quantitive chemistry

• Law of Conservation of Mass

  Matter is not created or destroyed
• Relative formula mass of a compound

  Sum of the RFMs of the elements

  
• Why do some reactions appear to involve a change in mass?

  A reactant/product is agas

  
• The mass(g) of 1 mole of a substance is equal to ...

  Mass of 1 mole =Relative Formula Mass(eg 1 mole of oxygen = 16g)
• What is a mole?

  6.02 x 10²³

  
• Mole equation

  Moles (mol) = Mass (g) / RFM

  
• What is a limiting reactant?

  the reactant thatruns out firstin a reaction,limiting amountofproduct
• Concentration equation

  Concentration(g/cm³) = Mass(g) / Volume(cm³)

  
• Solute:Volume ratio in High concentrations

  High solute, Low volume
• Solute:Volume ratio in Low concentrations

  Low solute, High volume
• What is percentage yield?

  how muchproductisactually madein a reaction
• Percentage yield equation

  Actual yield / Theoretical yield x 100

  
• Why is it not always possible to obtain the theoretical amount of product?

  -Reversible reactionmay not go tocompletion-Product may be lostwhen it isseparatedfrom thereaction mixture- Some reactants mayreact in different ways(side reactions)
• What is atom economy?

  amount ofreactantsthat end up asuseful products
• Atom economy equation

  RFM ofdesired products/ RFM ofall reactantsx 100

  
• Why is it important to consider atom economy?

  - raw materials areexpensive- waste isexpensive to dispose- can beless sustainableto use lots of reactants for little product
• Reasons a reaction pathway may/may not be chosen

  - yield

  - rate of reaction

  - equilibrium position

  - usefulness of by products
• What is concentration measured in?

  g/dm³ or mol/dm³
• How do you convert cm to dm?

  divide by 1000 (1 cm = 0.001 dm)
• Equation for Concentration of a solution

  Concentration (g/dm³) = Moles(mol) / Volume (dm3)

  
• Would 1 mole of CO₂ and 1 mole CH₄ take up the same or different volumes?

  the same -equal amounts of gases(in moles)occupy the same volumeunder the same conditions
• What is volume measured in?

  dm³

  
• What is the volume of 1 mole of any gas at room temperature and pressure?

  24dm³
• Volume of gas equation

  Volume(dm³) = Moles x 24