Formulae and Equations

Writing Chemical Equations A Balance Equation According to the Law of Conservation of Mass, atoms cannot be created or eliminated in the process of chemical reaction. Therefore, the amount of atom of each element before reaction must be equal after reaction. Example:Balance the following chemical equations: Mg +    O2 →    MgO CuO + … Read more

Formula of Molecule In SPM, you need to know the formulae of the following molecules Fluorine  F2 Hydrogen chloride  HCl Chlorine  Cl2 Hydrogen bromide  HBr Bromine  Br2 Hydrogen iodide  HI Iodine  I2 Nitric oxide  NO Carbon dioxide  CO2 Nitrogen dioxide  NO2 water  H2O Nitrous oxide  N2O Ammonia  NH3 Tetrachloromethane  CCl4 Sulphur trioxide  SO3 Hydrogen sulphide … Read more

Chemical Formlula of Ionic Compounds 2 Requirements to form the formula of an ionic compound Have at least 2 types of ions that contain opposite charge. The amount of positive charge/charges must be equal to the amount of negative charge/charges in the compound. Example 1 – If the Charge of the Positive Ions = Charge … Read more

Formula of Ions Ionic compounds made up of positive ions and negative ions. To write the formula of an ionic compound, we need to know the symbol and charge of the ions in the compound. Positive ions that you need to know in SPM form 4 chemistry: Ion Symbol Ion Symbol Potassium K+ Calcium Ca2+ … Read more

Percentage of Composition of a Compound To find the percentage of composition of a substance means to find the percentage of mass of each element in the molecule of the substance to the mass of the molecule. The percentage of mass of an element can be determined by the following equation: RAM = Relative atomic … Read more

Molecular Formula The molecular formula of a substance is the chemical formula that gives the actual number of atoms of each element in the substance. A molecular formula is the same as or a multiple of the empirical formula.  For example, the empirical of carbon dioxide is CO2 and the molecular formula is also CO2. Whereas, … Read more

Empirical Formula The empirical formula of a substance is the chemical formula that gives the simplest whole-number ratio of atoms of each element in the substance. Empirical = information gained by means of observation, experience, or experiment. Example: Chemical Substances Molecular Formula Empirical Formula Glucose C6H12O6 CH2O Water H2O H2O Carbon Dioxide CO2 CO2 Benzene … Read more

Each element is represented by its own chemical symbol. In an element, the chemical formula represents the atoms in the molecule. The chemical formula tells us: the types of atoms or ions in the compound, the number of atoms or ions in the compound, For example, the chemical formula for ethene is C2H4. This shows … Read more

Molar Volume of Gas Equal amount of gas occupies same volume of space. Molar volume of a gas is defined as the volume occupied by one mol the gas at certain condition At room temperature(25ºC) and pressure (1 atm), one mole of any gas occupies a volume of 24 dm³ (24 000 cm³ ) At … Read more

Sometime, you may be given the mass of a substance, and asked to find the number of particles (or vice versa). To solve the problem, we must find the number of mole of the substance then only we can find the number of particles (or mass of the substance). Example: How many molecules are there … Read more