Formula mass and conservation of mass

4 lessons in Quantitative chemistry.

20 exam questions · 37 marks

3.1 Conservation of mass Why mass is conserved in chemical reactions, how this links to balanced equations, and why the mass seems to change in open systems when a gas is given off or taken in. AQA Edexcel OCR 5 questions 3.2 Relative formula mass and percentage by mass How to calculate the relative formula mass of a substance from relative atomic masses, including formulae with brackets, and how to calculate the percentage by mass of an element in a compound. AQA Edexcel OCR 5 questions 3.3 Empirical formulae How to work out an empirical formula from reacting masses or percentage composition, how to find a molecular formula from the empirical formula and Mr, and the magnesium oxide experiment. Edexcel OCR 5 questions 3.4 Measurements and uncertainty How to find the mean of repeat measurements, identify anomalous results, estimate uncertainty from the range, and understand resolution, accuracy and precision. AQA 5 questions