Chemical Reactions and Equations
Frequently Asked Questions
A chemical reaction is a process in which one or more substances change to form new substances with new properties.
A chemical equation is a symbolic representation of a chemical reaction using formulas of reactants and products.
Equations are balanced to satisfy the Law of Conservation of Mass, ensuring equal atoms on both sides.
Reactants are starting substances, and products are the new substances formed in a chemical reaction.
A balanced equation has equal numbers of each type of atom on both sides of the reaction.
It shows the correct formulas of reactants and products but is not balanced.
Common symbols: (s) solid, (l) liquid, (g) gas, (aq) aqueous solution.
A combination reaction occurs when two or more reactants combine to form a single product.
The reaction of hydrogen and oxygen forming water (H2 + ½O2 ? H2O).
A reaction in which a single compound breaks down into two or more simpler substances.
Heating of calcium carbonate gives CaO and CO2 (CaCO3 ? CaO + CO2).
A single element replaces another element from its compound in a reaction.
Two compounds exchange ions to form two new compounds.
Precipitation is a type of double displacement reaction forming an insoluble solid.
Oxidation is the addition of oxygen or removal of hydrogen during a reaction.
Reduction is the removal of oxygen or addition of hydrogen in a reaction.
A redox reaction involves both oxidation and reduction occurring simultaneously.
Corrosion is the gradual destruction of metals by chemical reaction with the environment, such as rusting of iron.
Rusting can be prevented by painting, oiling, galvanizing, or coating with non-reactive metals.
Galvanization is coating iron with zinc to prevent rusting.
Rancidity is the oxidation of oils and fats in food resulting in foul smell and taste.
By using antioxidants, keeping food in airtight containers, or refrigeration.
It states that mass can neither be created nor destroyed in a chemical reaction.
Magnesium reacts with oxygen forming magnesium oxide and releases energy as light and heat.
It is a decomposition reaction where water splits into hydrogen and oxygen gases.
Iron displaces copper forming ferrous sulphate and copper (Fe + CuSO4 ? FeSO4 + Cu).
It is a single displacement reaction.
A reaction that occurs in presence of light energy, such as photosynthesis.
A reaction that releases energy in the form of heat or light.
A reaction that absorbs energy from its surroundings.
Combustion of methane: CH4 + 2O2 ? CO2 + 2H2O + heat.
Decomposition of calcium carbonate: CaCO3 ? CaO + CO2 requires heat.
It is the reaction between an acid and a base forming salt and water.
It is a reaction producing an insoluble product that separates out as precipitate.
Decomposition caused by heating a compound strongly.
It is another term for double displacement reaction where ions exchange partners.
It is called Plaster of Paris (CaSO4·½H2O).
Zn + 2HCl ? ZnCl2 + H2.
It ensures correct reactant proportions to optimize yield and minimize waste.
Respiration releases energy by oxidizing glucose in cells.
It is copper oxide, formed by corrosion of copper metal.
It reacts with sulphur compounds forming black coating of silver sulphide.
Photolytic decomposition.
Rusting of iron and spoiling of food are oxidation processes.
Because oxidation of glucose and reduction of oxygen happen together producing energy.
A catalyst is a substance that increases reaction rate without being consumed.
Decomposition of hydrogen peroxide using manganese dioxide as catalyst.
It is a list of elements ranked by their reactivity to displace other elements.
Neutralization reaction between an acid and a base.
Combination, decomposition, displacement, double displacement, oxidation-reduction reactions.
