Sciencemadness Discussion Board

Howdy!

HomeSkooler - 15-3-2007 at 07:18

Found this forum browsing around and glad I did. My wife and I are homeschooling our 3 kids (6, 2.5, .5).

I drew the short straw for the science, engineering, history, and politics part of the curricula. I intend to start the science piece soon with chemistry and basic mechanics. So far, we've built a little table top trebuchet to demonstrate leverage and gravity.

What are some chemistry experiments where a young kid can learn something, uses house hold items, and has some "gee whiz!" to it? (Vinegar and baking soda are covered).

Thanks, by the way, to all of you for making this resource available.

joeflsts - 15-3-2007 at 08:03

I guess it depends on what you want to do. For example if you want to do demonstrations to ignite interest in chemistry or if you want to do experiements to back up subjects.

If the former then three are losts of resources on the web to help you with picking some attention getting demonstrations. You should also use the search engine on this forum to gather some great data of beginning experiments.

If the latter then you should seriously consider buying a decent chemistry set and using it as a teaching tool.

Joe

HomeSkooler - 15-3-2007 at 08:31

joe...right now it's just about igniting interest. He's too young for any serious learning.

But...if I can ignite his interest by doing something "wow!!" for about 20 minutes twice a month, then when he's ready for serious study at about 8 years old, the enthusiasm will be there.

roamingnome - 15-3-2007 at 08:43

ive held students interest for a good 20 minutes
with red cabbage pH testing....

the color changes with house hold items are good for kids... and adults who like green...

HomeSkooler - 15-3-2007 at 08:45

Oh yeah....cabbage water! Thanks!

joeflsts - 15-3-2007 at 08:52

Quote:
Originally posted by roamingnome
ive held students interest for a good 20 minutes
with red cabbage pH testing....

the color changes with house hold items are good for kids... and adults who like green...


My little boy (6 year old) is fascinated by color changes. Red cabbage was a big hit with him.

Joe

Waffles - 15-3-2007 at 15:05

Put a hardboiled egg in vinegar :D.

Pyrovus - 15-3-2007 at 20:56

Another nice colour change reaction is that between a solution of copper sulphate and table salt. Upon adding the salt the blue solution changes to a very nice green as a result of the formation of the CuCl4(2-) complex. Diluting the solution sufficiently then causes the solution to become blue once more.

Levi - 16-3-2007 at 04:51

I remember when I was young(er) my father took a milk jug and placed it in front of the heater, after it was suitably warmed he capped it and left it outside in the cold. When it had reached ambient temperature he had me retrieve the container from outside; the jug had completely deformed much to my amusement. Without uncapping the deformed jug it was again placed in front of the heater where it expanded to its original form.

Here are some neat experiments that are easy to do:

You might try dropping a slice of potato in water (control group) and then another slice into a solution of 3% hydrogen peroxide to show how it forms oxygen bubbles.

Adding a bit of salt to soda may also provide some entertainment but it will make the soda taste nasty.

Place a lit candle under a glass and observe what happens when it runs out of oxygen.

Make a chute out of a piece of paper and perform the baking soda and vinegar experiment again using a tall glass. After the foaming, tilt the glass and use the paper chute to direct the CO<sub>2</sub> onto a lit candle. The CO<sub>2</sub> is heavier than air and will follow the chute downward to extinguish the candle. Be careful not to pour the foam or liquid when you tilt the glass.

Good decision with the homeschooling, btw. Don't forget to encourage a social life, though--anyone I've talked to who has been home schooled has that same complaint about not being able to make friends as easily. They are, however, generally a hell of a lot smarter than the apes that wandered the halls of my high school.

[Edited on 16-3-2007 by Levi]

Ozone - 16-3-2007 at 05:13

First, let me applaud your effort! These days it seems like math and science are sorely neglected in primary education (nevermind highschool); if I have kids, their education will be supplemented with math and science at home. Following this, here are a few neat OTC experiments that can be done at home (with minimal safety procedures),

As always, an apron or lab coat and safety glasses are a must (and good practice to start early). You just *feel* like a scientist with a labcoat, safety glasses, and a pocket full of pens:D.

1. The pressure of the atmosphere: place a metal can (with a screw top) onto a hotplate with the cap removed. Heat the can. Using a pair of pliers, remove the can from the hotplate and screw on the lid. Let cool. The heating caused the gas inside the can to become less dense. If no air is allowed to enter the can (cap), on cooling the pressure inside is less than atmospheric (760Torr, 1atm, 101E5Pa) and the can will be crushed by the atmosphere (this can be acellerated by cooling the can with water, caution, this can be startling).

2. Iron filings and sulfur. Demonstrate magnetism with the iron filings. Place Fe and S into a *Pyrex* test tube and heat to redness (stinks a bit, do this outside or with good ventilation) for ~10min. Allow the tube to cool slowly. Dig out the fused mass, break it apart to see that the filings and sulfur are no more. Demonstrate the lack of magnetism of the iron sulfide product.

3. Place and iron nail into copper sulfate solution--diplacement occurs plating copper onto the nail.

4. Place copper wire into silver nitrate solution--silver plates out onto the copper in a neat dendritic form. If the wire is coiled, this resembles a tree (works well with 3 to demonstrate periodicity in transition metals).

5. Iron filings, salt and dilute (10-20%) peroxide--acellerated oxidation of Fe to make rust, this gets quite warm, boils, and evolves red/brown colloidal rust. Do this in a glass container you can dispose of (or if you have it, pool acid can remove the stains). This demonstrates REDOX in a very striking way.

6. Place a drop of water on to a piece of wood. PLace on top of this a beaker or or jelly glass. Add to the glass, ammonium nitrate and a small bit of water, stir. The rxn should soon become cold (endothermic) enough to freeze the water drop. The glass can be lifted and the wood block will be frozen to it.

7. Light sticks are always good!

8. Destroy an old solar calculator. Remove the polarized plastic from the display. Use these (crossed) to demonstrate polarization and the wave nature of light.

Oh yes, I don't know how sicentific it is, but Mentos and diet coke can be spectacular;).

Whew, there are many more, I don't know where to stop. Perhaps it would be helpful if you gave us some sort of insight into your pedagogical plan (then we could fill it).

Good luck and,

Cheers,

O3

[Edited on 16-3-2007 by Ozone]

HomeSkooler - 16-3-2007 at 09:48

Ozone and Levi: thanks for the great tips!!

I didn't know solar cells had polarizers over them. Why is this?

Also, where do you get the ammonium nitrate?

I hadn't thought about the C02 and candle idea. That's really great because I've been TELLING him about how oxygen is what supports combustion. This will be a great way to SHOW him.

One that I like that you all didn't mention: transformer run into a tub of tap water, with each lead in it's own "graduated" spaghetti jar showing decomposition of water.

UnintentionalChaos - 16-3-2007 at 12:40

If you read the packages of ice packs, they will usually say if they contain ammonium nitrate. If they don't say anything, I a. run a quick solubility test using alcohol and calcium chloride....saturated solution of the two in alcohol mixed. If I end up with a snowy precipitate (ammonium chloride has low solubility in alcohol) it's ammonium nitrate. I do not believe that urea (the other common ice pack material) would do this. Other than that, their densities, color, smell (or lack of), melting points, solubilities (in water and alcohol), and common form (prills) are all the same. b. assume the worst and look elsewhere. CO2 can be had in demonstrational quantities by adding vinegar to baking soda in a jar with a cap, and running a tube through the lid into the demonstration vessel.

If you lead the hydrogen into a jar of soapy water, the bubbles will burn with a *whump* If the gases mix and you make bubbles, you will shake dust from the walls with even a few.

[Edited on 3-16-07 by UnintentionalChaos]

Ozone - 16-3-2007 at 20:27

Umm, the solar cells themselves do not use polarizers, the screen upon which you see the numbers does! the LCD works by having liquid crystalline (rod-like, self assembling) polymers (which orinet themselves with regard to an electric field) interact with light passed through them *and* the polarizer. If the molecules all line up at 90° to the polarizer, there is no signal.

Following this, if you remove the polarizer from the display (the green or grey plastic) of a calculator, cut it in half, and rotate one half with respect to the other, it will be opaque (black) at 90°.

NH4NO3 is a common fertilizer (it is, as UnintentionalChaos said, also the principal in cold-packs).

Let us know if we can help,

O3

HomeSkooler - 19-3-2007 at 05:19

Hey guys. This weekend we talked about atmospheric composition. I put the candle in a bowl of water and put a jar on top. The candle of course went out and sucked the water in and I explained that point.

Then, to reinforce it, I did the vinegar/baking soda deal then "poured" the CO2 on the candle putting it out. Went great!

I'm pumped to do the silver nitrate/copper thing, and the ammonium nitrate freeze!

HomeSkooler - 19-3-2007 at 05:20

Ozone, NH4NO3 question. Could you derive that by mixing VERY DILUTE ammonia and nitric acid? None of the home depots or lowes carry it. I can get nitric acid at a local jewelry making shop, however.

But only in gallon quantities :o

Levi - 19-3-2007 at 06:28

Quote:
Originally posted by HomeSkooler
Ozone, NH4NO3 question. Could you derive that by mixing VERY DILUTE ammonia and nitric acid? None of the home depots or lowes carry it. I can get nitric acid at a local jewelry making shop, however.

But only in gallon quantities :o


The answer is yes, but NH<sub>4</sub>NO<sub>3</sub> is soluble in water so in order to obtain any solid product you'll need to boil down your solution and if you have any excess ammonia in your mix it will all boil out upon heating. This, while extremely smelly (use excellent ventillation) is much better than having excess acid in your mix. If you can post the concentrations of your materials here one of the friendly forum goers will be able to help you out with the ratios you need. Again, make sure you use slightly more ammonia than is required. An alternate route would be to add alcohol to the mix to decrease the solubility of the ammonium nitrate but you won't get a full yield this way--this should be fine for your purposes. Rubbing alcohol should work; consult one of the more knowledgeable members if you decide to use this method.

Also, we all know chemistry is great here but the majority of people are quite scared of it. That said, ammonium nitrate was the principle ingredient in the Oklahoma City bombing and you can bet the feds are watching it very carefully no matter what country you are in. It is a perfectly safe chemical to use for your purposes but walking into Home Depot and asking if they carry ammonium nitrate hasn't been safe for a decade. I am shocked that you can get nitric acid by the gallon OTC but don't think that it is by any means a harmless chemical. Use both ingredients carefully.

joeflsts - 19-3-2007 at 10:18

Quote:
Originally posted by HomeSkooler
Ozone, NH4NO3 question. Could you derive that by mixing VERY DILUTE ammonia and nitric acid? None of the home depots or lowes carry it. I can get nitric acid at a local jewelry making shop, however.

But only in gallon quantities :o


Sure, NH4OH + HNO3 --> NH4NO3 + H2O

You will want to use an excess of Ammonium Hydroxide and then evaporate the water. The melting point is 170C so evaporating he water shouldn't be too difficult on a radiator or low heat. Levi is correct that it will produce some Ammonia gas so you'll want do this outside.

Be sure to cool your reactants when mixing (ice & salt) and add the two very slowly. This reaction can be performed safely but you should keep in mind that just dumping stuff together can make it react violently.

Drying the Ammonium Nitrate is going to prove to be difficult unless you use an oven. Just be sure not to use a temperature lower than 170C which shouldn't prove too difficult :).

Joe

[Edited on 19-3-2007 by joeflsts]

bereal511 - 19-3-2007 at 15:25

For the question about ammonium nitrate, I'd probably recommend trying to find a supplier to buy it from. It seems a bit more expensive to buy nitric acid for the purposes of making ammonium nitrate. How much does it cost from the jewelry store? And does anyone know if the people selling ammonium nitrate on eBay are legitamite?

Ozone - 20-3-2007 at 12:33

Sorry, But I have been in and out lately (cumes, work, etc.). For the amount of NH4NO3 you will need, how about buying a cold-pack or two?

Cheers,

O3

Magpie - 20-3-2007 at 12:51

Quote:

I am shocked that you can get nitric acid by the gallon OTC but don't think that it is by any means a harmless chemical. Use both ingredients carefully.


I agree, although I would say "shocked and delighted." I can't buy nitric locally. In fact I just finished making 100mL of nitric acid for my reagent shelf by reaction of con sulfuric (Rooto) with NaNO3 (pottery grade). I had less foaming this time than with the KNO3 stump remover I used last time.

And yes, treat HNO3 with a lot of respect, especially when it is hot.

Aurum - 20-3-2007 at 18:12

One of the simplest precipitation reaction to demonstrate is copper sulphate and sodium carbonate. You can heat sodium bicarb to get the carbonate. When the 2 solutions are mixed a light blue precipitate is produced which is copper carbonate. This can be washed and dried to produce a nice powder. This powder can then be mixed with vinegar to produce lots of bubbles and a nice blue copper acetate solution. This solution can then be mixed with sodium carbonate to precipitate copper carbonate ......

This works better with the potassium carbonate available at pottery suppliers.

If you add ammonium nitrate solution to copper sulphate you get calcium sulphate precipitated.

not_important - 20-3-2007 at 18:54

Quote:
Originally posted by Aurum

If you add ammonium nitrate solution to copper sulphate you get calcium sulphate precipitated.


Really? Learn something new every day. But aren't you worried about radiation from the transmutation?

Washing soda is sodium carbonate, read the label as some products are 'improved' or 'enhanced' and have various sorts of trash in them.

Pottery supply places sell soda ash, anhydrous sodium carbonate. I buy the economic 25 kilo bag. Potassium carbonate is also called pearl ash.

Aurum - 21-3-2007 at 04:35

Should, of course, have been Calcium Nitrate.

bereal511 - 21-3-2007 at 14:45

What I really enjoy is the immediate crystallization of supersaturated solutions of sodium acetate (what a tongue twister). When a crystal of sodium acetate is added to the solution, it forms a growing mass of sodium acetate, which looks as though the liquid had turned into a solid.

Dissolve sodium acetate in water until no more sodium acetate will dissolve. Then slowly raise the temperature of the solution while adding sodium acetate, until you've reached boiling point. Continue to carefully add sodium acetate until no more will dissolve, making sure no crystals are left. Allow the solution to cool to room temperature, then when you're ready to perform the demonstration, just add a single crystal of sodium acetate to the solution.

You could probably make the sodium acetate by the basic sodium bicarbonate + vinegar reaction and boil off the water until you have the crystals. I'm not sure how much you'd need to make a sufficient demonstration, but I'd speculate 50 grams of sodium acetate trihydrate for every 5 mL of water.

[Edited on 21-3-2007 by bereal511]

[Edited on 21-3-2007 by bereal511]

Ozone - 21-3-2007 at 16:02

What's really neat is the exothermicity of crystallization of NaOAc! Re-usable hot-packs are actually sold whic are, in essence, saturated NaOAc with a rough metal piece inside. Bend the metal piece to supply points for nucleation and voila--a solid mass of crystals, and a bunch of heat. These are regenerated by heating them to over the saturation temperature.

Or, make stalagmites by pouring supersaturated NaOAc onto a few crystals placed on a surface. They seed and grow into a mass immediately.

Good one, bereal511!

Cheers,

O3

not_important - 21-3-2007 at 21:53

Sodium acetate - a demo pages with a few photos

http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA3/MAIN/ACETATE/P...

and here with a movie - link is near the top of the left hand column
http://chemmovies.unl.edu/Chemistry/DoChem/DoChem058.html

HomeSkooler - 22-3-2007 at 08:44

Cool!

16MillionEyes - 23-3-2007 at 16:26

I'm going to try that, if I can.