Calculations

Question 1

Relative atomic mass calculation

Answer 1

Multiply each relative isotopic mass by its abundance and add them up
Divide by total abundance

Question 2

Ar definition

Answer 2

Relative atomic mass

Question 3

Relative formula mass calculation

Answer 3

Find Ar of all atoms present

Add up all relative atomic masses

Question 4

Mr definition

Answer 4

Relative formula mass

Equal to mass in gram per mole

Question 5

Empirical formula definition

Answer 5

Simplest ratio of atoms

Question 6

Mole definition

Answer 6

Number of particles equal Avogadro’s constant
6.02 x 10^23
one mole of atom or molecule will have same mass as its relative particle mass

Question 7

Number of atoms in a number of moles calculation

Answer 7

Multiply Avogadro’s constant by number of moles of each atom present

Question 8

Number of moles formula

Answer 8

Mass in grams of element / Mr of compound or Ar of element

Question 9

Concentration formula

Answer 9

Concentration (g dm^-3) = Mass of solute(g) / volume of solution (dm^3)

Question 10

Empirical formula calculation from masses

Answer 10

Work out moles of each element

Work out smallest ratio between moles of each element