Tuesday, 24 November 2009

So Sweet !

I do enjoy teaching Year 7. They are still at the stage where they can be awed by simple science. Today I had fun with two small experiments.

In the first, marble chips reacted vigorously with acid, giving off carbon dioxide which could be collected in a little pipette and bubbled through limewater, turning it cloudy: the whispy patterns made in the limewater drew appreciative "ooohs" and "aahhhs".

The second experiment was even more fun: magnesium added to acid, giving off hydrogen gas... which made a satisfyingly squeaky bang when tested with a lit splint!

8 comments:

Zephyrinus said...

Does the Hobbit know you're doing these things ?????

George said...

Magnesium and acid - pah!!!! A pop and a poof followed by a whisp of smoke and it's gone - whaaaaa... that's for babies!

Now if you want to see what hydrogen can really do...... Give the kids some real science - Mac follow these instructions:

Ingredients - large plastic tub, cold water, personal protective equipment, 1Kg Sodium metal in paraffin oil (if no sodium then potassium will do - it's more reactive and hence more fun!)

1 - Fill large tub with cold water and stand in playground
2 - Create a barrier at least 20 paces from said tub and stand class of budding scientists behind under strict orders not to move
3 - With the aid of steel tongs, wearing leather gauntlets and eye protectors carefully remove a 'goodly lump' of sodium metal from the safety container and proceed to drop into the tub of water
4 - Run for cover behind the line of kids and watch the firework display! Now this reaction gives off loads of hydrogen which ignites spectacularly as the sodium reaction with water releases much heat.
5 - I'm reliably told that Caesium is even more fun as it is even more reactive than Potassium!

Watch here:

http://www.youtube.com/watch?v=fLJ4FH7q0EQ&feature=related

and here:

http://www.youtube.com/watch?v=vJslbQiYrYY&feature=related

for Caesium see here:

http://www.youtube.com/watch?v=vJslbQiYrYY&feature=related

and Francium is even more reactive but also Radioactive see here:

http://www.youtube.com/watch?v=CxOxebbYgLk&feature=related

End of chemistry lesson on the alkali metals. Science IS fun!

The Cellarer said...

Up here at least, my favourite at school (80's), is now banned. It was having a large container of water, with a screen in front, to which the teacher added, I think Sodium, which danced around the surface.

Some teachers could be goaded into using a more reactive element, I think it was Lithium, which had a habit of jumping the screen...

Mac McLernon said...

George - nice idea... except that

(1) caesium and francium, being radioactive as well as very reactive, aren't generally allowed in schools (I know, I know... I'm such a killjoy!),

(2)technicians, being more fiscally parsimonious with faculty funding, don't dish out "goodly lumps" of anything as expensive as sodium and potassium, and

(3) you may not find magnesium and hydrogen very impressive, but Year 7s still do, which is why they are such fun to teach... and the important thing is that, with magnesium and acid, THEY get to DO the experiment rather than just watching me.

Cellarer - it's lithium which only dances on the surface... sodium can jump the screen, unless you are a canny Science teacher and you stick a piece of filter paper under it first, in which case the hydrogen bursts into flame... potassium bursts into flame (a nice lilac one) without the filter paper...

Mac McLernon said...

Oh, and we're still allowed to do it... albeit only as a demo.

gemoftheocean said...

Mac, I would have LOVED you for a science teacher. I probably wouldn't have gotten such relatively crummy grades in Chemistry. We just learned how to balance "Moles" [borrrrring!]

With you I would have learned what I thought I was signing up for: i.e. "how to blow up stuff."

[George, you're scaring the crap out of me!!!]

You probably would have hated me as a science student though. Scored really well in topics I was personally interested in -- couldn't give a flip about topics I wasn't, so in consequence was bone idle lazy. I'd have made you bald! ["Karen, why can you manage to label every bone in the body, but not remember what acids there are in the stomach? You're going to drive me insane!"

In bio, My lab partner and I never did manage to get our fruit flies to reproduce. We kept putting two males or two females together. DUH. At least we succeeded in keeping our gold fish alive when we studied blood flow in the critters. Our bio teacher had enough sense NOT to say anything when he was standing behind [oblivous!] us, when my lab partner muttered "***damn you, STOP flipping around!!!" We suddenly sense his presence, he walked away laughing to himself.

Delia said...

The lime cycle is also quite fun - slaking lime can be really dramatic – and it's also practical: how to make lovely lime plaster!

I was talking to a friend of my goddaughter last night who is trying to set up a new charity called 'Equipped' (I think), which would aim to collect redundant scientific equipment from schools to send to classrooms in the developing world, and also try to put the classes in contact. She (Lucy) is setting up a website and is applying for charitable status. Sounds a good idea, I think; can let you have more details when I have them if you're interested.

Ches said...

Er, I'm still at the stage when I can be awed by simple science ...!

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