The energy involved in change of state
2 marks · EasyA student heats a solid and records its temperature every minute. Describe how the temperature readings would change if the student continues heating the substance until it has fully melted and then further increases the temperature.
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Also accept: At first, the temperature rises. Then, while the substance is melting, it stays the same. After all has melted, temperature rises again.
Common mistakes: Temperature only rises; ignores flat section.
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Marking points
B1 · 1 mark · Mentions temperature increases before melting.
B2 · 1 mark · Mentions temperature stays constant during melting and rises again after all melted.
Worked solution
The temperature increases until the substance begins to melt. While it is melting, the temperature stays the same. After melting is complete, the temperature of the liquid rises again as heating continues.