Question

heating curve homework
name
date per
answer the following using the above heating curve

1. what is the melting temperature of the above substance?
2. what is the freezing temperature of the above substance?
3. what is the boiling temperature of the above substance?
4. the part of the graph labeled \e\ represents temperatures at which gas is being heated. describe what is happening for each of the other lettered sections of the graph:

a.
b.
c.
d.

1. in which section of the graph are atoms moving the least?
2. in which section of the graph is this substance all liquid?

Explanation:

Step1: Analyze the heating curve

A heating curve shows the phase changes of a substance as energy is added. The flat sections represent phase changes (melting or boiling) where temperature remains constant. The sloped sections represent heating of a single phase.

Step2: Determine melting, freezing, and boiling points

• Melting occurs when a solid turns to liquid. The temperature during melting is constant. From the graph, section \(b\) is the melting phase. The temperature at this flat - section is \(5^{\circ}C\).
• Freezing is the reverse of melting. For a pure substance, the freezing temperature is the same as the melting temperature. So, it is \(5^{\circ}C\).
• Boiling occurs when a liquid turns to gas. Section \(d\) is the boiling phase. The temperature at this flat - section is \(15^{\circ}C\).

Step3: Describe each section

• Section \(a\): The substance is in the solid phase. As energy is added, the temperature of the solid increases.
• Section \(b\): The solid is melting. Energy is used to break the intermolecular forces in the solid, and the temperature remains constant.
• Section \(c\): The substance is in the liquid phase. As energy is added, the temperature of the liquid increases.
• Section \(d\): The liquid is boiling. Energy is used to convert the liquid to gas (overcome intermolecular forces in the liquid), and the temperature remains constant.

Step4: Determine atomic motion

Atoms move the least in the solid phase. Section \(a\) is the solid phase.

Step5: Identify the liquid - only section

Section \(c\) is the only section where the substance is entirely in the liquid phase.

Answer:

1. \(5^{\circ}C\)
2. \(5^{\circ}C\)
3. \(15^{\circ}C\)

4.

• a. Solid is being heated.
• b. Solid is melting.
• c. Liquid is being heated.
• d. Liquid is boiling.

1. \(a\)
2. \(c\)