Chapter 3 - Quantitive Chemistry

• Define Relative Atomic Mass and Relative Formula mass

  RAM - Average mass of atoms in an element taking into account of masses and abundance of its isotopes

  RFM - sum of RAM's of all atoms in the formula
• What is Avogadro's constant?

  Number of atoms, molecules or ions in a mole of a given substance

  • 6.02 x 10 ²³
• State the formula that links molecular mass and moles together

  Mass = Mr x Moles

  
• What is a Limiting Reactant

  A reactant which limits the amount of products as it gets completely used up.
• Formulae which links concentration, mole/mass and volume.

  Concentration (g per dm³) = Mass (g)/Volume (dm³)

  Concentration (mol per dm³) = moles of solute /volume (dm³)
• Why is if not always possible to obtain the theoretical amount of products in a chemical reaction?

  • The mixture may not go to completion becuause it is reversible
  • Some of the product may be lost when it is separated from the reaction mixture
  • Some of the reactants may react in ways different to expected reaction (side reactions make occur)
• How is the % yield of a product in a chemical reaction?

  % Yield = actual mass of product x 100 ÷ maximum theoretical mass of product
• How can you convert a volume reading in cm³ to dm³?

  divide by 1000