Fig. 1.1 shows a beaker of water being heated. Bubbles of steam form throughout the liquid and rise to the surface. Which statement correctly describes what...
Question 1 Report
Fig. 1.1 shows a beaker of water being heated. Bubbles of steam form throughout the liquid and rise to the surface.
Which statement correctly describes what is happening?
Answer Details
Bubbles forming throughout the body of the liquid and rising to the surface is the defining characteristic of boiling. During boiling, the liquid has reached its boiling point and is changing state from liquid to gas (steam) at locations throughout the liquid, not just at the surface.
Evaporation, by contrast, occurs only at the surface of a liquid and happens at temperatures below the boiling point. The bubbles described in this question form deep within the liquid, which rules out surface-only evaporation. They also cannot be air bubbles: dissolved air produces tiny bubbles when a liquid is first warmed, but the large bubbles of steam described here indicate a full change of state.
Condensation is the reverse process (gas turning to liquid) and does not produce bubbles rising through a liquid. The correct description is that the water is boiling and changing to steam throughout the liquid.
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