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Chemical Energetics

Each subtopic includes About section, revision page link, 10 preview questions, and practice CTAs.

Exothermic and endothermic reactions

Subtopic

Exothermic and endothermic reactions under Chemical Energetics for Grade 12 IGCSE.

About Topic & Revision

Preview questions (no answers)

  1. 1.

    The enthalpy of formation of an element in its standard state (e.g., O2(g)O_2(g)) is defined as:

    A.

    100kJ/mol100 kJ/mol

    B.

    0kJ/mol0 kJ/mol

    C.

    −100kJ/mol-100 kJ/mol

    D.

    25kJ/mol25 kJ/mol

  2. 2.

    What must be true for a reaction to be classified as endothermic?

    A.

    The energy of the products is less than the energy of the reactants.

    B.

    The temperature of the surroundings increases.

    C.

    The system absorbs heat from the surroundings.

    D.

    The ΔH\Delta H value is negative.

  3. 3.

    Which of these is a typical example of an exothermic reaction?

    A.

    Reaction between citric acid and baking soda

    B.

    Thermal decomposition of potassium chlorate

    C.

    Reaction between zinc and sulfuric acid

    D.

    Photosynthesis in a leaf

Download the worksheet for Chemical Energetics - Exothermic and endothermic reactions to practice offline. It includes additional chapter-level practice questions.

Enthalpy changes

Subtopic

Enthalpy changes under Chemical Energetics for Grade 12 IGCSE.

About Topic & Revision

Preview questions (no answers)

  1. 1.

    What is the standard state of oxygen at 298 K298\text{ K} and 100 kPa100\text{ kPa}?

    A.

    Liquid (ll)

    B.

    Gas (gg)

    C.

    Solid (ss)

    D.

    Aqueous (aqaq)

  2. 2.

    In a calorimetry experiment, the 'surroundings' usually refers to:

    A.

    The reactants

    B.

    The water or solution in the calorimeter

    C.

    The chemical bonds

    D.

    The atmosphere only

  3. 3.

    Which factor describes the heat energy change of a reaction carried out at constant pressure?

    A.

    Entropy

    B.

    Enthalpy

    C.

    Internal Energy

    D.

    Temperature

Download the worksheet for Chemical Energetics - Enthalpy changes to practice offline. It includes additional chapter-level practice questions.

Bond energies

Subtopic

Bond energies under Chemical Energetics for Grade 12 IGCSE.

About Topic & Revision

Preview questions (no answers)

  1. 1.

    What happens to the temperature of the surroundings during an endothermic reaction?

    A.

    It increases.

    B.

    It decreases.

    C.

    It remains constant.

    D.

    It doubles.

  2. 2.

    Calculate the DeltaH\\Delta H for a reaction where the reactant bond energies sum to 2000 kJ/mol2000\ kJ/mol and product bond energies sum to 2500 kJ/mol2500\ kJ/mol.

    A.

    +500 kJ/mol+500\ kJ/mol

    B.

    −500 kJ/mol-500\ kJ/mol

    C.

    +4500 kJ/mol+4500\ kJ/mol

    D.

    −4500 kJ/mol-4500\ kJ/mol

  3. 3.

    Which equation correctly represents the breaking of a fluorine molecule bond?

    A.

    F2(g)rightarrow2F(g)F_2(g) \\rightarrow 2F(g)

    B.

    F2(l)rightarrowF2(g)F_2(l) \\rightarrow F_2(g)

    C.

    2F(g)rightarrowF2(g)2F(g) \\rightarrow F_2(g)

    D.

    F2(g)rightarrowF2+(g)+e−F_2(g) \\rightarrow F_2^+(g) + e^-

Download the worksheet for Chemical Energetics - Bond energies to practice offline. It includes additional chapter-level practice questions.

Chemical Energetics - Grade 12 Chemistry (IGCSE) | Krit.club