Australia's Science Forum

Hi Everyone
Does anyone out there know a good experiment for turning cobalt chloride from red to blue.
Thanks Krysia

it is blue when it is dry, so I don't know of an experiment to do this... I use a hair drier to dry out the paper strips and dissicator beads when they are pink.

One of our teachers used this the other day - to show transpiration in leaves. Soak filter paper in cobalt chloride solution and dry in air oven . Put in a plastic bag and seal around leaves of plant. Paper turns from pink to blue. TADA!!!

Did I get it wrong? it is pink when dry? Oh well, then in that case anything that makes it absorb moisture from the surrounding environment will make it blue

cobalt equilibria-year 12 chemistry
cobalt solution - 1g of CoCl2.6h2O in 10 mL of 2 - propanol. Then add water dropwise until the deep blue solution just turns pink
1 ice bath
1 water bath at 100 degrees C
http://www.youtube.com/watch?v=BGfYf8OQzuk

Yes, we use cobalt chloride to test for water. In reaction to produce H2, we test by a "pop" test and then place a piece of CoCL2 paper in the mouth of t/tube to show a reaction of H2 with O2(from air) to produce water.
Chemistry teacher does equilibrium reaction with CoCL2 solution. I can look it up, if you want.
Lada

Cobalt chloride paper is blue when dry and pink when moist. I keep my strips of paper blue by putting them in an airtight(?) jar with a layer of blue silica gel beads on the bottom to absorb any moisture. I replace the silica gel when the beads become pink.
Lyn.

Using dry blue cobalt chloride paper
just touch it with sweaty fingers, put it on forehead especially after exercise.
"what's in a breath?" Breath on it!
"What happens when fuels burn?" Hold a clean test tube containing cold water just above the top of the flame (bunsen or other different fuels for comparison)) . If you see any "misting up" or droplets of clear liquid touch it with the bllue paper as a test for water. Soot (carbon) may be deposited too.
Rosalie (another one)

Hi All,

Cobalt Chloride soaked filter paper is a better option as this will allow you to use it in a range of applications.

Cheers,

Robb.....

Hi thanks for all the answers.
Jazz thats exactly what I was after its for a year 12 equilbrium prac. I got it to work using concentraed (10M) HCl but am reluctant to let the girls use that. Teacher said she'll dem it but I'll give your suggestion ago. Its sounds great.
Thanks again.
THE WEEKEND IS GETTING CLOSERRRRRRRRRRRRRR. Hang it there everyone.
krysia

sorry from blue to pink - blame alziemers...

That Al Zeimers has got a lot to answer for. He's starting to hang around far too often lately.

Jazz
everyone here has now done your cobalt equilbria prac and its an absolute winner. Such pretty colours too. Thanks alot for your help.
Krysia