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Do air particles change size or shape when air is removed from a flask?
No.
What is the hole in the rubber stopper for?
To let air go thru
How does a thermos flask keeps a hot liquid hot and a cold liquid cold?
A thermos is able to do what it does by using a several of physical and material properties to keep our hot chocolate hot and our ice tea icy. A thermos has an inner container made of glass. This container is really like one bottle inside of another bottle and sealed at the ends by melting the edges together. The air is removed out from the space between the two bottles to produce a vacuum, which is not a good conductor of heat and does a good job at slowing down the movement of heat. To slow down the other heat they coat the facing surfaces of the glass bottles with a silvery coating (like a mirror). This reflects the heat and helps slow down any losses that might get that way. They use a material like cork or rubber to make the bottle stopper and anything else that might touch the outside surface of the glass container. These materials are bad conductors of heat and slow down the heat loss. What's left is what we can see on the outside which can be metal or plastic and is the covering for the glass bottles. The idea here (with the thermos) is to slow down the movement of heat from one place to the other. So if you have hot stuff in the thermos or cold stuff in the thermos, the end result is the same. Keep heat from moving to where you don't want it to go for as long as possible. NB It's worth mentioning that modern vacuum flasks (Thermos being a trade name) are made almost entirely of stainless steel, inside and out - it doesn't shatter and is naturally reflective, although not polished to a mirror shine when used as a flask inner. Modern stoppers are also made of plastic.
Why was it important to determine the mass of the air in the flask?
to make happy
How did Louis Pasteur experiment differ from lazzaro spallanzani experiment?
Instead of sealing the flask in the experimental group after boiling, Pasteur used a flask with a curved neck, which allowed air inside and outside the flask to mix but prevented microorganisms from entering the body of the flask.
How does a thermos flask reduce conduction?
There is air between the inside and outside of the flask.
How a thermos flask minimizes energy losses from convection?
As the flask is closed air tight, no convection current is possible.
What is the scientific principle of making thermos flask?
thermos flask actually works on the principle of insulator. air is trapped between 2 walls of the flask. air being a bad conductor of heat traps it between the walls. this keeps the material in the flask hot for a longer period.add. Actually, usually there is a vacuum between the two walls of the flask, for this is a better insulator than air. hence the name 'vacuum flask'.
Why your vacuum flask cannot maintain the cold anymore?
There could be a crack or leakage that allows air to flow in or out of the flask. It may be time to replace the flask with a new one.
How does a tight fitting plastic stopper on a flask minimise heat transfer?
It prevents heat transfer by convection as it prevents contact between the surrounding air and air inside the flask. It prevents heat transfer by conduction as it is a poor conductor of heat.
Will snowman with a coat or without melts first?
Without a coat the coat keeps the cold air in, like a thermos flask we learnt this in year 3....
How can the structure of the vacuum flask minimise energy transfer by conduction convection and radiation?
The flask has a double wall, with no air between the two walls (vacuum)- conduction. The walls are highly reflective silver- radiation. the flask has a small beck that is closed by a stopper or cap-convection.
How is conduction prevented in a thermos flask?
There are many ways this is done. It can be done by having a double walled thermos with either air, an insulator, or a vacuum between. A vacuum will prevent all conduction except where the two walls touch but requires stronger materials.
How the thermos flask prevents heat loss by conduction?
There is a dead air space between the liner of the thermos and the outside. This space acts as insulation preventing conduction. In a really good thermos, or Dewar flask, the space is actually a vacuum. Vacuum is an even better insulator than air is, since heat doesn't conduct across a vacuum at all.
How does thermos flask maintain the temperature of the object inside it?
The flask makes use of heavy insulation, either by vaccum, air cushion or just filled with very poor heat conductors to slow the heat loss from a hot drink or warming from the enviroment.
What thermos flask prevent loss or gain of heat by?
Thermos Flask prevent loss or gain of heat by separating the internal layer and the external layer with a vacuum (absence of air molecules). Heat is usually transferred through different media (air molecules and other molecules). Without these media, heat can't pass from one place to another, except for radiation which doesn't need any media (it can travel through vacuum)
What is the principal behind a thermos flask works?
the thermal conductivity of certain materials (e.g air)is low. This makes exchange of heat between the inside and the surroundings difficult, thus allowing temperature to be mantained.
