Quantitative Chemistry

• What’s the conservation of mass?

  No atoms are lost or made during a chemical reaction , the mass of the products = the mass of the reactants
• What’s the relative formula mass?

  Sum of all the relative atomic masses in all the atoms in the molecular formula
• What’s the % mass of ab element in a compound?

  Relative atomic masses x number of atoms in the element divided by relative formula mass x 100
• What’s avagadros constant?

  6.02 x 10^23
• What’s one mole ?

  One mole of a substance is the amount of the substance that contains an avogadros number of particles
• What’s the formula for number of moles?

  Mass in grams / relative formula mass
• Why does mass change?

  1. If mass increases , then he reactants is one of the gases found in the air and all the products are solids, liquids or aqueous
  2. If mass decreases, one of the products is a gas and all the reactants are solids, liquids or aqueous
• What’s a limiting reactant?

  A reactant which is completely used up - limits the amount of products
• What can concentration of a solution be measured in?

  g/dm^3