Amount of substance

Question 1

Atom economy

Answer 1

The measure of the amount of starting materials that end up as useful products
Equation:
percentage atom economy = molecular mass of desired product / sum of molecular masses of all reactants x 100

Question 2

Avogadro’s constant

Answer 2

The number of atoms, molecules or ions in one mole of a given substance (6.022 x 10 23)

Question 3

Concentration

Answer 3

The amount of substance per unit volume. Units given in g/dm3 or mol/dm3

Question 4

Empirical formula

Answer 4

The smallest whole number ratio of atoms of each element in a compound

Question 5

Limiting reactant

Answer 5

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

Question 6

Mole

Answer 6

The mass of a substance containing the same number of units as there are atoms in exactly 12g of carbon-12

Question 7

Molecular formula

Answer 7

The actual ratio of atoms of each element present in a compound

Question 8

Percentage by mass

Answer 8

A value representing the concentration of an element in a compound or a component of mixture.
Equation:
percentage by mass = mass of desired component / total mass of mixture x 100

Question 9

Percentage yield

Answer 9

The percentage ratio of the actual yield of product from a reaction compared with the theoretical yield.
Equation:
percentage yield = actual yield / theoretical yield x 100

Question 10

Relative atomic mass

Answer 10

The average mass of an atom of an element compared to 1/12th the mass of an atom of carbon-12

Question 11

Relative molecular mass

Answer 11

The average mass of one molecule of an element or compound compared to 1/12th the mass of an atom of carbon-12