Source: https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-4-3-commercial-application-a2-only

[Revision notes](https://senecalearning.com/en-gb/revision-notes.md) › [A Level](https://senecalearning.com/en-gb/revision-notes/a-level.md) › [Chemistry](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry.md) › [AQA](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa.md) › Commercial Application (A2 Only)

# Commercial Application (A2 Only)

Chemistry: AQA A Level, topic 2.4.3

## Batteries

Electrochemical cells are used as batteries.

### Batteries

![Batteries](https://image-v2.cdn.app.senecalearning.com/courseImages/chemistry/5.2.1%20Chemical%20cells%20and%20/battery-1930820_640-min.jpg)

- Batteries come in two forms:
 - Rechargeable.
 - Non-rechargeable.
- Rechargeable batteries can have their reaction reversed by applying an electrical current.
 - This needs more sophisticated cells and is more expensive. But this process can be cheaper overall as you only need to buy one.

### Lithium cobalt oxide batteries

![Lithium cobalt oxide batteries](https://image-v2.cdn.app.senecalearning.com/courseImages/chemistry/5.2.1%20Chemical%20cells%20and%20/battery-1930820_640-min.jpg)

- LiCoO2 batteries were the first lithium ion batteries invented.
- They have one electrode made of LiCoO2 and one made of graphite.
- The two half equations are:
 - Li+ + e- ⇌ Li(s), Eθ = −3.04V
 - Li+ + CoO2 + e- ⇌ LiCoO2, Eθ = 0.56V

### The reactions

![The reactions](https://image-v2.cdn.app.senecalearning.com/courseImages/chemistry/5.2.1%20Chemical%20cells%20and%20/battery-1930820_640-min.jpg)

- The Li+/Li(s) cell has a more negative Eθ so is reversed.
- The overall cell potential is: Eθcell = 0.56 − (−3.04) = 3.6V.
 - To reverse the reaction, you apply an external current of at least 3.6V to push the reactions in the opposite directions.

## Fuel Cells

Fuel cells can be used to make electricity. They store the chemicals outside of the cell and put them in when we want electricity.

### The hydrogen-oxygen fuel cell

![The hydrogen-oxygen fuel cell](https://image-v2.cdn.app.senecalearning.com/2019-02/b214d93f-fd13-4581-8ec7-84658d81c03b/fuel-cells.jpg)

- The most important fuel cell is the alkaline hydrogen-oxygen fuel cell.
 - Hydrogen and oxygen are the fuel.
 - The electrodes are platinum electrodes.

### Diagram

![Diagram](https://image-v2.cdn.app.senecalearning.com/2019-02/6dd3e150-15ad-4009-9f6a-ac39a32b3e29/fuel-cells.jpg)

### Anion exchange membranes

![Anion exchange membranes](https://image-v2.cdn.app.senecalearning.com/2019-02/657791e8-36cb-41fc-976c-2babd9df8ceb/fuel-cells.jpg)

- The anion exchange membranes do NOT allow the gases through.
- These membranes do allow hydroxide ions (OH-) and water to pass through.

### At the electrodes

![At the electrodes](https://image-v2.cdn.app.senecalearning.com/2019-02/1621e9ac-87a2-4fae-ba99-d846b5aee06c/fuel-cells.jpg)

- The hydrogen gas is delivered to the negative electrode where it reacts with the hydroxide ions. The half equation for this reaction is:
 - 2H2(g) + 4OH-(aq) → 4H2O(l) + 4e-
- The oxygen gas is delivered to the positive electrode where it reacts with water and electrons. The half equation for this reaction is:
 - O2(g) + 2H2O(l) + 4e- → 4OH-(aq)

### Overall reaction

![Overall reaction](https://image-v2.cdn.app.senecalearning.com/2018-09/8b73aef4-2f5f-4bdb-875e-075afb705df1/water-molecule-h2o-.jpg)

- The overall reaction for the hydrogen-oxygen fuel cell is:
 - 2H2(g) + O2(g) → 2H2O(g)

## Advantages and Disadvantages of Fuel Cells

Fuel cells can be better electricity-generating devices than the internal combustion engines that are found in cars.

### Advantages of fuel cells

![Advantages of fuel cells](https://image-v2.cdn.app.senecalearning.com/2018-08/c12adfda-0b11-4675-abb3-022d9e0407c6/efficiency-.jpg)

- Fuel cells have a high efficiency.
 - This means that they get more energy out of the same amount of fuel than less efficient devices.
- Their only by-product is water (no CO2(g) is produced).
- They don’t need to be recharged - they will work as long as the fuel is supplied.

### Disadvantages of fuel cells

![Disadvantages of fuel cells](https://image-v2.cdn.app.senecalearning.com/courseImages/chemistry/3.1.1%20-%20Relative%20formula%20mass/fire-1707042_640-min.jpg)

- Hydrogen is flammable and so must be stored very carefully.
- Energy is needed to produce the reactants of hydrogen and oxygen.
 - This energy usually comes from fossil fuels, so there are some CO2(g) emissions.

## Test yourself on Commercial Application (A2 Only)

- What's the downside to rechargeable batteries?
- Which of these accurately describes what a fuel cell does?
- What is the overall reaction for the alkaline hydrogen-oxygen fuel cell?
- Fuel cells do NOT produce CO2. What do they produce instead?
- What is the main risk when handling hydrogen?

[Practise this topic for free](https://app.senecalearning.com/classroom/course/89dad2dd-9f68-460c-9247-131aea534bdb/section/09240d68-ba52-4ba3-8fdf-772f2c29a9c9/session)

- Previous topic: [2.4.2 Electrochemical Series (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-4-2-electrochemical-series-a2-only.md)
- Next topic: [2.4.4 End of Topic Test - Kp & Electrochemistry](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-4-4-end-of-topic-test-kp-and-electrochemistry.md)

## Chemistry: AQA A Level contents

### 1 Physical Chemistry
- 1.1 Atomic Structure
  - [1.1.1 Fundamental Particles](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-1-1-fundamental-particles.md)
  - [1.1.2 Isotopes & Mass Number](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-1-2-isotopes-and-mass-number.md)
  - [1.1.3 Mass Spectrometry](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-1-3-mass-spectrometry.md)
  - [1.1.4 Electron Shells, Sub-Shells & Orbitals](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-1-4-electron-shells-sub-shells-and-orbitals.md)
  - [1.1.5 Electron Configuration](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-1-5-electron-configuration.md)
  - [1.1.6 Ionisation Energy](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-1-6-ionisation-energy.md)
  - [1.1.7 Factors Affecting Ionisation Energies](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-1-7-factors-affecting-ionisation-energies.md)
  - [1.1.8 Trends of Ionisation](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-1-8-trends-of-ionisation.md)
  - [1.1.9 Specific Impacts on Ionisation Energies](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-1-9-specific-impacts-on-ionisation-energies.md)
  - [1.1.10 End of Topic Test - Atomic Structure](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-1-10-end-of-topic-test-atomic-structure.md)
  - [1.1.11 A-A* (AO3/4) - Atomic Structure](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-1-11-a-a-ao34-atomic-structure.md)
- 1.2 Amount of Substance
  - [1.2.1 Relative Masses](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-2-1-relative-masses.md)
  - [1.2.2 The Mole](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-2-2-the-mole.md)
  - [1.2.3 The Ideal Gas Equation](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-2-3-the-ideal-gas-equation.md)
  - [1.2.4 Empirical & Molecular Formulae](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-2-4-empirical-and-molecular-formulae.md)
  - [1.2.5 Balanced Equations](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-2-5-balanced-equations.md)
  - [1.2.6 Percentage Yield](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-2-6-percentage-yield.md)
  - [1.2.7 A-A* (AO3/4) - Percentage Yield](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-2-7-a-a-ao34-percentage-yield.md)
  - [1.2.8 Atom Economy](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-2-8-atom-economy.md)
  - [1.2.9 End of Topic Test - Amount of Substance](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-2-9-end-of-topic-test-amount-of-substance.md)
  - [1.2.10 A-A* (AO3/4) - Substances & Yield](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-2-10-a-a-ao34-substances-and-yield.md)
  - [1.2.11 Diagnostic Misconceptions - Moles](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-2-11-diagnostic-misconceptions-moles.md)
- 1.3 Bonding
  - [1.3.1 Ionic Bonding](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-3-1-ionic-bonding.md)
  - [1.3.2 Covalent & Dative Bonding](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-3-2-covalent-and-dative-bonding.md)
  - [1.3.3 Carbon Structures](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-3-3-carbon-structures.md)
  - [1.3.4 Metallic Bonding](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-3-4-metallic-bonding.md)
  - [1.3.5 Physical Properties](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-3-5-physical-properties.md)
  - [1.3.6 Shapes of Molecules](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-3-6-shapes-of-molecules.md)
  - [1.3.7 Polarity](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-3-7-polarity.md)
  - [1.3.8 Intermolecular Forces](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-3-8-intermolecular-forces.md)
  - [1.3.9 Intermolecular Forces 2](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-3-9-intermolecular-forces-2.md)
  - [1.3.10 End of Topic Test - Bonding](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-3-10-end-of-topic-test-bonding.md)
  - [1.3.11 Exam-Style Question - Shape of Molecules](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-3-11-exam-style-question-shape-of-molecules.md)
  - [1.3.12 A-A* (AO3/4) - Bonding](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-3-12-a-a-ao34-bonding.md)
  - [1.3.13 Diagnostic Misconceptions - Ions](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-3-13-diagnostic-misconceptions-ions.md)
  - [1.3.14 Diagnostic Misconceptions - Ionic & Covalent](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-3-14-diagnostic-misconceptions-ionic-and-covalent.md)
  - [1.3.15 Diagnostic Misconceptions - Phase Change](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-3-15-diagnostic-misconceptions-phase-change.md)
  - [1.3.16 Diagnostic Misconceptions - Boiling](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-3-16-diagnostic-misconceptions-boiling.md)
  - [1.3.17 Diagnostic Misconceptions - Polar Bonds](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-3-17-diagnostic-misconceptions-polar-bonds.md)
- 1.4 Energetics
  - [1.4.1 Enthalpy Changes](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-4-1-enthalpy-changes.md)
  - [1.4.2 Bond Breaking and Making](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-4-2-bond-breaking-and-making.md)
  - [1.4.3 Enthalpy Changes: Standard Conditions](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-4-3-enthalpy-changes-standard-conditions.md)
  - [1.4.4 Calorimetry](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-4-4-calorimetry.md)
  - [1.4.5 Hess' Law](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-4-5-hess-law.md)
  - [1.4.6 Bond Enthalpies](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-4-6-bond-enthalpies.md)
  - [1.4.7 End of Topic Test - Energetics](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-4-7-end-of-topic-test-energetics.md)
  - [1.4.8 Diagnostic Misconceptions - Calorimetry](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-4-8-diagnostic-misconceptions-calorimetry.md)
- 1.5 Kinetics
  - [1.5.1 Collision Theory](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-5-1-collision-theory.md)
  - [1.5.2 Maxwell-Boltzmann Distribution](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-5-2-maxwell-boltzmann-distribution.md)
  - [1.5.3 Increasing Rates](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-5-3-increasing-rates.md)
  - [1.5.4 End of Topic Test - Kinetics](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-5-4-end-of-topic-test-kinetics.md)
- 1.6 Equilibria
  - [1.6.1 Le Chatelier](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-6-1-le-chatelier.md)
  - [1.6.2 Equilibrium Constants](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-6-2-equilibrium-constants.md)
  - [1.6.3 A-A* (AO3/4) - Energetics, Kinetics, Equilibria](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-6-3-a-a-ao34-energetics-kinetics-equilibria.md)
  - [1.6.4 End of Topic Test - Equilibria](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-6-4-end-of-topic-test-equilibria.md)
  - [1.6.5 Diagnostic Misconceptions - Solids](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-6-5-diagnostic-misconceptions-solids.md)
- 1.7 Redox
  - [1.7.1 Redox](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-7-1-redox.md)
  - [1.7.2 End of Topic Test - Redox](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/1-7-2-end-of-topic-test-redox.md)

### 2 Physical Chemistry 2 (A2 Only)
- 2.1 Thermodynamics (A2 Only)
  - [2.1.1 Born-Haber Cycles (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-1-1-born-haber-cycles-a2-only.md)
  - [2.1.2 Born-Haber Cycle Calculations (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-1-2-born-haber-cycle-calculations-a2-only.md)
  - [2.1.3 Entropy (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-1-3-entropy-a2-only.md)
  - [2.1.4 Free Energy (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-1-4-free-energy-a2-only.md)
  - [2.1.5 End of Topic Test - Thermodynamics](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-1-5-end-of-topic-test-thermodynamics.md)
  - [2.1.6 A-A* (AO3/4) - Thermodynamics](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-1-6-a-a-ao34-thermodynamics.md)
- 2.2 Rate Equations (A2 Only)
  - [2.2.1 Rate Equations (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-2-1-rate-equations-a2-only.md)
  - [2.2.2 Rate Equations 2 (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-2-2-rate-equations-2-a2-only.md)
  - [2.2.3 The Arrhenius Equation (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-2-3-the-arrhenius-equation-a2-only.md)
  - [2.2.4 Experimental Methods for Rates (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-2-4-experimental-methods-for-rates-a2-only.md)
  - [2.2.5 End of Topic Test - Rate Equations](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-2-5-end-of-topic-test-rate-equations.md)
  - [2.2.6 Exam-Style Question - Rates](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-2-6-exam-style-question-rates.md)
  - [2.2.7 A-A* (AO3/4) - Rate Equations](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-2-7-a-a-ao34-rate-equations.md)
- 2.3 The Equilibrium Constant Kp (A2 Only)
  - [2.3.1 Properties of Kp (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-3-1-properties-of-kp-a2-only.md)
- 2.4 Electrochemical Cells (A2 Only)
  - [2.4.1 Electrochemical Cells (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-4-1-electrochemical-cells-a2-only.md)
  - [2.4.2 Electrochemical Series (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-4-2-electrochemical-series-a2-only.md)
  - [2.4.3 Commercial Application (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-4-3-commercial-application-a2-only.md)
  - [2.4.4 End of Topic Test - Kp & Electrochemistry](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-4-4-end-of-topic-test-kp-and-electrochemistry.md)
  - [2.4.5 A-A* (AO3/4) - Electrochemical Cells](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-4-5-a-a-ao34-electrochemical-cells.md)
  - [2.4.6 Diagnostic Misconceptions - Salt Bridges](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-4-6-diagnostic-misconceptions-salt-bridges.md)
  - [2.4.7 Diagnostic Misconceptions - Electrode, Electrolyte](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-4-7-diagnostic-misconceptions-electrode-electrolyte.md)
- 2.5 Acids & Bases (A2 Only)
  - [2.5.1 Brønsted-Lowry Acids & Bases (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-5-1-bronsted-lowry-acids-and-bases-a2-only.md)
  - [2.5.2 pH (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-5-2-ph-a2-only.md)
  - [2.5.3 The Ionic Product of Water (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-5-3-the-ionic-product-of-water-a2-only.md)
  - [2.5.4 Weak Acids & Bases (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-5-4-weak-acids-and-bases-a2-only.md)
  - [2.5.5 pH Curves & Titrations (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-5-5-ph-curves-and-titrations-a2-only.md)
  - [2.5.6 pH Curves & Titrations 2 (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-5-6-ph-curves-and-titrations-2-a2-only.md)
  - [2.5.7 Buffer Solutions (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-5-7-buffer-solutions-a2-only.md)
  - [2.5.8 End of Topic Test - Acids & Bases](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-5-8-end-of-topic-test-acids-and-bases.md)
  - [2.5.9 Exam-Style Question - Weak Acids](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-5-9-exam-style-question-weak-acids.md)
  - [2.5.10 A-A* (AO3/4) - Acids & Bases](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-5-10-a-a-ao34-acids-and-bases.md)
  - [2.5.11 Diagnostic Misconceptions - Ammonia is an Alkali](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-5-11-diagnostic-misconceptions-ammonia-is-an-alkali.md)
  - [2.5.12 Diagnostic Misconceptions - Water's Neutrality](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-5-12-diagnostic-misconceptions-waters-neutrality.md)
  - [2.5.13 Diagnostic Misconceptions - Concentrate & Strength](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/2-5-13-diagnostic-misconceptions-concentrate-and-strength.md)

### 3 Inorganic Chemistry
- 3.1 Periodicity & Trends
  - [3.1.1 The Periodic Table](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/3-1-1-the-periodic-table.md)
  - [3.1.2 Trends in the Periodic Table](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/3-1-2-trends-in-the-periodic-table.md)
  - [3.1.3 End of Topic Test - Periodicity & Trends](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/3-1-3-end-of-topic-test-periodicity-and-trends.md)
  - [3.1.4 Diagnostic Misconceptions - Atomic Radius](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/3-1-4-diagnostic-misconceptions-atomic-radius.md)
- 3.2 Group 2
  - [3.2.1 Group 2 Chemistry](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/3-2-1-group-2-chemistry.md)
  - [3.2.2 End of Topic Test - Group 2](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/3-2-2-end-of-topic-test-group-2.md)
- 3.3 Group 7
  - [3.3.1 Introduction to Halogens](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/3-3-1-introduction-to-halogens.md)
  - [3.3.2 Reactions of Halogens](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/3-3-2-reactions-of-halogens.md)
  - [3.3.3 Chlorine & Chlorate(I)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/3-3-3-chlorine-and-chloratei.md)
  - [3.3.4 End of Topic Test - Group 7](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/3-3-4-end-of-topic-test-group-7.md)
  - [3.3.5 Exam-Style Question - Group 7](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/3-3-5-exam-style-question-group-7.md)
  - [3.3.6 A-A* (AO3/4) - Periodicity, Group 2 & 7](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/3-3-6-a-a-ao34-periodicity-group-2-and-7.md)

### 4 Inorganic Chemistry 2 (A2 Only)
- 4.1 Period 3 (A2 Only)
  - [4.1.1 Period 3 Elements & Oxides (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/4-1-1-period-3-elements-and-oxides-a2-only.md)
  - [4.1.2 Period 3 Oxides (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/4-1-2-period-3-oxides-a2-only.md)
  - [4.1.3 End of Topic Test - Period 3](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/4-1-3-end-of-topic-test-period-3.md)
- 4.2 Transition Metals (A2 Only)
  - [4.2.1 General Properties (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/4-2-1-general-properties-a2-only.md)
  - [4.2.2 Substitution Reactions (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/4-2-2-substitution-reactions-a2-only.md)
  - [4.2.3 Shapes of Complex Ions (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/4-2-3-shapes-of-complex-ions-a2-only.md)
  - [4.2.4 Colours of Ions (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/4-2-4-colours-of-ions-a2-only.md)
  - [4.2.5 Variable Oxidation States (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/4-2-5-variable-oxidation-states-a2-only.md)
  - [4.2.6 Titrations (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/4-2-6-titrations-a2-only.md)
  - [4.2.7 Homogeneous Catalysts (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/4-2-7-homogeneous-catalysts-a2-only.md)
  - [4.2.8 Heterogeneous Catalysts (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/4-2-8-heterogeneous-catalysts-a2-only.md)
  - [4.2.9 End of Topic Test - Transition Metals](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/4-2-9-end-of-topic-test-transition-metals.md)
  - [4.2.10 A-A* (AO3/4) - Transition Metals](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/4-2-10-a-a-ao34-transition-metals.md)
- 4.3 Reactions of Ions in Aqueous Solutions (A2 Only)
  - [4.3.1 Acidity (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/4-3-1-acidity-a2-only.md)
  - [4.3.2 Identification (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/4-3-2-identification-a2-only.md)
  - [4.3.3 End of Topic Test - Reactions of Ions in Solution](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/4-3-3-end-of-topic-test-reactions-of-ions-in-solution.md)

### 5 Organic Chemistry 1
- 5.1 Introduction
  - [5.1.1 Naming Conventions](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-1-1-naming-conventions.md)
  - [5.1.2 Mechanism](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-1-2-mechanism.md)
  - [5.1.3 Isomerism](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-1-3-isomerism.md)
  - [5.1.4 End of Topic Test - Introduction to Organic Chem](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-1-4-end-of-topic-test-introduction-to-organic-chem.md)
- 5.2 Alkanes
  - [5.2.1 Fractional Distillation](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-2-1-fractional-distillation.md)
  - [5.2.2 Cracking](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-2-2-cracking.md)
  - [5.2.3 Combustion](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-2-3-combustion.md)
  - [5.2.4 Chlorination](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-2-4-chlorination.md)
  - [5.2.5 End of Topic Test - Alkanes](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-2-5-end-of-topic-test-alkanes.md)
- 5.3 Halogenoalkanes
  - [5.3.1 Substitution Reactions](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-3-1-substitution-reactions.md)
  - [5.3.2 Elimination Reactions](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-3-2-elimination-reactions.md)
  - [5.3.3 Ozone Depletion](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-3-3-ozone-depletion.md)
  - [5.3.4 End of Topic Test - Halogenoalkanes](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-3-4-end-of-topic-test-halogenoalkanes.md)
- 5.4 Alkenes
  - [5.4.1 Introduction to Alkenes](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-4-1-introduction-to-alkenes.md)
  - [5.4.2 Reactions of Alkenes](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-4-2-reactions-of-alkenes.md)
  - [5.4.3 Polymerisation Reactions](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-4-3-polymerisation-reactions.md)
  - [5.4.4 Properties of Polymers](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-4-4-properties-of-polymers.md)
  - [5.4.5 End of Topic Test - Alkenes](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-4-5-end-of-topic-test-alkenes.md)
- 5.5 Alcohols
  - [5.5.1 Production of Alcohols](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-5-1-production-of-alcohols.md)
  - [5.5.2 Oxidation of Alcohols](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-5-2-oxidation-of-alcohols.md)
  - [5.5.3 Oxidation of Alcohols - 2](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-5-3-oxidation-of-alcohols-2.md)
  - [5.5.4 Elimination Reactions](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-5-4-elimination-reactions.md)
  - [5.5.5 End of Topic Test - Alcohols](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-5-5-end-of-topic-test-alcohols.md)
  - [5.5.6 Exam-Style Question - Alcohols](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-5-6-exam-style-question-alcohols.md)
- 5.6 Organic Analysis
  - [5.6.1 Reactions](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-6-1-reactions.md)
  - [5.6.2 Reactions 2](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-6-2-reactions-2.md)
  - [5.6.3 Mass Spectrometry](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-6-3-mass-spectrometry.md)
  - [5.6.4 Infrared Spectroscopy](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-6-4-infrared-spectroscopy.md)
  - [5.6.5 End of Topic Test - Organic Analysis](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-6-5-end-of-topic-test-organic-analysis.md)
- 5.7 A-A* (AO3/4) - Organic 1
  - [5.7.1 A-A* (AO3/4) - Organic 1](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/5-7-1-a-a-ao34-organic-1.md)

### 6 Organic Chemistry 2 (A2 Only)
- 6.1 Optical Isomerism (A2 Only)
  - [6.1.1 Optical Isomerism (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-1-1-optical-isomerism-a2-only.md)
  - [6.1.2 End of Topic Test - Optical Isomerism](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-1-2-end-of-topic-test-optical-isomerism.md)
- 6.2 Aldehydes & Ketones (A2 Only)
  - [6.2.1 Aldehydes & Ketones (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-2-1-aldehydes-and-ketones-a2-only.md)
  - [6.2.2 End of Topic Test - Aldehydes & Ketones](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-2-2-end-of-topic-test-aldehydes-and-ketones.md)
- 6.3 Carboxylic Acids & Esters (A2 Only)
  - [6.3.1 Acids & Esters (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-3-1-acids-and-esters-a2-only.md)
  - [6.3.2 Acylation (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-3-2-acylation-a2-only.md)
  - [6.3.3 End of Topic Test - Carboxylic Acids & Esters](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-3-3-end-of-topic-test-carboxylic-acids-and-esters.md)
- 6.4 Aromatic Chemistry (A2 Only)
  - [6.4.1 Structure & Reactivity (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-4-1-structure-and-reactivity-a2-only.md)
  - [6.4.2 Reactions of Benzene (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-4-2-reactions-of-benzene-a2-only.md)
  - [6.4.3 End of Topic Test - Aromatic Chemistry](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-4-3-end-of-topic-test-aromatic-chemistry.md)
- 6.5 Amines (A2 Only)
  - [6.5.1 Nature & Preparation of Amines (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-5-1-nature-and-preparation-of-amines-a2-only.md)
  - [6.5.2 Basicity & Nucleophilicity (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-5-2-basicity-and-nucleophilicity-a2-only.md)
  - [6.5.3 End of Topic Test - Amines](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-5-3-end-of-topic-test-amines.md)
- 6.6 Polymers (A2 Only)
  - [6.6.1 Condensation Polymers (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-6-1-condensation-polymers-a2-only.md)
  - [6.6.2 Biodegradability (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-6-2-biodegradability-a2-only.md)
- 6.7 Biological Organic (A2 Only)
  - [6.7.1 Amino Acids (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-7-1-amino-acids-a2-only.md)
  - [6.7.2 Proteins (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-7-2-proteins-a2-only.md)
  - [6.7.3 DNA (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-7-3-dna-a2-only.md)
  - [6.7.4 Anti-Cancer Drugs (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-7-4-anti-cancer-drugs-a2-only.md)
  - [6.7.5 End of Topic Test - Biological Organic](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-7-5-end-of-topic-test-biological-organic.md)
- 6.8 Organic Synthesis (A2 Only)
  - [6.8.1 Organic Synthesis (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-8-1-organic-synthesis-a2-only.md)
  - [6.8.2 Examples of Synthetic Routes (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-8-2-examples-of-synthetic-routes-a2-only.md)
  - [6.8.3 End of Topic Test - Polymers & Organic Synthesis](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-8-3-end-of-topic-test-polymers-and-organic-synthesis.md)
- 6.9 NMR Spectroscopy (A2 Only)
  - [6.9.1 Understanding NMR (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-9-1-understanding-nmr-a2-only.md)
  - [6.9.2 Carbon-13 NMR (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-9-2-carbon-13-nmr-a2-only.md)
  - [6.9.3 Hydrogen-1 NMR (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-9-3-hydrogen-1-nmr-a2-only.md)
  - [6.9.4 Hydrogen-1 NMR 2 (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-9-4-hydrogen-1-nmr-2-a2-only.md)
  - [6.9.5 End of Topic Test - NMR](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-9-5-end-of-topic-test-nmr.md)
- 6.10 Chromatography (A2 Only)
  - [6.10.1 Overview of Chromatography (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-10-1-overview-of-chromatography-a2-only.md)
  - [6.10.2 Thin-Layer Chromatography (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-10-2-thin-layer-chromatography-a2-only.md)
  - [6.10.3 Column Chromatography (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-10-3-column-chromatography-a2-only.md)
  - [6.10.4 Gas Chromatography (A2 Only)](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-10-4-gas-chromatography-a2-only.md)
  - [6.10.5 End of Topic Test - Chromatography](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-10-5-end-of-topic-test-chromatography.md)
- 6.11 A-A* (AO3/4) - Organic 2
  - [6.11.1 A-A* (AO3/4) - Organic 2](https://senecalearning.com/en-gb/revision-notes/a-level/chemistry/aqa/6-11-1-a-a-ao34-organic-2.md)