quantitive chemistry-unit3

• what is the percentage mass of an element in a compound equation

  percentage mass=( Ar x number of atoms of that element/Mr of the compound) x100
• what is avogadros constant

  6.02 x 10 (power of 23)
• what is one mole equal to

  6.02 x 10 (power of 23)
• what is the formula yo find the number of moles

  number of moles = mass in g/Mr
• mass is always ? in a chemical reaction

  conserved
• what is one explanation to why as mass would change in a chemical reaction

  -if the mass increases it’s because one of the reactants is a gas that’s found in the air and all the products are solids, liquids or aqueous
• what is another explanation as to why the mass changes in a chemical

  -if the mass decreases, one of the products is a gas and all the reactants are solid, liquid or aqueous
• when do réactions stop

  when one reactant is used up
• when one reactant is fully used up what are the other reactants left

  in excess
• what is the reactant that is used up in a reaction called and why

  limiting reactant, limits the amount of product that’s formed
• what is the equation for concentration

  concentration = mass of solute/volume of solvent
• what is concentration measured in

  g/dm(power of 3)