# 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(NO_{3})_{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 FeSO_{4} (ferrous sulphate, FeSO_{4}.7H_{2}O, 27.81 g diluted to exactly 500 mL.)

2. 500 mL of 0.200 M Ba(NO_{3})_{2} (barium nitrate, Ba(NO_{3})_{2}, 26.14 g diluted to exactly 500 mL.)

3. 1 L of 0.100 M AgNO_{3} (silver nitrate, AgNO_{3}, 16.99 g diluted to exactly 1 L. **CARE:** use gloves to handle the AgNO_{3}.)

4. 2 L of 0.100 M KSCN (potassium thiocyanate, KSCN, 19.44 g diluted to exactly 2 L.)

**Equipment Needed:**

- After the FeSO
_{4}and Ba(NO_{3})_{2}have been mixed and the precipitate has formed, carefully pour off the solution (leaving the solid behind) into 6 small bottles, labeled "Fe(NO_{3})_{2}". - Divide the AgNO
_{3}solution among 6 bottles, labeled "AgNO_{3}". - Divide the KSCN solution among 6 bottles, labeled "KSCN".
- Set out 6 clean and dry 100 mL graduated cylinders, labeled "Fe(NO
_{3})_{2}". - Set out 6 clean and dry 100 mL graduated cylinders, labeled "AgNO
_{3}". - Burettes (at least 12)
- 25 mL volumetric pipettes (at least 12)
- Rubber stoppers to fit 250 mL erlenmeyer flasks