Determine the exact molarity of Oxalic acid solution Volumetrically

Determine the Exact Molarity of Oxalic Acid Solution Volumetrically

Abstract:

This experiment aims to determine the exact molarity of an oxalic acid solution using standard volumetric analysis. A solution of oxalic acid is titrated against a standard sodium hydroxide (NaOH) solution using phenolphthalein as an indicator. The volume of NaOH used helps in calculating the molarity of the given oxalic acid solution.

Materials Required:

• Oxalic acid solution (unknown molarity)
• Standard NaOH solution (0.1 M)
• Phenolphthalein indicator
• Burette, pipette, conical flask, beaker
• Distilled water, funnel, clamp stand

Procedure:

1. Rinse and fill the burette with standard NaOH solution.
2. Use a pipette to transfer 25 ml of oxalic acid solution into a conical flask.
3. Add 2-3 drops of phenolphthalein indicator to the oxalic acid in the conical flask.
4. Titrate the solution by slowly adding NaOH from the burette while continuously swirling the flask.
5. The endpoint is indicated by a permanent light pink color.
6. Note the volume of NaOH used.
7. Repeat the titration to obtain concordant readings.

Observation Table:

Reading No.	Initial Burette Reading (ml)	Final Burette Reading (ml)	Volume of NaOH Used (ml)
1	0.0	23.8	23.8
2	0.0	24.0	24.0
3	0.0	23.9	23.9

Calculation:

Balanced Equation: (COOH)₂ + 2NaOH → (COONa)₂ + 2H₂O

Given:
Volume of NaOH used (average) = 23.9 ml = 0.0239 L
Molarity of NaOH = 0.1 M
Volume of oxalic acid = 25 ml = 0.025 L

Using the formula:
M₁V₁/n₁ = M₂V₂/n₂
(0.1 × 0.0239) / 2 = M_oxalic × 0.025 / 1
⇒ M_oxalic = (0.1 × 0.0239 × 1) / (2 × 0.025) = 0.0478 M

Result:

The exact molarity of the given oxalic acid solution is 0.0478 M.

Chemical Equations:

(COOH)₂ + 2NaOH → (COONa)₂ + 2H₂O

20 Short Questions:

1. What is molarity?
2. Define titration.
3. What indicator is used in this experiment?
4. Why is phenolphthalein used?
5. What is the color change at the endpoint?
6. What is the standard solution in this experiment?
7. What is the chemical formula of oxalic acid?
8. What is the role of NaOH in this titration?
9. What is a concordant reading?
10. What is the balanced equation for this reaction?
11. How many NaOH molecules react with one oxalic acid molecule?
12. Why do we repeat the titration?
13. How do you calculate average volume?
14. Why is oxalic acid a dibasic acid?
15. What is the unit of molarity?
16. Can any other indicator be used in this titration?
17. What is a burette used for?
18. What is a pipette used for?
19. What is the use of a conical flask in titration?
20. How is the molarity of the acid calculated?

5 MCQs with Answers:

1. Which indicator is used in this titration?
   Ⓐ Methyl orange Ⓑ Phenolphthalein Ⓒ Litmus Ⓓ None
   Answer: Ⓑ Phenolphthalein
2. Color at the endpoint in this experiment is:
   Ⓐ Pink to colorless Ⓑ Colorless to pink Ⓒ Yellow to red Ⓓ Blue to green
   Answer: Ⓑ Colorless to pink
3. Oxalic acid reacts with NaOH in what ratio?
   Ⓐ 1:1 Ⓑ 1:2 Ⓒ 2:1 Ⓓ 2:2
   Answer: Ⓑ 1:2
4. The unit of molarity is:
   Ⓐ mol/kg Ⓑ mol/L Ⓒ g/L Ⓓ g/mol
   Answer: Ⓑ mol/L
5. The chemical formula of oxalic acid is:
   Ⓐ H₂SO₄ Ⓑ CH₃COOH Ⓒ H₂C₂O₄ Ⓓ HNO₃
   Answer: Ⓒ H₂C₂O₄