Absolute Zero Demonstrator (Sabiha Dalal)

Author

Sabiha Dalal, 6th Grade Special Education Teacher at Sepulveda Middle School

Principles

1.) Demonstrates that decreasing pressure correlates with decreasing temperature.

(Pressure vs. Temperature)

Standards

Grade 8: Focus on Physical Science - Investigation and Experimentation

9.) Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will:

a.) Plan and conduct scientific investigations to test a hypothesis.

b.) Recognize the slope of the linear graph as the constant in the relationship y=kx an apply this

principle in interpreting the graphs constructed from data.

e.) Construct appropriate graphs from data and develop quantitative statements about the

relationships between variables.

Chemistry - Grades 9-12, Gases and Their Properties

4.) The kinetic molecular theory describes the motion of atoms and molecules and explains the properties of gases. As a basis for understanding this concept:

c.) Students know how to apply the gas laws to relations between the pressure, temperature,

and volume of any amount of an ideal gas or any mixture of an ideal gas.

f.) Students know there is no temperature lower than 0 Kelvin.

Materials needed

1.) Absolute Zero Device Apparatus or Demonstrator

2.) Thermometer (3)

3.) Dry ice

4.) Rubbing alcohol

5.) Bucket or pot filled with water (room temperature)

6.) Bunsen burner or stove

7.) Bucket or pot of ice water

8.) Pliers

Procedure

Boiling Water

1.) Boil a pot of water and after turning off the stove, submerge the absolute zero apparatus in

the boiling water.

2.) Open the valve to equalize the pressure to atmospheric (parallel valve).

(It helps to use pliers)

3.) Next, close the valve (perpendicular handle). It helps to use pliers.

4.) Insert the thermometer to measure the temperature of the water.

5.) Wait for both the apparatus and temperature to stabilize and record your results for both pressure and temperature.

6.) Record your results in the table.

Dry Ice Mixture

1.) In a large bowl or pot add dry ice and rubbing alcohol.

2.) Next, immerse the thermometer and absolute zero apparatus in the solution.

3.) Record your results in the table.

Room Temperature

1.) Add room temperature water to a large pot or bowl.

2.) Insert the thermometer and absolute zero apparatus.

3.) Record your results in the table.

Ice Water

1.) Add ice to a large bowl or pot, with just a little bit of water.

2.) Insert the thermometer and absolute zero apparatus.

3.) Record your results in the table.

*You can test various other solutions, such as salt water and ice and tepid water; following similar steps.

Helpful Tips:

a.) Have a partner help you, as extra hands can stabilize the equipment.

b.) Use pliers to adjust pressure valve

c.) Immerse the entire bulb in the solution.

d.) Allow enough wait time for the thermometer and device to stabilize before recording your data.

e.) A minimum of 2 trials need to be done so that you have two sets of data to graph.

Explanation

The absolute zero apparatus demonstrates the relationship between pressure and temperature. Pressure is caused by the collisions of gas particles. When the temperature is lowered the particles move more slowly and the pressure falls. Absolute zero is the temperature at which matter cannot move.

Questions

1. Using your data table/graph, find the the % difference between the experimental absolute zero and the theoretical absolute zero, -273 C.

2. Identify and explain several factors that might account for differences between the observed and accepted values.

3. Explain how the apparatus and the class's experimental graph could be used to determine the temperature of a swimming pool without a thermometer.

Answers:

1.) % difference = 100% x (-273 - X) / (-273)

2.) Inaccurate readings for pressure and temperature, not waiting long enough for the

temperature to equalize, percentage of substances used (dry ice, salt, alcohol, etc.)

3.) Measure the pressure with the absolute zero apparatus by immersing the bulb in the water

and determine the temperature using the temperature vs. pressure graph.

Sample Chart

Everyday examples of the principles illustrated

Laws of Thermodynamics, entrophy, computers that need cooling

Movies

References

Cost of demonstrator

Absolute Zero

Experiments