Monitoring Chemical Reactions

• How is the concentration of a solution measured?


  In moles per given volume of solution, e.g., mol/dm³
• What is the formula to calculate moles of solute in a solution?


  moles = concentration x volume
• What effect does a smaller volume or larger number of moles of solute have on concentration?


  It gives a higher concentration
• What effect does a larger volume or smaller number of moles of solute have on concentration?


  It gives a lower concentration
• What is the technique of titration used for?


  • To measure the volumes of acid and alkali solutions that react with each other
  • Uses a suitable indicator to determine the endpoint
• What are the steps in the titration method?


  1. Add acid to burette and record the volume
  2. Add known volume of alkali to a conical flask with indicator
  3. Place flask on a white tile
  4. Add acid to alkali until endpoint is reached
  5. Calculate the amount of acid added (titre)
  6. Repeat for concordant titres
• What is the volume of 1 dm³ in cm³?


  1000 cm³
• How is the mass of one mole of a substance related to its relative atomic mass?


  One mole of a substance in grams is the same as its relative atomic mass in grams
• What can be determined after carrying out a titration?


  The exact volume of an acid that reacts with the exact volume of an alkali
• How do you calculate the concentration of an alkali if you know the concentration of the acid?


  Calculate moles of acid, use mole ratio, then calculate concentration of alkali
• What is the equation to calculate the volume of gas at RTP?


  Volume (dm³) of gas at RTP = moles x 24
• What is the volume of 1 mole of any gas at RTP?


  24 dm³
• What is the relationship between molar amounts of gases and their volumes under the same conditions?


  Equal amounts in moles of gases occupy the same volume
• How do you calculate the percentage yield of a reaction product?


  Percentage yield = (Amount of product produced / Maximum amount of product possible) x 100
• What does atom economy measure in a reaction?


  It measures the amount of reactants that become useful products
• How do you calculate the atom economy of a reaction?


  Atom economy = (Mr of desired product / Sum of Mr of all reactants) x 100
• What factors should be considered when choosing a reaction pathway to produce a specified product?

  • Atom economy
  • Yield
  • Rate of reaction
  • Equilibrium position
  • Usefulness of by-products
• What is the unit for concentration of a solution?


  mol/dm³
• What happens to concentration if the mass of solute increases while the volume remains constant?


  The concentration increases
• What is the purpose of using a white tile during titration?


  To see the color change clearly
• If you have 10 moles of a gas at RTP, what is its volume?


  $240 \text{ dm}^3$
• If you have 5 moles of a substance with a molar mass of 20 g/mol, what is its mass?


  $100 \text{ g}$