NCERT Solution for Class 9 Science Chapter 1
Matter in Our Surroundings
NCERT Books for Session 2022-2023
CBSE Board and UP Board
Intext Questions
Page No-10
Questions No-3
Why does our palm feel cold when we put some acetone or petrol or perfume on it?
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When we put some acetone or petrol or perfume on our palm, it evaporates. During evaporation, particles of the liquid absorb energy from the surrounding or the surface of the palm to compensate for the loss of energy, making the surroundings cool. Hence, our palm feels cold when we put some acetone or petrol or perfume on it.
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Acetone, petrol or perfume evaporate when they come into contact with air. The evaporation causes cooling sensation in our hands.
– Refreshing Coolness: Acetone, petrol, and perfume create a sensation of coolness when in contact with the skin due to their rapid evaporation.
– Low Boiling Points: These substances have low boiling points, causing them to transition swiftly from a liquid to a gas upon contact with the warmth of the skin.
– Heat Absorption: Evaporation of these substances is an endothermic process, meaning it absorbs heat from the skin to convert into a gas, leading to a decrease in skin temperature.
– Intensified Evaporation: Their high volatility further amplifies the speed of evaporation, enhancing the cooling effect experienced on the skin.
– Caution Needed: Prolonged contact with these substances can potentially cause skin irritation or dryness, necessitating care and moderation in their usage to avoid adverse effects.