Question

why does our palm feel cold when we put some acetone or petrol or perfume on it? why are we able to sip hot tea or milk faster from a saucer rather than a cup​

Answer 1

Answer:

(i) Evaporation is a surface phenomenon. When we pour acetone, petrol or perfume on our hand, the liquid evaporates by absorbing the heat from the surface of our palm, hence making it cooler.

(ii) Evaporation causes cooling. A saucer has larger surface area than cup, hence evaporation happens faster and the tea is cooled down faster.

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Answer 2

Explanation:

QUESTION:

why does our palm feel cold when we put some acetone or petrol or perfume on it? why are we able to sip hot tea or milk faster from a saucer rather than a cup?

ANSWER:

We feel cold on our palms AS the acetone has low boiling point and as it evaporates it takes away the heat from our palms via latent heat of fusion.

We are able to sip hot tea from a saucer better as the saucer has larger surface area and so Evaporation rate is more, so the steam evaporates faster and hence it becomes cool.

EVAPORATION:

The process of conversion of Liquid state in to its vapour state is Evaporation

LATENT HEAT:

As it tells the hidden heat taken from surroundings is latent heat.

CONDITIONS FOR EVAPORATION

• Large surface area
• Less humidity
• More temperature
• Less pressure.