Quantitative Chemistry: Keywords

actual yield

The amount of product actually produced by a reaction.

atom economy

The measure of the amount of starting materials that end up as useful products.

Avogadro constant

The number of atoms, molecules or ions in a mole of a given substance.

Avogadro’s law

Equal amounts in moles of gases occupy the same volume under the same conditions of temperature and pressure.

concentration

The amount of substance (e.g. the mass) in a certain volume of a solution.

conservation of mass

This law states that no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants.

limiting reactant

The reactant that is completely used up since it limits the amount of products formed.

mole

Chemical amounts are measured in this. The - is the unit for amount of substance. The symbol for the unit - is mol.

percentage by mass

• A value representing the concentration of an element in a compound or a component in a mixture.

• It is calculated by the mass of a component divided by the total mass of the mixture, multiplied by 100.

percentage yield

The percentage ratio of the actual yield of product from a reaction compared with the theoretical yield.

relative formula mass

The sum of the relative atomic masses of the atoms in the numbers shown in the formula. It is numerically equal to the mass of one mole of a substance in grams.

theoretical yield

The maximum amount of product that could be produced from the given reactants, assuming a complete reaction takes place.

thermal decomposition

The reaction that occurs when heat is applied to a compound causing it to break down into its different chemical constituents.

uncertainty

• All measurements have a degree of this regardless of precision and accuracy.

• Can be due to the limitations of the measuring equipment or due to the skill of the experimenter carrying out the measurements.