Question

Dr. Wong's assistant made the observations below while heating a sample of solid hydrogen. Using the data and observations in the table below, create a heating curve for hydrogen that Dr. Wong can reference during his laboratory testing. Be sure to include and label the following items in your heating curve:

Create temperature and time intervals that are appropriate for the data.
Don't start the temperature on the graph at 0 °C because the time intervals will be too large for the hydrogen data.
Label the melting and boiling points on the curve.
Label the three states and the two transition phases on the curve.

Heating data:
Time (Minutes) Observations
0:00 Hydrogen is a solid at −263 °C. Heat is added to sample.
2:43 Hydrogen begins to change into a liquid at −259 °C.
6:15 Temperature of the liquid begins to increase.
10:36 Hydrogen begins to form a gas at −253 °C.
14:01 Temperature of the gas begins to increase.
18:00 Final temperature of hydrogen gas is −245 °C.

Create a model of the atoms of a substance moving through the solid, liquid, and gas states. This can be a physical model using household or crafting items or a colorful diagram, illustration, or animation. You can be as creative as you want. Be sure to include and label the following items in your model:

the three states of matter
movement and spacing of molecules
loss or gain of kinetic energy and temperature
transfer of heat
breaking or building of intermolecular bonds
Include one paragraph to explain the movement of energy during phase transitions. View this student example using candy to help spark your own modeling ideas.

Answer 1

Based on the observations provided, we can create a heating curve for solid hydrogen:

Temperature (°C) | Time (minutes)
------------------------------------------
-263 | 0:00
-259 | 2:43 (melting point)
-253 | 10:36 (boiling point)
-245 | 18:00

The heating curve will have three distinct sections representing the three states of matter: solid, liquid, and gas. The time intervals can be determined based on the given data points.

On the curve, we would label:
1. Melting point (-259 °C): This is where hydrogen begins to change from a solid to a liquid state.
2. Boiling point (-253 °C): This is where hydrogen begins to change from a liquid to a gaseous state.
3. Solid phase: Labeled below the melting point.
4. Liquid phase: Between the melting and boiling points.
5. Gas phase: Above the boiling point.

Regarding the movement of energy during phase transitions, energy is either gained or lost during these transitions without affecting temperature. When transitioning from a solid to a liquid (melting), heat energy is absorbed by the substance without changing its temperature until all solid has converted into liquid form. Similarly, when transitioning from a liquid to a gas (boiling), heat energy is absorbed without causing an increase in temperature until all liquid has converted into gas form.

During these phase transitions, intermolecular bonds are broken or formed. In the case of hydrogen, as it melts, some of its intermolecular bonds break allowing molecules to move more freely while still being relatively close together in comparison to gases. As it boils and becomes a gas, most of its intermolecular bonds break, and the molecules move apart with increased kinetic energy.

I hope this explanation helps!