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WHAT YOU NEED PER GROUP:
1 dinky cup
1 stirrer
1 measuring spoon
WHAT YOU NEED ADDITIONALLY:
3 jars
1 big jug
2 dinky cups
mineral water
3 wide stirrers (extra)
sodium hydroxide - safley stored!
potassium permanganate
1 bag of sugar
1 pair thermal gloves
1 face shield
1 box nitrile gloves
Welcome the children back to class, what did they do last week?
Last week they did a redox reaction between potassium permanganate and citric acid
Today we are going to do another redox reaction with potassium permanganate, but this time with sugar!
Now it is time for the children to make the first solution.
Choose your assistants dearests.
One will give each group 50ml of deionised/mineral water
The other will give out 1 big spoon of sugar to each group.
Remind them of the rim trick to get the exact measurements (supervise this)
Now all the children must be seated far from your demonstraing table or standing against the wall.
Put on your nitrile gloves!
Fill your jar less than half way with mineral water.
Dip a dry stirring stick into your potassium permanganat, you only need a few granuals on the stick.
Shake them into your water, they look spectacular falling in - wow children look!
Now you stir & stir & stir
wow look at the colour changing to purple!
Now add the sodium hydroxide solution to the children's sugar solution. What will happen when we mix this with the pottasium permanganate?
Add the 100ml solution to the jar in three pours - 1, 2, 3!
Watch the colours change and explain the redox reaction!
That is the first stage of the reaction.
In the second stage, the manganate is reduced further and looses some oxygen MnO4 -> MnO2
This leaves us with a yellow/brown solid called manganese dioxide.
This solid is in such small particles that the solution appears red/brown and then yellow.
The longer you leave the solution, the paler it will look. This is because the manganese dioxide particles will settle at the bottle of the jar.
Repeat the reaction again with hot water, again using the children's suagr solution.
You will now have three jars of the solution to compare the colours. One from the beginning of class and one from near the end. The solution made earlier should be paler.
There is then the hot solution which should have reacted (chaqnged colour) much more quickly.
