copper into silver and gold

[rell]

Hi everyone, i have a teacher who has seen, what he calls " a great prac" on Youtube.
It uses copper coins, Zinc powder and 3M Sodium Hydroxide.
Im not comfortable with this. Has anyone done this prac and could advise me if i should let him do it.
Thanks
Rell

[Jazz]

this is alloy experiment
teachers demo in fume hood
SAFETY: Do NOT dry the pennies with paper towels. Small pieces of zinc on a paper towel can ignite and cause a fire in the lab.
Zinc powder can spontaneously combust as it dries. Make sure you leave no clumps of zinc on paper towels, and place all excess zinc in the waste beaker provided by your teacher
I sugest using zinc granules instead of zinc powder

[rell]

Thanks Jazz

[smiley]

Hey we do it every year - but only with Seniors.

Tips: Overheating USA pennies will cause them to melt, because an American 1c piece is actually a copper sandwich, with a lead centre. Foreign Asian coins, or PNG 1 toea pieces work well.

Make sure you check the tongs, and remove any that work like Woolworths bread tongs (i.e. not meeting in the middle )

I usually put the strong NaOH into a small evaporating basin, not a beaker - seems to be safer.

Big emphasis is placed on safety and correct procedure, but it does have a fairly cool "wow" factor.

[linotas]

Yes, our seniors do this prac as well. In the past the teacher has had a stash of old 1c coins, but this year we used various foreign coins from my vast coin stash. Just be careful with waste. This year we had a nice little waste paper bin fire

[mtg]

What's the prac? I want to do it now, it sounds like fun.