IMPORTANT INFORMATION ABOUT CHEMICAL AMOUNTS.

PRINCIPLES

Answering the question 'how much' is central to both chemical analysis and chemical synthesis. The purpose of qualitative analysis is to answer question 'how much'? by determining the quantities of chemicals in a sample. In advanced chemistry by main method of quantitative analysis is a transition. Titrations provide a precise way to determine the concentration of solution and to investigate the quantities of chemical involved in reactions.

Chemicals also have to answer the question 'how much?' to decide on the quantities of each reactant mixture and to predict the expected yield of product from a chemical synthesis.

CHEMICAL AMOUNTS

When answering the question 'how much?', chemists need to measure amounts of chemical which equal numbers of atoms, molecules or ions. The unit of chemical is the mole. One mole is the amount of substances that contains as many specified atoms, molecules or ions as are atoms in exactly 12 g of carbon-12.

The key to working with chemical amounts in moles is to know the relative masses of atoms on the carbon-12 scale.

The molar mass of an element is numerically equal to the relative mass of element. The relative mass of carbon is 12. The molar mass of an carbon atoms is ( 12 g ^mol).

The molar masses of an element or compound is found by adding up the molar masses of the elements in the given formula. The formula of sulfuric acid is H2SO4. Its molar mass;

= (2 *1 g ^ mol) + (1 * 32g ^ mol) + (4*16g ^ mol)

= 98g^mol.

NOTE: Every physical quantity in science has a name, a symbol and a unit. In the case of amount of substances the name of the unit is 'mole' the symbol is 'n' and the unit is 'mol'.