A flask of water is connected to a powerful vacuum pump. When the pump is turned

Question

A flask of water is connected to a powerful vacuum pump. When the pump is turned on, the water begins to boil. After a few minutes, the same water begins to freeze. Eventually, the ice disappears. Explain what happens at each step A length of wire is placed on top of a block of ice. The ends of the extend over the edges of the ice, and a heavy weight is attached to end. It is found that the ice under the wire gradually melts, so the wire slowly moves through the ice block. At the time the water above the wire refreezes. With reference to the phase diagram of water, explain these phase changes

Explanation / Answer

Answer1.

When the vacuum pump is on, it removes all the air present in the system, thus air presssure decreases and boiling point of water also lowers down. HEnce water starts to boil.

After sometime of water boiling, there is some amount of heat from the water taken away and temp. of water cooles down, and when tempreture cools more, this Results freezing of water.

Answer2.

As given, wire is attached to the edges and placed over the ice block, a friction occures at the upper edge of the block and due to this heat generated. Thid results melting of ice and wire gets inserted inside the block thoroughly.

Simultaneously, the portion over the wire get free from friction and temp. gets lower at this point resulting again freezing of water above the wire.

hope this helped. thank you.

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