## Mass spectrometry (AS and A2 analytical techniques)

This topic overlaps organic analysis for AS and A2. High resolution mass spectrometry can be used to determine the molecular formula of a compound from the accurate mass of the molecular ion. Understand that the fragmentation of a molecular ion: M+• → X+ + Y• gives rise to a characteristic relative abundance spectrum that may give information about the structure of

## Balanced equations and associated calculations

But, as total mass of products=total mass of reactants [Law of conservation of mass], then Assessment and practical opportunities • write balanced equations (full and ionic) for reactions studied • balance equations for unfamiliar reactions when reactants and products are specified. Students should be able to use balanced equations to determine: • masses • reacting volumes of gases • percentage yields •

## Empirical and molecular formula

Empirical formula is the simplest whole number ratio of atoms of each element in a compound. Molecular formula is the actual number of atoms of each element in a compound. The relationship between empirical formula and molecular formula. Assessment and practical activities Students should be able to: • calculate empirical formula from data giving composition by mass or percentage by mass • calculate molecular

## The ideal gas equation

The ideal gas equation pV = nRT with the variables in SI units. [Students will not be expected to recall the value of the gas constant, R] Assessment and practical skills Students could be asked to find the Mr of a volatile liquid. Students understand that the correct units need to be in pV = nRT . Students carry out calculations with the ideal gas equation,