Chemical Equation

Writing Chemical Equations A Balance Equation According to the Law of Conservation of Mass, atoms cannot be created or eliminated in the process of chemistry 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 + H2 → … Read more

Concept of Mole

A mole is defined as the amount of substance which contains the Avogadro Number of particles. The Avogadro Number (or Avogadro Constant) is defined as the number of atoms in 12 g of the carbon-12 isotope, which is equal to 6.02 x 1023. 1 mole = 6.02 x 1023 Example:1 mol of atoms = 6.02 x … Read more

Modern Medicine

Based on the effect of modern medicine to human body, it can be classified into four different categories namely; Analgesics Antibiotics Psychotherapeutic medicines Hormone and steroid Analgesics are drugs used to relieve pain. Antibiotics are a drug that kill or slow the growth of bacteria.  Psychotherapeutic medicines are the medicine that treats mental illness.

Food Additive

Food additives are substances added to food to preserve it or improve its flavour and appearance. Some of the commonly used food additives include preservative, colourants, stabilizers and flavouring. The chart below summarise the 4 groups of food additive Effects of Food Addictive on Health Food additive have the following effect on health. Allergy– MSG … Read more

Detergent

A detergent is a compound, or a mixture of compounds, intended to assist cleaning. Detergent are usually made from synthetic subtances. Example of detergents are sodium alkyl sulphate and sodium alkylbenzene sulphonate. The Structure of a Detergent Molecule The basic structure of the detergent molecule is similar in nature to a soaps. It will dissolve … Read more

Soap

Fatty acids are carboxylic acids that contain 4-28 carbon in the molecule. Soap is the sodium or potassium salt of fatty acid. The general formula of soap is RCOO–Na+ or RCOO–K+, where R is an alkyl group that has long carbon chain. Image below shows the general structure of a soup molecule. Image below shows … Read more

Heat of Combustion

Combustion Combustion is a reaction when a substance burns completely in the excess oxygen. Example, combustion of methane in excess of oxygen produces carbon dioxide and water.CH4 + 2O2 → CO2 + 2H2O All fuel combustion are exothermic reactions. Heat of Combustion The Heat of Combustion of a substance is the heat energy released when 1 … Read more

Heat of Neutralization

The heat of neutralisation is the heat energy evolved when an acid reacts with a base, per mole of the acid or base. All measurements are made under standard state conditions. An example of the enthalpy change of neutralisation is the heat change obtained in the reaction between sodium hydroxide and hydrochloric acid. The equation … Read more

Heat of Displacement

Heat of displacement is the energy change when one mole of metal is displaced from its salt solution by a more electropositive metal Displacement reaction occurs when a metal which is situated at a higher position in the electrochemical series displace a metal below it from its salt solution. The heat of displacement is the … Read more

Heat of Precipitation

The heat of precipitation is the energy change when one mole of precipitate is formed from its ion. Precipitation reaction occurs when two solutions containing cations and anions of insoluble salts added together. This reaction is known as the double decomposition reaction and is used to prepare any insoluble salt. The heat of precipitation is … Read more