A-Level Chemistry revision notes

A-Level (A2/AS) Chemistry revision notes providing information and assistance across all examination boards including AQA, CIE, OCR, Edexcel, Eduqas & WJEC. Chemistry is a complicated A-Level with a lot of content and information to work through. We have put together some of the best revision notes and learning materials to hopefully make sitting your Chemistry A-Levels a little bit easier and stress-free.

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High resolution mass spectrometry (HRMS)

Summary Mass spectrometry (MS) is an analytical technique used to identify an unknown organic compound. MS spectrum gives us peak mass to charge (m/z) ratio for a compound. Low resolution MS gives us m/z to a two decimal digits and may not be enough to distinguish between two molecules having same molecular mass (at two ...

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Collision Theory

The study of kinetics enables scientists to determine the relationship between the changes in conditions and the speed of a particular chemical reaction. One of the most important factors that affect the speed of a reaction is the reactivity of chemicals involved in that specific reaction. Furthermore, there are several variables that can also impact ...

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Factors Affecting the Rate of a Reaction

In every chemical reaction, the concentration of reactants (starting compounds) and those of the products (resulting compounds) change as time passes by. The measure of the change in the concentration of the reactants or products per time unit is referred to as the reaction rate for a particular chemical reaction. The reaction rate is defined as the speed with ...

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Le Chatelier’s Principle

Le Chatelier’s Principle is used for qualitative predictions of how a chemical system will respond to an alteration of its equilibrium conditions by means of change in temperature, pressure, or concentration of reactants and products.  The concept of this principle is closely related to the idea of chemical equilibria and equilibrium constants. Therefore, you must ...

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Dynamic Equilibrium

As you may already know, the concentration of reactants decreases while the concentration of products increases as a given reaction proceeds.  But are the changes in the concentration of reactants and products continuous? After a while, the concentrations of reactants and products no longer change, meaning that the reaction has reached the state referred to ...

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Equilibrium Constants

To understand what equilibrium constants are, let's start at the beginning. Chemical equilibrium is the state that indicates that the concentrations of reactants and products no longer change in a reaction. When a chemical equilibrium is a result of two active and opposing reactions, the equilibrium that is reached by the system is called a ...

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Reactions of Alkyl Halides

Summary Alkyl halides are organic compounds containing carbon – halogen bond. The polarizability of carbon – halogen bond greatly influences the chemical reactivity of alkyl halides. Alkyl halides undergo nucleophilic substitution reaction. Substitution reaction can follow SN1 or SN2 mechanisms.  Both mechanisms follow different conditions and offer different products. Alkyl halides also form an important ...

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Role of chloroalkanes in Ozone Layer depletion

Summary Chloroalkanes are organic compounds containing carbon and chlorine atoms.  These organic compounds pose serious threat to our planet. They are responsible for ozone depletion. The chemical reaction for ozone depletion is catalyzed by UV radiations. Comprehensive efforts are in place now to combat emission of these chloroalkanes The Montreal protocol has been a great ...

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Reactions of Alkenes

Summary Alkenes are unsaturated organic compounds containing carbon – carbon double bonds. They are important feedstock for series of industrial chemicals specially polymers.  Simple examples are ethene and propene that are important industrial organic chemicals. The chemical activity of alkenes are mainly because of carbon – carbon double bond, Alkenes undergo addition reactions at site ...

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Reactions of Alkanes

Summary Alkanes are saturated hydrocarbons. Methane is a simple example of alkanes They show low chemical reactivity due to saturation compared to alkenes or alkynes. The halogenation of alkanes forms haloalkanes via free radical reaction mechanism. Halogenation reaction involves three steps, initiation, propagation & termination. Different halogens exhibit different activity for alkanes due to their ...

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