Combustion is a chemical reaction between a fuel and an oxidizing agent, such as oxygen. The fuel is typically a hydrocarbon, which is composed of carbon and hydrogen atoms. When the fuel is exposed to heat, the bonds between the atoms break, releasing energy and producing carbon dioxide and water as byproducts.
pH is a measure of the acidity or basicity of a solution. It is determined by the concentration of hydrogen ions (H+) in the solution. A solution with a pH below 7 is considered acidic, while a pH above 7 is considered basic. The lower the pH, the higher the concentration of H+ ions and the more acidic the solution is. The opposite is true for basic solutions, where a higher pH indicates a lower concentration of H+ ions.
A battery converts chemical energy into electrical energy through a redox reaction, which involves the transfer of electrons from one substance to another. The battery contains two electrodes, one made of a metal and the other of a metal oxide. When the battery is connected to a circuit, the metal oxide electrode loses electrons and the metal electrode gains them, creating a flow of electricity.
An element is a pure substance made up of only one type of atom, while a compound is a substance made up of two or more different elements bonded together. Elements cannot be broken down into simpler substances, but compounds can be broken down into their component elements through chemical reactions.
Enzymes are biological molecules that act as catalysts, meaning they speed up the rate of chemical reactions. They do this by lowering the activation energy required for the reaction to occur. Enzymes have a specific shape that allows them to bind to specific substrates, or reactant molecules, and facilitate the conversion of those substrates into products. Enzymes are not consumed in the reaction, but can be reused for multiple reactions.