Tag: a level chemistry

Reversible Reactions, Equilibrium, and Le Chatelier’s Principle

Infographic on equilibrium and Le Chatelier's principle. Equilibrium is reached when a reaction's forwards and backwards rates are equal. Le Chatelier's principle states that when a change is made to the conditions of a dynamic equilibrium the system counteracts the change, changing the quantities of reactants and products. Increasing concentration of substances on one side of the reaction will increase the concentrations of substances on the other side. Increasing temperature favours the endothermic reaction, while decreasing it favours the exothermic reaction. And increasing pressure favours the side of the reaction with fewer gas molecules.
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When you think of chemical reactions, you might think of them as irreversible, permanently changing one substance into another. While this is true in some cases, some chemical reactions are reversible, and we can take the products of the reaction and turn them back into the reactants. These reversible reactions can, under certain conditions, reach what we call ‘equilibrium’. Equilibrium can be a tricky concept to understand, but this graphic tries to make it a little clearer.

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VSEPR & Shapes of Molecules

VSEPR & Shapes of Molecules

VSEPR & Shapes of Molecules
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One for the chemistry students (and teachers!) out there today, with a look at how we can work out the shapes of some simple molecules using Valence Shell Electron Pair Repulsion (VSEPR) theory. These shapes are decided by the arrangement of electrons around the central atom in the molecule.

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