C3-quantitative chemistry

• what is the relative formula mass?

  the relative atomic masses added together
• how to find the percentage mass of an element in a compund?

  (Ar x number of atoms in the element / Mr of compound) x 100
• what is a mole?

  amount of a substance
• what is avagadros constant?

  6.02 x 10^23
• how to find number of moles?

  mass / Mr
• how is mass conserved?

  no atoms are created or destroyed so no mass is lost or gained
• how to know if mass is conserved?

  total Mr of reactants should equal total Mr of products
• how to balance equations using reacting masses?

  -divide mass of each substance by the relative formula mass to get number of moles

  -divide number of moles of each substance by the smallest number of moles in reaction

  -make all numbers whole

  -write balanced symbol equation
• how to find the mass of product formed?

  -write balanced equation

  -work out relative formula masses for what you want

  -find out the moles of the substances you know the mass of

  -use balanced equation to find how many moles there will be of the other substance

  -use number of moles to calculate the mass
• what is the concentration?

  the amount of a substance in a certain volume of a solution
• how to find the concentration?

  mass / volume