Question

section 5: phase change graph
use the graph below to answer the following questions

1. using the graph, what happens to temperature during a phase change?
2. at what temperature does this substance melt?

at what temperature does this substance boil?

1. make a claim as to what substance this graph shows the phase change of.
2. does it take more energy to melt this substance or to make it evaporate? what evidence from the graph tells you this?

Explanation:

Step1: Analyze the phase - change graph

In a phase - change graph, during a phase change (like melting or boiling), the heat is used for breaking the intermolecular forces rather than increasing the temperature.

Step2: Identify melting and boiling points

The flat part of the graph during the melting process gives the melting temperature. The flat part during the boiling process gives the boiling temperature.

Step3: Compare the lengths of the flat parts for energy comparison

The longer the flat part (where heat is absorbed without a temperature change) in the graph, the more energy is required for that phase change.

Answer:

1. During a phase change, the temperature remains constant.
2. The substance melts at \(0^{\circ}C\) and boils at \(100^{\circ}C\).
3. This graph shows the phase - change of water. Because water has a melting point of \(0^{\circ}C\) and a boiling point of \(100^{\circ}C\) under standard atmospheric pressure.
4. It takes more energy to make it evaporate. Evidence: The flat part of the graph (representing heat absorption without a temperature change) during boiling is longer than that during melting.