Today, we shall take a look at the Tests for Oxidising Agents and Reducing Agents using common chemical reagents in our school laboratories.
Before we can continue, is important to first understand what is a Redox Reaction and how to identify one.
You will also need to know the definitions of Oxidising Agents and Reducing Agents.
A reducing agent is a substance that reduces another substance by:
- giving hydrogen to the substance
- removing oxygen from the substance
- giving electrons to the substance
In the process of reducing another substance, the reducing agent itself becomes oxidised.
Common Reducing Agents are:
- Potassium iodide, KI (colourless solution)
- Reactive metals such as Mg, Zn
- Hydrogen gas, H2
- Carbon, C
- Carbon monoxide, CO
- Hydrogen sulfide, H2S
- Sulfur dioxide, SO2
An oxidising agent is a substance that oxidises another substance by
- giving oxygen to the substance
- removing hydrogen from the substance
- receiving electrons to the substance
In the process of oxidising another substance, the oxidising agent itself becomes reduced. I have blogged about these agents before using the analogy of a property and an insurance agents.
Common Oxidising Agents are:
- Acidified potassium manganate (VII), KMnO4 (purple solution)
- Acidified potassium dichromate (VI), K2Cr2O7 (orange solution)
- Halogens e.g. Cl2, Br2
- Concentrated sulfuric acid, H2SO4
- Nitric acid, HNO3
- Oxygen, O2
In the video below, i will share with you on the step-by-step strategy to test for Oxidising and Reducing Agents using common laboratory reagents such as aqueous potassium iodide, KI(aq) and acidified potassium manganate (VII), KMnO4(aq) solutions.
Test for Oxidising Agent:
Use of a Reducing Agent e.g. aqueous potassium iodide, KI(aq)
Observation: Colourless solution turns brown
Chemistry behind it: 2I–(aq) => I2(aq) + 2e–
Test for Reducing Agent:
Use of an Oxidising Agent e.g. acidified potassium manganate (VII)
Observation: Purple solution decolourises
Chemistry behind it: MnO4–(aq) + 8H+(aq) + 5e– => Mn2+(aq) + 4H2O(l)
YouTube Video Tutorial
Let’s take a look at the YouTube Video now….
Length of video: 16.11 minutes
Direct video link: https://youtu.be/1YQsHwUrT2c
I hope you find the content easy for your understanding and if you have any questions, leave me a comment below. Feel free to share this blog post with your friends and learn the key O-Level Pure Chemistry concepts together.
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PS: Under related articles below, there are several blog post discussions and questions related to Redox Reaction concepts. You can also do a keyword search using the search box at the top right hand corner.