Fundamental Ideas 2 0.0 / 5 ? ChemistryFundamental Ideas 2IGCSEAQA Created by: elkamoogs xdCreated on: 12-12-15 11:08 Relative Atomic Mass definition The average mass of an atom compared with the mass of an atom of Carbon-12. 1 of 11 Relative Molecular Mass definition The sum of the relative atomic masses of the atoms making up a molecule. 2 of 11 Relative Formula Mass definition The sum of the relative atomic masses of the atoms making up a compound containing ions. 3 of 11 Mole definition 1 mole is the amount of a substance which is made up of the same number of particles as there are carbon atoms in 12g of carbon-12. 4 of 11 What is the Avogadro number? 6.02 x 10^23, this is the number of carbon atoms in 12g of carbon-12. 5 of 11 How to find the number of moles in a substance Number of moles = mass (g) / mass of 1 mole (molecular mass) 6 of 11 Empirical formula definition The simplest whole number ratio of atoms in a substance. 7 of 11 Percentage composition definition The percentage of a substance made up by one element. 8 of 11 How to find percentage composition Mass of element you want / molecular mass of whole molecule * 100 9 of 11 How to calculate percentage yield Actual yield / theoretical yield * 100 10 of 11 3 reasons theoretical yield not obtained Reaction could be reversible, some product may be lost, some of the reactants might react differently to expected. 11 of 11
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