Are Rabbits clever?

One day a fox bumps into a rabbit and says " Hello little rabbit, what are you up to?"
" I'm studying about how rabbits eat foxes"
" Come on, you know that is impossible"
" Well, follow me and I'll show you" said the rabbit.
They both go into the rabbits dwelling and after a while the rabbit comes out with a satisfied smile.
Along comes a wolf. " Hello little rabbit, what are you up to?"
" I'm studying how rabbits eat wolves"
" Are you crazy?"
" Come with me and I'll show you."
As before , the rabbit comes out with a satisfied grin.

I'm sure you've guessed- inside the rabbit's dwelling, there is a huge big lion with the carcass of a wolf and a fox beside it.

The moral of this story is- its not the quality of what you learn, its the teacher that counts!!

Golden Rain

I guess most chemists know that the lead halides are sparingly soluble salts which are reasonably soluble in hot water. Lead iodide is a startlingly yellow precipitate when lead nitrate is mixed with potassium iodide. Usually I give the students ( 13 y.o. level) sample bottles of 0.1 mol/L of the two salts, a 10mL and a 100mL measuring cylinder, two beakers, one with distilled water and the other with ordinary tap water and a 250 mL conical flask.
I then tell them the instructions will be delivered verbally, so they must listen carefully
" Look at me when I'm talking to you".
Then - " put 5 mL lead nitrate into the 10 mL measuring cylinder and transfer to the conical flask- wash out the 10 mL measuring cylinder first with tap water (fill 3 times and empty) then with the distilled water( fill 4 times and empty) - then add 40 mL of distilled water to the conical flask- then put 5mL of the potassium iodide into the 10 mL measuring cylinder and carefully add to the conical flask".
By now the kids imagine this complicated set of steps is the only way to achieve the bright yellow colour, so they are proud of their achievement.
-then I get them to heat the contents of the flask until it just reaches boiling point- the yellow ppt. will now have disappeared. I let them allow the contents to cool while they write up what they did. Soon the oohs and aahs are heard around the room as the Lead iodide reappears as sparkly little crystals - with the blinds down and the side lights on the contents glitter like golden rain.
They love it

Shake the bottle and make it blue

Here is a quick little mix of chemicals to put in a bottle so that when you shake it , it will go blue. Put 5 g. glucose + 5 g. NaOH into 1/2 litre of tap water and add 1 mL of methylene blue. The solution should be colourless, but when you shake it, dissolved oxygen converts the hexose to glucuronic acid ( glucuronate in the basic solution, which gives a blue colour with the methylene blue- this will fade in time to just a thin blue layer on the surface that is in contact with the air.

The Old Nassau

The old Nassau experiment involves making MercuryII iodide which will precipitate as bright yellow/orange and then xs iodide will be converted to iodine by iodate and in the presence of starch give a blue/black colour. If you control the quantities carefully, you can carry a magic wand and shout " yazzooo" just as it goes yellow and then a few seconds later shout " blogwortz" just as it goes blue

The recipe:- Solution A - 4g starch in a little H2O to make a paste, + 500 mL boiling H2O + 13.7 g of sodium metabisulfite to 1 litre H2O

Solution B - 3g of mercury chloride to 1L H2O

Solution C - 15 g KIO3 to 1 L H2O

Mix 1:1 A & B then Add to 1 part C
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Kiwiman

Author:Kiwiman
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