Category: Grade 11

 

Determining the Concentration of Oxalic Acid Hydrate Solution 

  

Introduction: 

In this lab, we will determine the concentration of an oxalic acid hydrate solution through a titration process. Oxalic acid is a diprotic acid that forms a hydrate compound with water molecules. By titrating the solution with sodium hydroxide (NaOH) solution, we can determine the concentration of oxalic acid hydrate. 

  

Materials: 

1. Oxalic acid hydrate (C2H2O4·nH2O) – 0.4 g 
2. Unknown base – 10 mL
3. Phenolphthalein indicator solution
4. Burette
5. Pipette
6. Beakers
7. Flask
8. H2O 100 mL
9. Graduated cylinder
10. Magnetic stirrer
11. Safety goggles

 

Procedure: 

  

1. Safety Precautions:

   – Put on safety goggles throughout the experiment. 

   – Handle all chemicals with caution and avoid contact with eyes or skin. 

   – Be careful walking around when bringing chemicals to your station (be aware of your surroundings) 

2. Preparation of Oxalic Acid Hydrate Solution: 

Weigh 0.4 g of oxalic acid hydrate (C2H2O4·H2O).  

Dissolve the weighed oxalic acid in 100mL of H2O to make a solution with the concentration of 0.04  

Make sure to weigh the 100 mL of H2O  in a beaker 

Stir the solution until the compound is completely dissolved. 

Note the volume and calculate the molarity (concentration) of the oxalic acid hydrate solution. 

   

3. 3. Titration Procedure:

   – Rinse a burette with a small amount of unknown base, making sure it is filled with the solution. 

   – Using a pipette, measure 10 mL of the prepared oxalic acid hydrate solution into a clean flask. 

   – To do this add a small amount of acid and roll in around the flask to clean it. 

   – Add a few drops of phenolphthalein indicator to the flask. 

   – Place the flask on a white tile or a piece of white paper to easily observe color changes. 

   – Start the titration by adding base drop by drop into the conical flask while swirling the flask gently. 

   – Continue adding the unknown base until a permanent pink color is obtained, indicating the completion of the reaction. 

   – Note the volume of unknown base used. 

 

Table: 

	Trial 1	Trial 2	Trial 3
How many mL are in the burette	40 ml of unknown base	27.5 mL	34.5 mL
Final reading of the burette	27.5 ml	44.9 mL	51.8
Amount of acid used	10 mL	10 ml	10 mL
Volume of  base  used	12.5 mL	17.9 mL	17.3 mL
Amount of phenolphthalein indicator solution drops used	3 drops	4 drops	4 drops
Average volume of base in mL	15.9 mL

  

  

4. 4. Repeat:

   – Repeat the entire titration procedure two more times to obtain a reliable average value for the concentration of oxalic acid hydrate. 

0.4g C2H204 (2H2O) × 1 mol ÷ 126g = 0.00317 mol ÷ 0.100L = 0.03 

• Identifying The Base Lab  
• • Bunsen burner 
• Materials: 
• • Q-tips 
  • Flint striker 
  • Tweezers 
  • Beaker 
  • 20mL of unknown solution

  Safety Procedure: 

  • Always wear safety glasses 
  • Tie up hair and roll up sleaves if necessary  

  Preparation:  

  • Set up Bunsen burner on a empty countertop and connect it to the gas. 

  • Turn on gas. 
  • Light burne4r with flint striker 
  • Make the flame your desired height.  

  Actual Identification Process:  

  • Take a Q-tip and dip it in the dissolved acid that’s in the beaker. 

  • Carefully use the tweezers to pick up the Q-tip and hold it over the flame. 
  • Once it starts burning identify and record the colour the flame changes to

  • 
  • • 20mL of unknown solution with Q-tips over Bunsen burner 
  • Notes: 
  • • The flame had turned orange/red (brick red) which means it is Calcium

 

pictures during