Chemical Reactions

  • Chemical reactions are all about the re-arrangement of atoms which happens when bonds break and new ones form. It results in the formation of new substances.

  • There are different types of chemical reactions including combination/synthesis, decomposition, and displacement reactions, each having their own unique process and products.

  • A combination or synthesis reaction involves two or more substances coming together to form a new substance. An example could be the reaction between hydrogen and oxygen to produce water. The general equation is A+B –> AB.

  • Decomposition, on the other hand, involves a compound breaking down into two or more simpler substances. The electrolysis of water to form hydrogen and oxygen gases is an example. The general equation is AB –> A+B.

  • Displacement reactions involve the switching of places of two elements. In such reactions, a more reactive element displaces a less reactive element from its compound. The displacement of copper in copper sulphate solution by zinc is an example. The general equation is AB+C –> A+BC.

  • Chemical reactions are also classified as exothermic and endothermic. Exothermic reactions release energy in the form of heat like combustion, while endothermic reactions absorb external energy from the surroundings like photosynthesis.

  • The rate of a chemical reaction can be influenced by several factors: concentration of reactions, temperature, surface area and presence of a catalyst.

  • The concentration of reactions impacts the rate significantly as an increase in concentration leads to more effective collisions and thus increases the reaction rate.

  • Higher temperatures generally increase the rate of reaction. This is because most reactions require a minimum amount of energy to occur, and increasing the temperature increases the amount of energy available.

  • Greater surface area of solid reactants increases the rate of reaction because it allows for more reaction sites, increasing the likelyhood of collision between reactants.

  • The presence of a catalyst, a substance that increases the rate of a reaction without being consumed, can greatly increase the rate of reactions.

  • In any chemical reaction, there should be a conservation of mass, meaning the total mass of reactants equals the total mass of the products.

  • Equilibrium in chemical reactions is the state when the rate of the forward reaction equals the rate of the backward reaction, resulting in no net change in the concentration of reactants and products.

  • The Principle of Le Chatelier predicts how changes in conditions affect the position of equilibrium in a reversible reaction. The system will adjust to minimise the change applied.