C4 Chemical Calculations

Question 1

Relative atomic mass Ar

Answer 1

The average mass of the atoms of an element compared with carbon-12 (which is given a mass of exactly 12). Average mass must take into account the proportions of the naturally occurring isotopes of the element.

Question 2

Relative formula mass Mr

Answer 2

The total of the relative atomic masses, added up in the ratio shown in the chemical formula, of a substance

Question 3

Mole

Answer 3

The amount of substance in the relative atomic or formula mass of a substance in grams.

Question 4

Avogadro constant (Avogadro’s number)

Answer 4

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

Question 5

Limiting reactant

Answer 5

The reactant that is used up first in a reaction

Question 6

Yield

Answer 6

The mass of product produced in a chemical reaction

Question 7

Percentage yield

Answer 7

How much product is made in a chemical reaction compared with the maximum amount that could be made (100%)

Question 8

Concentration (of a solution)

Answer 8

The mass of solute dissolve in a certain volume of a solvent, usually expressed in g/dm3

Question 9

Titration

Answer 9

A method for measuring the volumes of two solutions that react together.

Question 10

End point

Answer 10

The point in a titration where the reaction is complete and the titration should stop.