6. Chemical reactions
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6.1 Physical and chemical changes
6.1.1
• Identify physical and chemical changes, and describe the differences between them
6.2 Rate of reaction
6.2.1Rate changes caused by concentration
• Describe rate changes caused by concentration, gas pressure, solid surface area, temperature and adding/removing catalysts, including enzymes
6.2.2Catalyst increases the rate of a
• State: a catalyst increases the rate of a reaction and is unchanged at the end of a reaction
6.2.3Practical methods for investigating
• Describe practical methods for investigating the rate of a reaction including change in mass of a reactant or a product and the formation of a gas
6.2.4Interpret data
• Interpret data, including graphs, from rate of reaction experiments
6.2.5Collision theory in terms of: (a)
• Describe collision theory in terms of: (a) number of particles per unit volume (b) frequency of collisions between particles (c) kinetic energy of particles (d) activation energy, Ea
6.2.6Rate changes using collision theory
• Explain rate changes using collision theory for concentration, gas pressure, solid surface area, temperature and adding/removing catalysts, including enzymes
6.2.7Catalyst decreases the activation
• State: a catalyst decreases the activation energy, Ea, of a reaction
6.2.8Evaluate practical methods for
• Evaluate practical methods for investigating the rate of a reaction including change in mass of a reactant or a product and the formation of a gas
6.3 Reversible reactions and equilibrium
6.3.1Some chemical reactions are reversible
• State: some chemical reactions are reversible as shown by the symbol ⇌
6.3.2Changing the conditions can change the
• Describe how changing the conditions can change the direction of a reversible reaction for: (a) the effect of heat on hydrated compounds (b) the addition of water to anhydrous compounds limited to copper(II) sulfate and cobalt(II) chloride
6.3.3Reversible reaction in a closed system
• State: a reversible reaction in a closed system is at equilibrium when: (a) the rate of the forward reaction is equal to the rate of the reverse reaction (b) the concentrations of reactants and products are no longer changing
6.3.4Predict and explain, for a reversible
• Predict and explain, for a reversible reaction, how the position of equilibrium is affected by: (a) changing temperature (b) changing pressure (c) changing concentration (d) using a catalyst using information provided
6.3.5Symbol equation for the production of
• State the symbol equation for the production of ammonia in the Haber process, N2(g) + 3H2(g) ⇌ 2NH3(g)
6.3.6Sources of the hydrogen (methane) and
• State the sources of the hydrogen (methane) and nitrogen (air) in the Haber process
6.3.7Typical conditions in the Haber
• State the typical conditions in the Haber process as 450 °C, 20 000 kPa/200 atm and an iron catalyst
6.3.8Symbol equation for the conversion of
• State the symbol equation for the conversion of sulfur dioxide to sulfur trioxide in the Contact process, 2SO2(g) + O2(g) ⇌ 2SO3(g)
6.3.9Sources of the sulfur dioxide (burning
• State the sources of the sulfur dioxide (burning sulfur or roasting sulfide ores) and oxygen (air) in the Contact process
6.3.10Typical conditions for the conversion
• State the typical conditions for the conversion of sulfur dioxide to sulfur trioxide in the Contact process as 450 °C, 200 kPa/2 atm and a vanadium(V) oxide catalyst
6.3.11Typical Haber and Contact process
• Explain why typical Haber and Contact process conditions are used, considering reaction rate, equilibrium position, safety and economics
6.4 Redox
6.4.1Roman numeral to indicate the
• Use a Roman numeral to indicate the oxidation number of an element in a compound
6.4.2Redox reactions as involving
• Define redox reactions as involving simultaneous oxidation and reduction
6.4.3Oxidation as gain of oxygen and
• Define oxidation as gain of oxygen and reduction as loss of oxygen
6.4.4Redox reactions as reactions involving
• Identify redox reactions as reactions involving gain and loss of oxygen
6.4.5Oxidation and reduction in redox
• Identify oxidation and reduction in redox reactions
6.4.6Oxidation in terms of: (a) loss of
• Define oxidation in terms of: (a) loss of electrons (b) an increase in oxidation number
6.4.7Reduction in terms of: (a) gain of
• Define reduction in terms of: (a) gain of electrons (b) a decrease in oxidation number
6.4.8Redox reactions as reactions involving
• Identify redox reactions as reactions involving gain and loss of electrons
6.4.9Redox using oxidation numbers: (a)
• Identify redox using oxidation numbers: (a) uncombined elements are 0 (b) monatomic ion number equals ion charge (c) compound total is 0 (d) ion total equals ion charge
6.4.10Redox reactions by the colour changes
• Identify redox reactions by the colour changes involved when using acidified aqueous potassium manganate(VII) or aqueous potassium iodide
6.4.11An oxidising agent as a substance that
• Define an oxidising agent as a substance that oxidises another substance and is itself reduced
6.4.12Reducing agent as a substance that
• Define a reducing agent as a substance that reduces another substance and is itself oxidised
6.4.13Oxidising agents and reducing agents
• Identify oxidising agents and reducing agents in redox reactions