quantitative chemistry

• what is the conservation of mass?


  in a chemical reaction total mass of products = total mass of reactants
• when a gas is a reactant why does the mass of the products appear to be more than the reactants?


  atoms from the gas have been combined into the product
• when a gas is a product why does the mass of the products appear appear to be less than the reactants?

  the gas product is allowed to escape and its mass is not measured
• what is relative formula mass?

  the sum of the relative atomic masses of each atom in a compound
• what are the four state symbols and what to they stand for?

  1. (s)= solid
  2. (l)= liquid
  3. (g)= gas
  4. (aq)= aqueous
• what symbol do we use for relative formula mass?

  Mr
• what is a mole?

  avogadro's number of particles
• what is avogadro's number?

  $6.02\times10^{23}$
• what formula relates mass, moles and Mr?

  moles = mass/Mr
• what is a limiting reactant?

  the reactant that is completely used up in a chemical reaction
• what is the unit for concentration?

  $g/dm^3$
• how do you convert between cm3 and dm3?

  cm3>dm3 divide by 1000
• what formula relates concentration, mass and volume?

  concentration = mass/volume