an aluminum bar was first placed in liquid nitrogen and then in water. When the bar was placed in the water, it formed ice. What caused it to form ice?
2007-07-15 16:48:21 · 5 answers · asked by lola 1 in Science & Mathematics ➔ Physics
Remember that when two objects touch each other, heat will always flow out of the hotter object, into the colder object.
So, you have liquid nitrogen (extremely cold). The aluminum bar is placed into the liquid nitrogen, so a lot of heat flows out of the bar and into the nitrogen. The bar is now extremely cold.
When the very cold aluminum bar is placed in water, the bar has a much lower temperature than the water. Therefore, heat flows out of the water, into the bar. The bar's temperature increases, and the water's temperature decreases, until they are the same temperature. However, in your problem, the water loses so much heat that its temperature drops below 0 Celsius (water's freezing point), so it turns to ice.
2007-07-15 16:57:38 · answer #1 · answered by lithiumdeuteride 7 · 1⤊ 1⤋
Liquid nitrogen is in liquid form at very low temperatures- when the rod was stuck in the liquid nitrogen, it got REALLY cold, and then when it was placed in the water, the water transferred energy, in the form of heat, to the rod, thus losing enough energy to drop its temperature to zero degrees Celsius and complete a phase transition (liquid to ice) while simultaneously warming up the rod. All of the energy that it took to change the temperature and phase of the water is the energy that went into the rod.
Does this help?
2007-07-15 23:58:08 · answer #2 · answered by Anonymous · 1⤊ 1⤋
I think that liquid nitrogen made the bar cooler, which in turn made the water into ice.
2007-07-15 23:56:42 · answer #3 · answered by renolibrado 2 · 0⤊ 2⤋
the liquid nitrogen boils at like -300F, meaning its in liquid form at an even lower temperature. it will bring down the temperature of anything it come into contact with. in fact if you were to put your hand in it, it would instantly freeze and shatter if you hit it on something.The aluminum bar having been brought down to -300C will freeze water.
2007-07-15 23:59:16 · answer #4 · answered by Anonymous · 2⤊ 1⤋
Energy transfer from the cooled Aluminum bar to the water and from the water to the cooled bar... Thermal exchange... nothing special there. Normally two opposite systems will tend to equilibrate themselves by losing their initial entropy.
2007-07-15 23:57:06 · answer #5 · answered by Jedi squirrels 5 · 0⤊ 2⤋