kitchen experiments

nitroboy

does anyone know any good science experiments that can be done easily in the home like blowing up balloons with baking soda and water.

obviously ive far too much time on my hands, watched too much telly and have no money to go out and enjoy myself,

PrecariousNuts

Theres an easy way to measure the speed of light at home. Put a strip of cheese or something into the microwave and get rid of the rotating table, turn it on for a few seconds or so to melt it a bit. Take it out and the distance between two melted or two non melted sections is wavelength/2 or the distance between a melted and non melted bit is wavelength/4. Get the frequency of the microwave from the manual or something and then the velocity = frequency*wavelength.

boy1er1990

yeah i tried a good one!


Fill a can up witha small bit of water!! just so it fills the bottom
a coke can would be good! heat it up on the stove until it bubbles


Be Careful

Use tongs to Quickly put it upside down in a bowl full of cold water

THE CAN WILL CRUSH UP !!!

its cool!

ecksor

Nice example but just to mention a couple of things,

First of all, what is the experiment supposed to demonstrate? (in this case I suppose we want to show what happens when the pressure outside the can is greater than the pressure inside the can due to the vapour condensing and the air contracting?).

Secondly, and more importantly, as you say "Be Careful", but I'd like to remind people to please check the charter for what it says about advising dangerous procedures on the science forums. I don't think yours qualifies but it reminded me to mention it!

aj3001

nitroboy wrote:

does anyone know any good science experiments that can be done easily in the home like blowing up balloons with baking soda and water.

obviously ive far too much time on my hands, watched too much telly and have no money to go out and enjoy myself,

Right, I dont know a huge amount except explosives, try searching on google (I am too busy to do it myself for the moment) for: Nitrogen Triiodide, chemical forumla NI3, has been used for years as a joke, very easy to make, stable when wet but takes 1-2 hours to dry, once dry the slightest movment will set it off, if you only use small amounts its perfectly safe, maybe afew purple iodine stains if anything.

Obviously you can perform electrolosis on water and collect Hydrogen and then fill a balloon with it and set light to it (from afar).

Errm, I am trying to think of safe stuff for you to do but I cant think of much else, oh yeah a water bottle rocket is fun, but I am not entirley sure about the construction of one though so that you will have to search on google as well.

Capt'n Midnight

kitchen scales + oven , means you can do dry weights.

or if you get a lot of golden syrup and warm it up in a tray and look at with polarised filter you should see hexagonal convection cells like those on the surface of the sun or molten basalt that formed the Giant's causeway

Microwave ovens run at about 2.45 GHz for the speed experiments , and don't forget the glass of water to adsorbe reflected microwaves, marshmallows can also be used

Jane Doe

There's a custard powder bomb experiment we did in chemistry but it didn't work so we put explosives in instead. We did it for the open night and fooled all the kids. Ha ha... Bet they're at home trying it out now!

breadmonkey

PrecariousNuts wrote:

Theres an easy way to measure the speed of light at home. Put a strip of cheese or something into the microwave and get rid of the rotating table, turn it on for a few seconds or so to melt it a bit. Take it out and the distance between two melted or two non melted sections is wavelength/2 or the distance between a melted and non melted bit is wavelength/4. Get the frequency of the microwave from the manual or something and then the velocity = frequency*wavelength.

I'm a little confused by this, could you explain it a bit please? Thanks

PrecariousNuts

Sure, a microwave sets up a standing wave inside the chamber with a node (point of no displacement) at either end (you can think of it as a closed pipe really) and the antinodes (point of maximum displacement) and rest of the nodes in the middle. At an antinode the food is cooked and it's not cooked at the nodes. Thats why there is a rotating table so that your food won't be raw in some sections and cooked in others, by continuously moving the food through nodes and antinodes.

If you think of a wavelength starting at a node then it goes it to an antinode back to a node then to an antinode and finally back to a node (Hard to explain without a diagram). So the distance between the two nodes is half the wavelength and then half this distance is the distance between a node and antinode. As I said earlier at an antinode the food is cooked the most and at a node it's cooked the least. So measuring the distance between a node and antinode gives you the wavelength/4. The rest is trivial.

breadmonkey

I understand the node and antinode stuff because I've done some physics. But, are you saying that the microwave sets up just one standing wave in the chamber? I would have thought there'd be thousands (?) I mean, if there was just one, wouldn't the food get cooked at just one tiny point?! And if there are many, wouldn't the whle piece of cheese be melted and you wouldn't have anything to measure?

PrecariousNuts

Well contradictory to it's name the wavelength of the waves in a microwave are in the centimetre range (the why those holes on the front look so big). So the anti/nodes are spaced far enough apart to be measurable. I'm going to guess that there might be 15-30 harmonics in there?

Capt'n Midnight

PrecariousNuts wrote:

Well contradictory to it's name the wavelength of the waves in a microwave are in the centimetre range (the why those holes on the front look so big). So the anti/nodes are spaced far enough apart to be measurable. I'm going to guess that there might be 15-30 harmonics in there?

Not too many harmonics due to the way the microwaves are generated. Full wavelength is between 5 and 25 cm ( not to spoil the fun ) so easily enough to manage.

You could also use a microwave to see what substances heat up and which don't NB. don't forget the mug of water to stop the microwaves "building up" and do under low power for a short time only and do remember to let it stand for a while after in case of superboiling
eg: Oil / paper / wood / granite - you could also measure the temperatures of water, ice, salty water, and the difference between meat and exposed bones - is the meat hotest near the bone - is this because of the bone ?
How about an ice cube in oil ?

Delphi91

ecksor wrote:

Nice example but just to mention a couple of things....Secondly, and more importantly, as you say "Be Careful", but I'd like to remind people to please check the charter for what it says about advising dangerous procedures on the science forums. I don't think yours qualifies but it reminded me to mention it!

Its actually a demonstration experiment used in Junior Cert science to demonstrate air pressure. In the book that I teach from, they use an old 5 litre (?) oil can, the kind that was rectangular and had a handle on top. After letting the water boil for 5-10 minutes, you turned off the heat and after a few seconds (to allow the expanding gas to escape), you put the cap back on and left the can alone. It starts to crush under the atmospheric pressure due to the partial vacuum caused by the cooling air inside. Its quite dramatic.

You can do the same with a 2 litre plastic bottle if you pour some boiling water into it and leave it for a few minutes, then re-cap it.

Mike