Chemistry/Equilibrium Titration Prep
Solutions Needed (for one class of 24 students):
Note: Solutions 1 and 2 must be mixed and the precipitate allowed to settle for a few minutes in a stoppered vessel. The solution remaining above the precipitate is 0.100 M Fe(NO3)2. This solution is unstable and MUST be freshly prepared a few minutes before the lab period. Therefore, make up separate 500 mL portions of solutions 1 and 2 for each class. Also, the FeSO4 solution is somewhat unstable and should be made up no more than 1 hr ahead of the time it will be used (store in a closed amber bottle).
Solutions 3 and 4 can be made up in larger amounts, depending on the number of classes.
1. 500 mL of 0.200 M FeSO4 (ferrous sulphate, FeSO4.7H2O, 27.81 g diluted to exactly 500 mL.)
2. 500 mL of 0.200 M Ba(NO3)2 (barium nitrate, Ba(NO3)2, 26.14 g diluted to exactly 500 mL.)
3. 1 L of 0.100 M AgNO3 (silver nitrate, AgNO3, 16.99 g diluted to exactly 1 L. CARE: use gloves to handle the AgNO3.)
4. 2 L of 0.100 M KSCN (potassium thiocyanate, KSCN, 19.44 g diluted to exactly 2 L.)
- After the FeSO4 and Ba(NO3)2 have been mixed and the precipitate has formed, carefully pour off the solution (leaving the solid behind) into 6 small bottles, labeled "Fe(NO3)2".
- Divide the AgNO3 solution among 6 bottles, labeled "AgNO3".
- Divide the KSCN solution among 6 bottles, labeled "KSCN".
- Set out 6 clean and dry 100 mL graduated cylinders, labeled "Fe(NO3)2".
- Set out 6 clean and dry 100 mL graduated cylinders, labeled "AgNO3".
- Burettes (at least 12)
- 25 mL volumetric pipettes (at least 12)
- Rubber stoppers to fit 250 mL erlenmeyer flasks