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7. Equilibria

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  1. 7.1 Chemical equilibria and dynamic equilibrium

    1. 7.1.1What is meant by a reversible reaction

      • Reactions being equal and the concentration of reactants and products remaining constant - (a) understand what is meant by a reversible reaction - (b) understand what is meant by dynamic equilibrium in terms of the rate of forward and reverse - (c) understand the need for a closed system in order to establish dynamic equilibrium

    2. 7.1.2Le Chatelier’s principle as: if a change

      • Define Le Chatelier’s principle as: if a change is made to a system at dynamic equilibrium, the position of equilibrium moves to minimise this change

    3. 7.1.3Le Chatelier’s principle to deduce (from

      • Use Le Chatelier’s principle to deduce qualitatively (from appropriate information) the effects of changes in temperature, concentration, pressure or presence of a catalyst on a system at equilibrium

    4. 7.1.4Expressions for equilibrium constants

      • Deduce expressions for equilibrium constants in terms of concentrations, K c

    5. 7.1.5The terms mole fraction and partial pressure

      • Use the terms mole fraction and partial pressure

    6. 7.1.6Expressions for equilibrium constants

      • Deduce expressions for equilibrium constants in terms of partial pressures, K p (use of the relationship between Kp and Kc is not required)

    7. 7.1.7The Kc and Kp expressions to carry out

      • Use the Kc and Kp expressions to carry out calculations (such calculations will not require the solving of quadratic equations)

    8. 7.1.8The quantities present at equilibrium

      • Calculate the quantities present at equilibrium, given appropriate data

    9. 7.1.9Whether changes in temperature, concentration

      • State whether changes in temperature, concentration or pressure or the presence of a catalyst affect the value of the equilibrium constant for a reaction

    10. 7.1.10Conditions used in the Haber process

      • Describe/explain: the conditions used in the Haber process and the Contact process, as examples of the importance of an understanding of dynamic equilibrium in the chemical industry and the application of Le Chatelier’s principle

  2. 7.2 Brønsted–Lowry theory of acids and bases

    1. 7.2.1Names and formulas of the common acids

      • State the names and formulas of the common acids, limited to hydrochloric acid, HCl, sulfuric acid, H2SO4, nitric acid, HNO3 and ethanoic acid, CH3COOH

    2. 7.2.2Names and formulas of the common alkalis

      • State the names and formulas of the common alkalis, limited to sodium hydroxide, NaOH, potassium hydroxide, KOH and ammonia, NH3

    3. 7.2.3Brønsted–Lowry theory of acids and bases

      • Describe the Brønsted–Lowry theory of acids and bases

    4. 7.2.4Strong acids and strong bases as fully

      • Describe strong acids and strong bases as fully dissociated in aq. solution and weak acids and weak bases as partially dissociated in aq. solution

    5. 7.2.5Appreciate that, under standard conditions,

      • Appreciate that, under standard conditions, water has pH of 7 , acid solutions pH of below 7 and alkaline solutions pH of above 7

    6. 7.2.6The differences in behaviour between strong

      • Explain qualitatively the differences in behaviour between strong and weak acids including the reaction with a reactive metal and difference in pH values by use of a pH meter, universal indicator or conductivity

    7. 7.2.7Neutralisation reactions occur when H +(aq)

      • Understand: neutralisation reactions occur when H +(aq) and OH–(aq) form H2O(l)

    8. 7.2.8Salts are formed in neutralisation reactions

      • Understand: salts are formed in neutralisation reactions

    9. 7.2.9Sketch the pH titration curves of titrations

      • Sketch the pH titration curves of titrations using combinations of strong and weak acids with strong and weak alkalis

    10. 7.2.10Select suitable indicators for acid-alkali

      • Select suitable indicators for acid-alkali titrations, given appropriate data (p Ka values will not be used)