CH1 - Chemical calculations

Add the Ar of each element together

The mass of each different isotope of the element

The relative abundance of each isotope of the element

Ionisation - sample is bombarded with high energy electrons, knocking electrons off to form positive ions

Acceleration - electric field accelerates the positive ions to a high speed

Deflection - different ions are deflected by the magnetic field according to mass/charge ratio

Detection - beams of ions passing through the machine are detected electrically. Ions with correcty mass/charge ratio pass through. Signal is amplified and recorded.

amount in moles (n) = mass (m)/molar mass(M)

Identifying unknown compounds

Identifying trace compounds

Analysing molecules in space

Find amount in moles of each element present 

Find the ratio of number of atoms present (divide by smallest number from step 1)

Convert numbers into whole numbers

Find the mass of empirical formula 

Divide molecular mass by value of step 1

Multiply empirical formula by value of step 2

Multiply the number of moles by 22.4dm^3 (in most cases this is what 1 mole of a gas occupies)

At a constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure.

V ∝ 1/P

The volume of a fixed mass of a given gas, at constant pressure, is directly proportional to its temperature in kelvins.

V ∝ T

Equal volumes of different gases, measured at the same temperature and pressure, contain the same number of molecules.

V ∝ n

PV = nRT

(rearranged accordingly) 

P = pressure (Pa)

V = volume (m^3) 

n = moles

R = gas constant (8.31 J K-1 mol-1)

T = temperature (K)

Concentration = amount of moles of solutie / volume of solution

c = n/V

atom economy = (mass of required product/total mass of reactants) x 100%

percentage yield = (mass of product obtained/maximum theoretic yield) x 100%