Equations

Question 1

Relative formula mass (Mr)

Answer 1

sum of relative atomic masses of atoms in the molecule

Question 2

Relative atomic mass = (Ar)

Answer 2

sum of (mass of isotope x isotope abundance)/100

Question 3

Percentage by mass of an element in a compound

Answer 3

((Aᵣ x number of atoms of the element)/Mᵣ of the compound) x 100

Question 4

uncertainty of a set of repeated measurements

Answer 4

±range of measurements/2

Question 5

uncertainty of a measuring instrument

Answer 5

±smallest scale division/2

Question 6

Percentage yield

Answer 6

actual yield/ theoretical yield

Question 7

Atom economy (%)

Answer 7

Aᵣ of desired product/ Sum of Aᵣ of reactants

Question 8

Concentration - mass

Answer 8

mass/volume

Question 9

Concentration - moles

Answer 9

number of moles/volume

Question 10

Number of moles

Answer 10

Mass/Mr or Ar

Question 11

Volume of gas (at room temperature)

Answer 11

number of moles x 24

Question 12

Overall energy change

Answer 12

energy used to break bonds - energy released from making new bonds

Question 13

Mean rate of reaction

Answer 13

Quantity of reactant used or product formed/ time taken

Question 14

Rᵣ value

Answer 14

distance moved by substance/distance moved by solvent