Evaporation and Boiling
Chemistry ⇒ States of Matter
Evaporation and Boiling starts at 7 and continues till grade 12.
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See sample questions for grade 10
A beaker contains 100 mL of water at 25°C. If the temperature is increased to 50°C, what happens to the rate of evaporation?
A puddle of water dries up faster on a windy day than on a calm day. Explain why.
A student observes that petrol evaporates faster than water. Give a reason for this observation.
Calculate the boiling point of water at an atmospheric pressure of 80 kPa, given that the normal boiling point at 101.3 kPa is 100°C. (Assume the boiling point decreases by about 1°C for every 2.7 kPa drop in pressure.)
Describe two differences between evaporation and boiling.
Describe what happens to the temperature of a liquid as it boils.
Explain why a liquid feels cooler when it evaporates from your skin.
Explain why it is dangerous to heat a closed container of liquid until it boils.
Explain why sweating helps to cool the human body.
If the atmospheric pressure decreases, what happens to the boiling point of a liquid?
State one reason why clothes dry faster on a hot, dry day than on a cold, humid day.
What is the main difference between vaporization and evaporation?
Why does water boil at a lower temperature on a mountain than at sea level?
A liquid is heated in an open vessel at a high altitude where atmospheric pressure is much lower than at sea level. Predict and explain how the boiling point of the liquid will change compared to its boiling point at sea level.
A sealed container contains two liquids: ethanol (boiling point 78°C) and water (boiling point 100°C). If the container is heated to 85°C, which liquid will boil and why?
Calculate the amount of heat required to completely vaporize 200 g of water at 100°C. (Latent heat of vaporization of water = 2260 kJ/kg)
Describe how humidity affects the rate of evaporation and explain the underlying reason.
Explain why boiling water at the top of a mountain takes longer to cook food than at sea level, even though the water is boiling.
Explain why the boiling point of a liquid remains constant even though heat continues to be supplied during boiling.
