and their applications in quantitative determination; e.g. concentrations, mole ratio, purity, water of crystallization and composition.)
Syllabus content © The West African Examinations Council (WASSCE (harmonised West African syllabus)).
WAEC (WASSCE) Chemistry questions on Acids, bases and salts
- WAEC 2024Which of the following household liquids would be effective in treating someone with too much acid in the stomach?
- WAEC 2024Bases normally
- WAEC 2024A weak acid is one which
- WAEC 2024Which of the following statements about ammonium salt is correct? It
- WAEC 2024Pure water contaminated with quicklime will have a pH of
- WAEC 2023An example of a crystalline substance that does not possess water of crystallization is
- WAEC 2023A compound that could be dried by using conc. tetraoxosulphate (VI) acid and not by calcium oxide is likely to be
- WAEC 2023Dilute trioxonitrate (V) acid does not produce hydrogen when it reacts with metals because
- WAEC 2023Which of the following equimolar solutions has the highest conductivity?
- WAEC 2023The best indicator to use for the titration of ethanoic acid with sodium hydroxide is
- WAEC 2023The salt solution formed firm a reaction between ethanoic acid and sodium hydroxide solution would be
- WAEC 2022Consider the following reaction equation: CaO + SiO 2 ------ CaSiO 3 Silicon(IV) oxide is acting as
- WAEC 2022An oxide has the following properties. It I. is a white powder II. reacts with HCI. III. reacts with NaOH IV. is insoluble in water The oxide is
- WAEC 2022Which of the following acids would form normal salt only?
- WAEC 2022Which of the following oxides is amphoteric?
- WAEC 2022Which of the following gases is alkaline?
- WAEC 2022A white precipitate was formed when BaCl 2(aq) was added to an aqueous solution of a salt X. The precipitate dissolved in dilute HCl with rapid effervescence…
- WAEC 2022A colourless gas with a pungent smell is evolved when dilute hydrochloric acid is added to a sample of a salt. The gas evolved could turn
- WAEC 2021The basic property of salts used as drying agents is by?
- WAEC 2021Which of the following pairs of compounds would form a precipitate when their aqueous solutions are mixed?
- WAEC 2021The most common method of preparing insoluble salts is by
- WAEC 2021Student X titrated 25 cm ^ 3 of Na 2 CO ^ 3 with 0.1 mol dm ^ -3 HCI, using methyl orange as indicator. Student Y carried out the same exercise but used…
- WAEC 2021When CuSO 4(aq) is added to Pb(NO 3 ) 2(aq) --------
- WAEC 2020If 20 cm ^3 of sodium hydroxide was neutralized by 20 cm ^3 of 0.01 mol dm ^3 tetraoxosulphate(VI) acid, what is the concentration of the sodium hydroxide…
- WAEC 2020Consider the reaction represented by the following equation: AgNO 3 + NaCl → AgCl + NaNO 3 . The steps that could be taken to obtain pure dry sample of AgCI (s)…
- WAEC 2020Which of the following hydroxides is not readily soluble in water?
- WAEC 2020Which of the following solids would not decompose on heating?
- WAEC 2019which of the following solutions containing one mole per dm ^3 of the compound would have the lowest PH?
- WAEC 2019The most suitable indicator for the reaction between NaOH and HCOOH is?
- WAEC 2019The properties of a good primary standard solution include the following except?
- WAEC 2019A sample of air was bubbled into water. The PH of the water slowly changed from 7 to 6. Which of the following gases in the samples caused the change?
- WAEC 2018When chlorine is passed through a sample of water, the pH of the water sample would be
- WAEC 2018Consider the following reaction equation: 2HCl + Ca(OH) 2 CaCl 2 + H 2 O . What is the volume of 0.1 moldm^ -3 HCl that would completely neutralize 25 cm^ 3 of…
- WAEC 2017Which of the following statements is NOT a chemical property of an acid?
- WAEC 2017Soluble salts can be prepared by the following methods except
- WAEC 2017Which of the following gases is not acidic?
- WAEC 2016Which of the following substances is a non-electrolyte?
- WAEC 2016An aqueous solution of (NH4)2 SO4 is
- WAEC 2016Which of the following salts when dissolved in water will form a solution that will change blue litmus to red?
- WAEC 2016Consider the following reaction equation H3O+(aq) + OH(aq) 2H2O(1) The reaction represents
- WAEC 2015An example of an acid salt is
- WAEC 2014Zinc oxide is said to be amphoteric because it
- WAEC 2014Which of the following substances with the corresponding pH value is an alkali? Substance pH
- WAEC 2014Which of the following salts on hydrolysis would give an alkaline solution?
- WAEC 2014An aqueous solution of Na2CO3 is
- WAEC 2013The aqueous solution which has pH 7 is
- WAEC 2013Which of the following compounds crystallizes without water of crystallization?
- WAEC 2013The major product formed by the reaction between ethanoic acid and aqueous sodium hydroxide is
- WAEC 2013Which of the following acids would readily react with CaCO3 to liberate CO2?
- WAEC 2012Which of the following pH values indicates that a solution is a strong base?
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