The Homely Scientist

Gas?  No, not petrol or the like, apple gas.  As fruit ripens it gives off ethylene gas, ethylene gas also helps other fruit ripen too, but how can you harness it?  Simple, a plastic bag.

Okay I bought some green bananas recently (they were on sale).  Way too green to eat, but I also picked up some apples (mmm, apples).  So I put one apple in the plastic bag with the bananas and this morning they are riper (not completely ripe because someone wanted to eat the apple).  It’s really cool.  This whole process can make for a little fun kitchen experiment.  You’ll need three green bananas, two plastic bags, and one apple.

Put one banana on the counter, no bag.  Put another banana in a bag, no apple.  Put the last banana in the last bag, but with the apple.  Ask your kids which banana will ripen first.  Heck they could even record observations every few hours to see what happens (it happens "quickly", but not "quickly" by kid standards).

Good fun and you can eat the results!

Tags: apple gas, ripening bananas

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Science of course.  Now, the fastest way, and absolutely not recommended, is to use a CO2 fire extinguisher and blast the can of pop.  That will chill it like nobodies business, but … let’s skip that one and try something a) safer and b) easier.  It’s as easy as ice, water and the magic ingredient … salt.

I saw this on a Mythbusters episode but LifeHacker just posted about it recently.  Truth be told, the Mythbusters episode chilled beer, not pop.  Regardless the principle here is the same.  Okay water will chill things, water is an awesome conductor of heat.  Okay add ice and it gets colder.  In fact ice water is colder than just plain ice (yep, it’s true).  The thing is speed, so how can you make ice water even colder … you need to lower the freezing point of water below 0C/32F.  Huh?  How?  Salt.  Notice how the ocean doesn’t freeze often, even in northern climate (Poles excluded)?  Ever wonder why you put salt on icy sidewalks to melt the snow?  Why you add salt to the ice when making ice cream?  All the same reason, salt lowers the freezing point of water several degrees.

So adding salt to the ice water makes it even colder that the freezing point of water and swirling the beverage of choice around lets the water take the heat out of the drink faster as well.

Now you’re ready for your next holiday party when you forgot to chill the bevvies.

Tags: chill drinks fast

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I got a fun link from my good friend Laura over at CFS Stories, throwing hot dogs to calculate Pie.  No, really I’m serious.  I read through the article and it all makes sense.  Now, I’m not too crazy about throwing good food on the floor, so I think using something like a piece of PVC pipe or wooden dowel might be better.

Have I tried this yet?  Are you kidding?  We’re still having the occasional power issues and the water system is still coming online.  Maybe another snowy day.

Tags: Pi, calculating Pi

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Hsien-Hsien sent this YouTube video my way last week.  Okay the cuteness factor can be a little much, but the experiment is very cool and shows one of the weird science things that is also fun for kids: corn starch and water.  Here’s the video:

Okay corn starch is just some wild stuff.  In solution is has the property of when hit hard it acts like a solid, when pushed gently a liquid.  You can add more water and make slime (little food colouring makes it even more fun) … I hear a little liquid soap in the mix makes for slimier slime.

Related to this are some unstable clays.  These are awesome.  I think those deserve another post on their own, but here’s the gist.  There are clays (especially in San Francisco) where the clay crystals are arranged in a way to support stuff on top of them (e.g. buildings, bridges), but when jostled (e.g. earthquakes) the crystals re-arrange and lay flat and this also allows water trapped in the mixture to get out … making … mud!  And also the buildings, etc collapse because there isn’t anything to really hold them up.

Truly amazing.  Dr. Bob talked about an uber-messy demonstration of this he used to do, but I never got to see it.  Oh well.

Tags: solutions, corn starch, quick clays, liquifaction

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I was up late watching TV and I saw an episode of Mythbusters that I hadn’t seen before.  It was done over the summer and it featured, yes you guessed it Diet Coke and Mentos.  They answered a lot of the questions surrounding this fun little experiment and clarified for my why the B-day part coke geyser, didn’t geyser.

Okay first thing, it has to be Diet Coke and mint Mentos.  I’ll get to the reasons in a second.  I did use mint Mentos, but cheepo regular cola for the geyser and that’s why my geyser was a tad whimpy.

The question for the Mythbusters wasn’t if it worked, but how it worked.  Clearly it had something to do with CO2 and the candy.  So Adam and Jamie compared DC (Diet Coke) and soda water.  The DC had a much bigger reaction to a single Mento than soda water, so it must be something other than just candy and CO2.

Adam gathered some of the component parts of DC, Aspartame, caffeine, potassium benzoate, citric acid, and phosphoric acid and tested each one in soda water.  Turns out that Aspartame, caffeine, and potassium benzoate all react strongly with Mentos.  Ah hah!

So what’s happening to get a ten foot geyser is a cascading reaction with the three components and the Mentos to release a lot of CO2 all at once.  Great, but why.  Nucleation.  Nucleation is, like I’ve talked about before, the reaction between the surface of the object and the liquid to encourage the CO2 out.  The rough surface of the candies gives the CO2 something to cling to and then release.  Because the candies are heavy they sink to the bottom where they force the reaction in the greatest volume of liquid and giving the CO2 lots of space to push out … and hence the geyser!

So there it is.  I need to use Diet Coke so I get the aspertame boost.  I need to use mint Mentos for the maximum nucleation sites.  I see another geyser in the future …

Oh the picture?  That’s Keri Byron who did a spread for FHM on Mythbusters.  Yep I think she’s a hottie.

Tags: Diet Coke Mentos, coke geysers, mentos coke, Keri Byron, Mythbusters

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Remember my homemade barometer?  Come on I just wrote about it on Monday ;-)!  Seriously here’s a little update for you.  First, as you can see, I’ve coloured the water to make it easier to see.  The water level in the tube isn’t accurate.  I quickly opened and closed the top to fill the tube a bit for the picture.

Next … I’ve made two more!  These two are for my daughter’s Grade 4 class (studying meteorology remember) and my son’s daycare.  I have enough tube and bottles to make another one or two if need me (I think Lorraine’s niece might like one for her class … I’m going for the wacky uncle who is always doing strange experiments thing).

Now why am did I make one for my daughter’s class (besides that I’m a geek and I just love this stuff)?  Because one of her teachers mentioned that she was going to make a balloon barometer.  Which will also work.  The air expanding and contracting in relation to atmospheric pressure would make the balloon get bigger and smaller and this could be measured.  But … as we all know balloons lose air over time.  So at some point the device will lose effectiveness because there isn’t enough air to left to make it work.  These, however, will keep working as long as there is water in them.  No, I’m not bragging, it’s just one of those science things.  The balloon will be great for a while, but won’t last more than a week I’d think.  These can be there for the whole year and beyond!

Tags: homemade barometer, experiments at home, waeather fun, weather instruments

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I love the weather.  I’ve already talked about my favourite weather signs, now what about something a tad more scientific.  How about a barometer?  Making one is really, really easy and I’m going to show your how.  The kind I’m going to show you is called a weather glass.  You can find them in home and garden catalogs, but come on, let’s just make one instead!

Before I get into the make, let’s talk about what barometers do.  Barometer’s measure the minute changes in atmospheric pressure that indicate changes in weather.  Minute?  Yeah, really, really small.  Okay low pressure (usually associated with rain) is about 29 milibars, high pressure (nice weather) is about 30.  One freakin’ millibar that’s it!  Barometers used to be all done with liquids, because they are prevalent and easy to deal with.  How?  Simple, it’s all PV=nRT.  Universal gas law.  With temperature relatively constant, changes in pressure will change the volume.  Uh huh.  Okay, here’s what’s going on.

The bottle is filled with water almost to the top and closed.  At the bottom I’ve cut a small hole and used silicone caulk to seal a narrow plastic tube in.  I used a little more caulk to stick the tube to the bottle.  Okay, note in the picture that the opening of the tube is well below the top of the water.  This is really important.  So as the pressure from the air pushes down on the narrow opening it changes the water level.  Higher pressure, lower level in the tube, lower pressure, higher in the tube.  As you can see the water is at the top of the tube and when I took the picture … it was raining.  In fact, the tube is nearly overflowing right now.  As the storm clear, high pressure will take over and push the water back down.

Now, as low pressure heralds a coming storm, you watch your weather glass for when it rises more than when it falls.  You want to know when it’s going to rain, you can tell when it’s clearing up.

So making it … I described it above, it’s really that simple.

Here’s exactly what I used.  Some things I figured out.  The bottle needs to be almost full so that the tube will be the sensitive part, not the air above the water.  Too much air and the tube level will not change.  Also keep the bottle out of the sun.  Why?  Temperature.  If the bottle warms and cools it will be temperature not pressure making the water level rise (the increased temp will increase the volume of the water making it go up).

It will take about 5 mins to make this, about 30 mins to dry enough to fill, and a day to get things acclimated to be able to predict the weather.  Except for the cutting the hole part, very kid friendly project.  Yes, I would also put food colouring in the water to make it easier to see.

This first one was the prototype.  The next one I’m going to make will be for my daughter’s class.  They’re studying weather, don’t ya know.

Tags: barometers, homemade barometer, predicting weather

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Yep I finally did it.  My daughter had been begging me to do one.  She’s seen the pictures, the movies, all of it.  So for her b-day party at my place …

Her very own Mentos-coke geyser.  Yeah it didn’t go as high as I had hoped (I didn’t get all the Mentos in at once), but I did it and I’m sure I’ll be doing it again.  Lorraine took the pics using the rapid-fire setting on my camera so you can see the whole set here on Flickr.

Tags: mentos coke geyser

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Ever wonder what to do with a foam take-out container?  I think I have the answer, via LifeHacker.  On team droid there are some pretty easy plans for taking a foam container and turning it into a nice glider.  Sure paper airplanes are fun, but think about the fun after a lunch with the kids and then making some cool gliders?  Yes, you need to wash them first.  Supplies?  Well if you have a marker and a pocket knife you should be good to go.

Hmm … I’m thinking McD’s hotcakes are in my future.

Tags: foam gliders

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Okay you parents can do them too.  Fellow b5-er Jason had this post on science experiments to try (thanks Cory!).  From the Independent had a great list of experiments, but now they are behind the walled garden.  Sigh.  Well looks like I’m going to be on the hunt for these.

• Salt and marble mystery
• Soda fountain
• The ‘egg in the bottle’ trick
• Floating fizzy drinks
• Clouds in a bottle
• Gravity in action
• Make your own lava lamp
• Orange life jackets
• Invisible ink
• Quicksand science

Okay … some of these I know and will write up (invisible ink … lemon juice works great).  Hi ho, hi ho, it’s off to Google I go …

Tags: science for kids, science experiments, kids, science

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