A tight lid glass jar has several lumps of ice, after some time water droplets form. Where did it come from?
A teacher has a glass jar with a tight fitting lid. She unscrews the lid, puts serveral lumps of ice into the jar and then seals the lid tightly. After a short time, water droplets form on the outside of the jar. She asks the class to explain how the water comes to be there. Several pupils say that it comes from the ice.
pricklycharacter
on February 8th, 2012
Water droplets in the warmer air condense on the colder surface of the jar.
Aravis
on February 8th, 2012
condensation
Solitarygrowth
on February 8th, 2012
condensation sweetie
Connie
on February 8th, 2012
No. It came from water in the chilled air next to the jar.
DarkDesire
on February 8th, 2012
Condensation…the glass jar is colder than the surrounding air. As a result, the glass “pulls” moisture from the outside air onto it’s outer surface. The moisture condenses, and droplets form.
If this experiment was performed in space, it wouldn’t work.
Casper
on February 8th, 2012
Condensation occurs where moist air comes into contact with air, or a surface, which is at a lower temperature.
Air contains water vapour in varying quantities, its capacity to do so is related to its temperature – warm air holds more moisture than cold air. When moist air comes into contact with either colder air or a colder surface, the air is unable to retain the same amount of moisture and the water is released to form condensation in the air or on the surface.
Condensation is generally noticeable where it forms on non-absorbent surfaces (i.e. windows or tiles) but it can form on any surface and it may not be noticed until mould growth or rotting of material occurs.
FootballFan
on February 8th, 2012
They come from the air outside of the jar.
When you put an ice in the jar and seal the cap, none of the water from the ice can escape. However, the cold (or rather, lack of heat) from ice conducts to the ice then to inside of the glass, then to outside of the glass.
The air around the jar contain moisure. When it comes in contact with the outside of the glass (which is cold), it condenses into water droplets.
Colder the temperature, less water the air can hold. The difference as a result of cooling becomes water droplets.
Style
on February 8th, 2012
Atmospheric air contains water vapour (Humidity of the air).
The ice in the jar cools the outside of the glass by removing heat from it.
The ‘coldness’ causes the air around the jar to cool to a point where, the water vapour in the air in contact with the glass, comes down in temperature to the ‘Dew Point’ of the water vapour and it condenses (liquefies) on the cold surface.
(In the early morning in summer, particularly, when it’s quite cool outside, dew forms as droplets of water on the grass and other cool areas .. hence…’Dew Point’.)