Mixing liquids that add up to less than the sum of the two.
Discussion
Question for the science minded PHers here:
I recall a demonstration where 100ml of one liquid (water perhaps) and 100ml of another (alcohol of some sort) are mixed and the resulting cocktail is less than 200ml in volume. It's meant to demonstrate that the molecules of one liquid will fit between those of another.
Mrs Eleven (a supply school teacher) needs to do some fun experiments with her class next week and I suggested this one. However can anyone remind me what liquids are best to bring about the most dramatic effect please? They need to be easily obtainable obviously.
Any other fun experiments related to "dissolving" (easily performed) also appreciated!
Many thanks.
I recall a demonstration where 100ml of one liquid (water perhaps) and 100ml of another (alcohol of some sort) are mixed and the resulting cocktail is less than 200ml in volume. It's meant to demonstrate that the molecules of one liquid will fit between those of another.
Mrs Eleven (a supply school teacher) needs to do some fun experiments with her class next week and I suggested this one. However can anyone remind me what liquids are best to bring about the most dramatic effect please? They need to be easily obtainable obviously.
Any other fun experiments related to "dissolving" (easily performed) also appreciated!
Many thanks.
Water and methanol (methyl alcohol), if I recall correctly.
Might be with trying with methylated spirit (10% methanol, 90% ethanol) as it is the sort of thing somebody might have lying around (and they probably don't like methanol in schools these days).
(Mixing corn flower with water is much more fun for children, by the way. Plenty of stuff on Youtube)
Mike...
Might be with trying with methylated spirit (10% methanol, 90% ethanol) as it is the sort of thing somebody might have lying around (and they probably don't like methanol in schools these days).
(Mixing corn flower with water is much more fun for children, by the way. Plenty of stuff on Youtube)
Mike...
Here you go, this is the experiment you were looking for:
http://chemistry.about.com/od/lecturenotesl3/a/mis...
http://chemistry.about.com/od/lecturenotesl3/a/mis...
otolith said:
Here you go, this is the experiment you were looking for:
http://chemistry.about.com/od/lecturenotesl3/a/mis...
That's the boy. Though, as far as my enfeebled brain recalls our science teacher at school managed more than 4% "loss".http://chemistry.about.com/od/lecturenotesl3/a/mis...
When this was taught to me (sometime in the mid 80s!!) our teacher did not use liquids at all, but as I remember it was something like dried chickpeas or normal peas, with a much smaller grain like rice.
He showed the volume of rice and chickpeas separately, then mixed them and shook the jar and demonstrated that they settled together in to a lower volume than the sum.
It was a lovely simple demonstration of the principle.
He showed the volume of rice and chickpeas separately, then mixed them and shook the jar and demonstrated that they settled together in to a lower volume than the sum.
It was a lovely simple demonstration of the principle.
Brilad said:
When this was taught to me (sometime in the mid 80s!!) our teacher did not use liquids at all, but as I remember it was something like dried chickpeas or normal peas, with a much smaller grain like rice.
He showed the volume of rice and chickpeas separately, then mixed them and shook the jar and demonstrated that they settled together in to a lower volume than the sum.
It was a lovely simple demonstration of the principle.
Apologies for the cut and paste, but reminded me of this:He showed the volume of rice and chickpeas separately, then mixed them and shook the jar and demonstrated that they settled together in to a lower volume than the sum.
It was a lovely simple demonstration of the principle.
beer philosophy said:
A meteorology professor stood before his Meteorology 101 class and had some items in front of him. When the class began, wordlessly he picked up a very large and empty glass mayonnaise jar and proceeded to fill it with golf balls. He then asked the students if the jar was full. They agreed that it was.
The professor then picked up a jar of pebbles and poured them into the jar. He shook the jar lightly. The pebbles, of course, rolled into the open spaces between the golf balls. He then asked the students again if the jar was full. They agreed it was.
The professor picked up a box of sand and poured it into the jar and of course the sand filled up everything else. He asked once more if the jar was full. The students responded with an unanimous yes.
The professor then produced two cans of beer from under the table and then proceeded to pour the entire contents into the jar, effectively filling the empty space between the grains of sand. The students laughed.
"Now," said the professor, as the laughter subsided, "I want you to recognize that this jar represents your life. The golf balls are the important things -- your family, your partner, your health, your children, your friends, your favorite passions -- things that if everything else was lost and only they remained, your life would still be full.
"The pebbles are the other things that matter, like your job, your house, your car. The sand is everything else -- the small stuff.
"If you put the sand into the jar first," he continued, "there is no room for the pebbles or the golf balls. The same goes for your life. If you spend all your time and energy on the small stuff, you will never have room for the things that are important to you. Pay attention to the things that are critical to your happiness. Play with your children. Take time to get medical checkups. Take your partner out dancing. Play another 18.
"There will always be time to go to work, clean the house, give a dinner party and fix the disposal. Take care of the golf balls first -- the things that really matter. Set your priorities. The rest is just sand."
One of the students raised her hand and inquired what the beer represented. The professor smiled. "I'm glad you asked. It just goes to show you that no matter how full your life may seem, there's always room for a couple of beers."
To bring it together with both solids and liquids.The professor then picked up a jar of pebbles and poured them into the jar. He shook the jar lightly. The pebbles, of course, rolled into the open spaces between the golf balls. He then asked the students again if the jar was full. They agreed it was.
The professor picked up a box of sand and poured it into the jar and of course the sand filled up everything else. He asked once more if the jar was full. The students responded with an unanimous yes.
The professor then produced two cans of beer from under the table and then proceeded to pour the entire contents into the jar, effectively filling the empty space between the grains of sand. The students laughed.
"Now," said the professor, as the laughter subsided, "I want you to recognize that this jar represents your life. The golf balls are the important things -- your family, your partner, your health, your children, your friends, your favorite passions -- things that if everything else was lost and only they remained, your life would still be full.
"The pebbles are the other things that matter, like your job, your house, your car. The sand is everything else -- the small stuff.
"If you put the sand into the jar first," he continued, "there is no room for the pebbles or the golf balls. The same goes for your life. If you spend all your time and energy on the small stuff, you will never have room for the things that are important to you. Pay attention to the things that are critical to your happiness. Play with your children. Take time to get medical checkups. Take your partner out dancing. Play another 18.
"There will always be time to go to work, clean the house, give a dinner party and fix the disposal. Take care of the golf balls first -- the things that really matter. Set your priorities. The rest is just sand."
One of the students raised her hand and inquired what the beer represented. The professor smiled. "I'm glad you asked. It just goes to show you that no matter how full your life may seem, there's always room for a couple of beers."
Is 11 early enough to learn about beer?
That suggests another nice demo: the "muesli effect" - half fill a container with something light and small such as polystyrene beads, then some heavy stones, then fill with more beads. Ask the kids where they think the stones will go if you shake the container. They should "float" to the top.
Simpo Two said:
Perhaps I'm out of step with modern teacher training, but if she is teaching this stuff, how come she doesn't know it?
Because she is a supply teacher, not a specialist science teacher. At present she is covering for a specialist science teacher on a and looking for some fun experiments to supplement the coursework that has been left for her. Ah right.
I used to enjoy working through Leonard de Vries' Book of Experiments http://www.amazon.co.uk/The-Book-Experiments-Leona... - might be worth getting.
I used to enjoy working through Leonard de Vries' Book of Experiments http://www.amazon.co.uk/The-Book-Experiments-Leona... - might be worth getting.
Eleven said:
Simpo Two said:
Perhaps I'm out of step with modern teacher training, but if she is teaching this stuff, how come she doesn't know it?
Because she is a supply teacher, not a specialist science teacher. 
RichB said:
e used to have a supply teacher who wore a powder blue crushed velvet mini skirt and black thigh length boots. can't remember what she was teaching though.
My missus is quite fit for a spoddy teacher, but the school she works for is an independent one and they wouldn't approve of anything other than business attire.Eleven said:
RichB said:
e used to have a supply teacher who wore a powder blue crushed velvet mini skirt and black thigh length boots. can't remember what she was teaching though.
My missus is quite fit for a spoddy teacher, but the school she works for is an independent one and they wouldn't approve of anything other than business attire.
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