Manganese dioxide and hydrogen peroxide prac

[Rita]

Hi All
Has anyone done this prac with year 9?
Teacher wants dropper bottles of hydrogen peroxide and lots of manganese dioxide powder along with test tubes, splints and matches.

What strength peroxide do I prepare?
Please help!

Rita

[Tina]

Hi Rita
I think from memory we use 6% hydrogen peroxide. Either that or 3%. I only ever stock these two strengths. The 3% one you can buy from the chemist. You wouldn't need stronger than 6% I dont' think but I can't find my records on it. Someone else may prove me wrong.

We tend to do that exp. for yr 11 chem (catalysts). What context are you using it in for year 9?

[dolphinscales]

the 3% will do it

[Lis]

Hi Rita
we did this prac last week, and used 3% hydrogen peroxide, didnt get any complaints.
Lisa

[Mother]

Hello Rita
I,like the other chemtalkers say that 3% is the way to go.However when you mix hydrogen peroxide with manganese dioxide the reaction does create a lot of heat, it can get very hot!!! and bubbles up.
The manganese powder is a very fine,light powder so needs to be handled carefully.
Cheers
Mother

[Lyn]

We did this a few weeks ago. Side arm test tubes with rubber bungs and clear plastic tubing attached to sidearms. I prepared the test tubes by adding a spatula of manganese dioxide to each tube which means that the kids don't have to mess around adding the powder themselves. I gave the teacher 10 x 50ml beakers with about 10-15ml of 3% hydrogen peroxide in each beaker. I demonstrated to the class the method of catching the oxygen by placing the tubing so as to catch the oxygen in an upturned test tube full of water. The kids could see the displacement of the water as the oxygen bubbles filled the test tube. Most of the students were able to get their glowing splint (satay stick) to burst into flame when it was placed in the test tube of collected oxygen.
Lyn.

[franco]

I make a manganese dioxide/plaster of paris slurry and when set, break into small chunks to fit the test tubes. These can be recycled more easily than the powder and there is much less mess to clean up.
Cheers,
Fran

[Jen1]

yes I mix it with plaster of paris and break into chunks too. Easier to clean up and easier for the kids to see that it is a catalyst as the chunk stays the same.

[lada]

This is a very good idea. What proportion of manganese to plaster of paris? i am going to do it as well. The powder is very messy.
Thanks
Lada

[Labbie]

Yes this sound just perfect. Its a great idea.

[Ocean Breeze]

I use 6%. That way I can less of it.and much less of the Mg O2 so it wont spill over

Store the bottles in a fridge or a cool place. Start with the H2 O2 COLD
decant the droppers back into a larger, capped cbottle when the prac's over .
Dont let it get on skin

[Jen1]

Sorry, it was so long ago that I made it (plaster of paris with manganese dioxide) but from memory it was make up a slurry of plaster of paris and add enough powder to give it a nice black colour. Sorry I cant be more precise than that but it doesnt have to be an exact amount.
Then pour it out to dry and make sure it isnt too thick (5mm should do) and then it is easy to cut up into pieces.

[franco]

I agree with Jen, enough MnO2 to give a really dark colour. One year I used old plaster of paris and even though it set, it must have absorbed moisture from the air so the first time it was used it disintegrated. It still worked ok, just couldn't be recycled.
Cheers,
Fran

[Rita]

Thank you all very much. 3% we'll try first.
Another teacher may use the plaster of paris method though.

Once again thank you
Rita

[smiley]

I do the plaster mix thing too, but I drip little blips of it onto gladwrap, about the size of choc chip bits, and let them dry that way. Then just peel them off the plastic and store them in a jar.