Characteristic Properties of Acids and BasesCambridge IGCSE Chemistry: Flashcards

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What are the characteristic properties of acids in terms of their reactions with metals?

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What are the characteristic properties of acids in terms of their reactions with metals?: Acids react with metals to produce a salt and hydrogen gas. For example: 2HCl(aq) + Zn(s) → ZnCl₂(aq) + H₂(g)
What are the characteristic properties of acids in terms of their reactions with bases?: Acids react with bases to produce a salt and water in a neutralisation reaction. For example: HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)
What are the characteristic properties of acids in terms of their reactions with carbonates?: Acids react with carbonates to produce a salt, water and carbon dioxide gas. For example: 2HCl(aq) + CaCO₃(s) → CaCl₂(aq) + H₂O(l) + CO₂(g)
Describe the effect of acids on litmus, thymolphthalein and methyl orange.: Acids turn blue litmus red, thymolphthalein colourless, and methyl orange red.
Define the difference between a base and an alkali.: A base is an oxide or hydroxide of a metal. An alkali is a soluble base that dissolves in water to produce hydroxide ions (OH⁻).
What are the characteristic properties of bases in terms of their reactions with acids?: Bases react with acids in a neutralisation reaction to produce a salt and water. For example: NaOH(aq) + HCl(aq) → NaCl(aq) + H₂O(l)
What are the characteristic properties of bases in terms of their reactions with ammonium salts?: Bases react with ammonium salts when heated to produce ammonia gas, a salt and water. For example: 2NH₄Cl(s) + Ca(OH)₂(s) → 2NH₃(g) + CaCl₂(s) + 2H₂O(l)
Describe the effect of alkalis on litmus, thymolphthalein and methyl orange.: Alkalis turn red litmus blue, thymolphthalein blue, and methyl orange yellow.
What ions are present in aqueous solutions of acids and alkalis?: Aqueous solutions of acids contain H⁺ ions (hydrogen ions). Aqueous solutions of alkalis contain OH⁻ ions (hydroxide ions).
How can universal indicator paper be used to compare hydrogen ion concentration and pH?: Universal indicator paper changes colour across the pH scale (0-14). It is used to determine pH values: below 7 is acidic, 7 is neutral, above 7 is alkaline. Different colours indicate different pH values and relative H⁺ ion concentrations.
Write the ionic equation for neutralisation.: H⁺(aq) + OH⁻(aq) → H₂O(l)
Define an acid in terms of proton transfer.: An acid is a proton donor; it donates H⁺ ions (protons) to other substances.
Define a base in terms of proton transfer.: A base is a proton acceptor; it accepts H⁺ ions (protons) from acids.
What is the difference between a strong acid and a weak acid?: A strong acid is completely dissociated in aqueous solution, meaning all molecules ionise. A weak acid is partially dissociated in aqueous solution, meaning only some molecules ionise and an equilibrium is established.
Write the equation showing hydrochloric acid as a strong acid.: HCl(aq) → H⁺(aq) + Cl⁻(aq) (A single forward arrow shows complete dissociation)
Write the equation showing ethanoic acid as a weak acid.: CH₃COOH(aq) ⇌ H⁺(aq) + CH₃COO⁻(aq) (A reversible arrow shows partial dissociation and equilibrium)