Quantitative analysis

• How do you calculate the concentration of a solutionin mol dm^-3?

  Concentration (mol dm-3) = moles ÷ volume (dm?)

  
• How can you convert concentration in g dm-3 to moldm^-3?


  Concentration(mol dm^-3) = concentration(g dm^=-3) ÷Mr
• Describe how to carry out an acid-alkali titration to

  find the concentration of alkali:

  1. Rinse the pipette with the solution of unknown concentration (alkali). Use

  this pipette to add a known volume of alkali to a conical flask.

  2. Add a few drops of indicator.

  3. Rinse and fill the burette with acid.

  4. Gradually add the acid to the conical flask.

  5. Record the volume in the burette when the indicator changes colour. (Pink to colourless).

  6. Repeat the experiment until you have concordant results.

  7. Use results to calculate a mean titre and the concentration of alkali.
• How do you the concentration of your titration results?


  Calculate the number of moles of the alkali using the known volumeand concentration (moles = concentration x volume).Use the chemical equation to work out the ratio of acid and alkalithat react and hence work out how many mole of acid have reacted.Divide the moles of acid by the volume used in neutralisation to findconcentration.
• What is percentage yield?

  actual yield/theoretical yield * 100. Final unit should be in kg or g
• Why is a reaction usually less than the theoretical yield?

  incomplete reactions, practical losses during the experiment, competing, unwanted reactions (side reactions).
• What is atom economy?

  A reaction forming a desired product.
• What is the formula for atom economy?

  Mr of desired product/Mr of total product * 100.
• Why might one reaction pathway be chosen over another one?

  Higher atom economy.

  Higher yield.

  Faster rate.

  Equilibrium position favours products more.

  By-products are more useful / less harmful.
• What is molar volume?

  The volume occupied by one mole of a gas.
• What is the formula for molar volume?

  Molar volume = Gas Volume / Number of moles

  
• What is the formula for the volume of gasses?

  Volume = Moles * 24