AS – Volumetric Analysis 1:
Preparation of a standard solution of sodium Hydroxide
Background information:
A standard solution is any solution in which we know the exact concentration. A standard solution of a solid can be prepared by weighing a mass of the solid, and dissolving it in a known volume of solution in a volumetric flask. Today, you will prepare a standard solution of sodium hydroxide. Since the dissolution process is exothermic, we will be using this solution in a second lab next class.
Materials:
- Vial with around 2 of NaOH
- 100 o 150 mL Beaker
- 250 cm3 volumetric flask
- Glass rod
- Triple beam balance
- Distilled water
Procedures
- Measure the mass of the test tube with the NaOH pellets …………………..g
- Measure the mass of the empty 100 ml beaker .………………….g
- Transfer the pellets from the test tube to the beaker
- Measure the mass of the beaker with the pellets ……………………g
- Measure the mass of the test empty test tube with the stopper …….……………..g
- Calculate the mass of the pellets by difference in both the test tube and the beaker. The mass should be almost the same in both cases!
- Record this mass: Mass of NaOH used .…………………..g
- Dissolve the pellets in the beaker using distilled water.
- Pass the solution to the volumetric flask.
- Rinse the beaker several times to be sure that all the NaOH passed to the volumetric flask
- Fill out the volumetric flask to “near” the 250 cm3 mark. BE SURE THAT YOU DO NOT OVERPASS THE MARK.
- Use a rubber stopper to close the volumetric flask
- Label and save the flask for next lab
Lab Setup (EXPLAIN WHAT YOU DID USING GRAPHS IN THREE OR MORE STEPS)
1) 2) 3)
Post Lab Questions:
- Why do you have to prepare the solution in advance?
- How many grams of NaOH did you use for the solution?
- How many moles of solute were present in the volume prepared?
- How many mL of solution did you prepare?
- Calculate the Molarity of the solution in # moles of NaOH/dm3