Table 2.1 lists four changes of state. The names of the changes have been left blank. change of state name of the change solid → liquid liquid → gas gas → l...
Question 1 Report
Table 2.1 lists four changes of state. The names of the changes have been left blank.
| change of state | name of the change |
|---|---|
| solid → liquid | |
| liquid → gas | |
| gas → liquid | |
| liquid → solid |
(a) Complete Table 2.1 by writing the name of each of the four changes of state. [4]
(b) Name the change of state in which a solid turns directly into a gas without first becoming a liquid. [1]
(c) State the name given to the fixed temperature at which a pure solid turns into a liquid. [1]
(d) Name the process by which a liquid slowly turns into a gas from its surface at temperatures below its boiling point. [1]
Answer Details
This question tests the names of the changes of state and the two surface-versus-bulk processes (sublimation and evaporation). Learn each change as a one-word name for a specific direction between two states.
(a) [4] The completed table is:
| change of state | name of the change |
|---|---|
| solid → liquid | melting |
| liquid → gas | boiling (evaporation accepted) |
| gas → liquid | condensation |
| liquid → solid | freezing (solidifying accepted) |
Each name earns [1]. Note the direction carefully: melting and freezing are opposites, as are boiling and condensation.
(b) [1] A solid turning directly into a gas without becoming a liquid is sublimation.
(c) [1] The fixed temperature at which a pure solid turns to liquid is its melting point.
(d) [1] A liquid slowly turning to gas from its surface below the boiling point is evaporation. This differs from boiling, which happens throughout the liquid at a fixed temperature.
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