Amount of substance

• Relative atomic mass (Ar) is the mean mass of an element divided by 1/12 th of the mean mass of an atom of the carbon - 12 isotope.
• Relative molecular mass (Mr) is the mean mass of a compound divided by 1/12 th of the mean mass of an atom of the carbon - 12 isotope.
• The mole is a unit of measurement and one mole is 6.022 x10 ^23.
• The Avogadro constant is the number in one mole of something, and the number of particles can be found by multiplying the Avogadro constant by the number of moles.
• Moles can be found from a substances mass by dividing mass by Mr, and from a substances volume by multiplying volume by concentration.
• The ideal gas equation describes how gases behave under standard conditions, and is p V = n R T.
• The ideal gas constant, R, is 8.31 J/K mol.
• The molecular formula shows the number of atoms in a molecule.
• The empirical formula is the simplest whole number ratio of atoms of each element in a compound.
• Percentage yield is the amount of product made by a reaction, divided by the maximum amount of product that could be made.
• Atom economy is the ratio of the amount of useful product formed to the amount of reactants used in a reaction.