3.1.2.1 Relative atomic mass and relative molecular mass & 3.1.2.2 The mole and the Avogadro constant

What is relative atomic/ molecular mass? (1 D.P. always)

Relative atomic mass is the weighted average mass of all isotopes of an element relative to 1/12 of the mass of one atom of carbon-12.

What is the definition of a mole?

The mole is the amount of substance in grams that has the same number of particles as there are atoms in 12 grams of carbon-12

What is the equation for calculating moles from mass?

moles = mass / Mr (molar mass).

What is the equation for calculating moles from concentration and volume?

moles = molar concentration x volume.

How do you convert concentration from mol dm-3 to g dm-3?

Multiply by the molar mass (Mr) of the substance.

What is the equation for calculating number of particles?

No of particles = moles of substance (in mol) XAvogadro'sconstant

What is the formula for density?

Density = mass / volume.

What is the significance of significant figures in calculations?

Answers should be given to the same number of significant figures as the data provided in the question.

4 s.f. in working out

3 s.f. in answer if question says ‘answer to appropriate precision’, otherwise use lowest number of s.f. in question