Topic 3 - Quantitative Chemistry

• Mole (mol)


  A measure of the number of particles (atoms, ions or molecules) contained in a substance
• One mole of any substance (element or compound) contains the same number of particles - six hundred thousand billion billion or 6.02x10^23
• Avogadro constant


  The value of 6.02x10^23 particles per mole
• Relative atomic mass or relative formula mass


  The mass of one mole of a substance in grams
• One mole of sodium atoms contains 6.02 x 10^23 atoms
• The relative atomic mass of sodium is 23.0
• One mole of sodium atoms has a mass of 23.0g
• Calculating the amount of substance (number of moles)

  mass of substance (g) / atomic (or formula) mass (g/mol)
• Balanced equations show the number of moles of each product and reactant
• Balanced equations can be used to calculate the mass of the reactants and products
• Balancing an equation


  Calculate the numbers needed to balance the equation from the masses of the reactants and products
• Balancing an equation using moles


  Calculate the amount (moles) of each reactant and product

  2. Use the mole ratios to write the balanced equation
• Limiting reactant


  The reactant that is completely used up in a chemical reaction, stopping the reaction from going further
• Excess reactant


  The reactant that is not used up in a chemical reaction
• Moles of a gas

  At room temperature and pressure, one mole of any gas takes up a volume of 24dm³
• Calculating the volume of a gas

  volume = amount (mol) x 24dm³
• what equation links number of moles, concentration and volume?

  number of moles= concentration x volume
• What equation links mass, molar mass and number of moles? 


  Mass = Mr x number of moles