Our website won't work without javascript. Please enable it or upgrade your browser.

Module 1: Practical chemistry for exams›PAG 12.3 - Investigating the reaction between potassium manganate(VII) and ethanedioic acid

PAG 12.3 - Investigating the reaction between potassium manganate(VII) and ethanedioic acid

An overview of PAG 12.3 - Investigating the reaction between potassium manganate(VII) and ethanedioic acid

2 min

On this page

In OCR Chemistry Required Practical 12 (PAG 12.3 ), a redox reaction between potassium manganate(VII) and ethanedioate ions is carried out. An investigation into how acidic conditions affects the reaction is completed, the redox equation for this reaction is:

In OCR PAG 12.3: Investigating the reaction between potassium manganate(VII) and ethanedioic acid, there are several important safety requirements to be aware of (beyond normal lab practice such as wearing goggles).

Immediately clean up any spills of acid.

Experimental method for OCR Chemistry Required Practical 12 (PAG 12.3)

The image depicts a step-by-step experimental method titled 'OCR PAG 12.2'. Steps are numbered 1 to 6 with corresponding images and descriptions.

1. Set up three burettes for solutions: 0.02 mol dm⁻³ KMnO₄ (aq), 0.5 mol dm⁻³ H₂C₂O₄ (aq), and 1.0 mol dm⁻³ H₂SO₄ (aq). Rinse and fill each burette.

2. Prepare a results table. A table shows volumes for solutions: KMnO₄ (aq), H₂C₂O₄ (aq), H₂SO₄ (aq) in cm³, and time in seconds (s) for three experiments.

3. Measure solutions for reaction 1. Use burettes to deliver 10 cm³ KMnO₄ into a beaker, and 20 cm³ H₂C₂O₄ with 0 cm³ H₂SO₄ into another beaker.

4. Conduct the reaction. Mix KMnO₄ with H₂C₂O₄, start a stop-clock, and record time for color change to yellow-brown.

5. Repeat experiment 1 to obtain a second time value.

6. Complete experiments 2 and 3 with the same method, using different volumes from the table.

The table at the bottom shows specific volumes for reactions 1, 2, and 3, with columns for T₁, T₂, and mean time (s).

Prevent parallax errors when reading volumes.

An illustration showing a measuring cylinder with a scale marked from 20 to 25 ml. An eye is depicted on the left side, and a green arrow points to the measurement of 22.14 ml.

Do

Read the burette at eye level and record to

A measurement scale showing values from 20 to 25 ml. Two eyes are illustrated, one pointing to 22.26 ml and the other to 22.02 ml, with red arrows indicating the measurements.

Don't

Read from above or below – this leads to incorrect readings due to parallax error.

Calculate for each experiment as a measure of the initial rate.

Compare the values when the concentrations of and are changed to determine the order with respect to each reactant and confirm the rate equation,

Under acidic conditions, investigate how changing and affects the rate.