Beacon Lesson Plan Library

What Is the Freezing Point?

Jeri Martin

Description

How does a liquid change to a solid? Students will remove heat energy and determine how it causes a phase change.

Objectives

The student understands that decreasing the average motion of the particles decreases the temperature.

The student knows that the average kinetic energy of the atoms or molecules of different objects varies with their temperature.

The student understands that changes in energy cause phase changes.

The student uses appropriate procedures for safety in the classroom, home, and community.

Materials

(per group of 4 students)
- 250 mL beaker (4)
- 1000 mL beaker (1)
- #2 test tubes (4)
- Test tube rack (1)
- Crushed ice (enough to fill a 1000 mL beaker)
- Celsius, red alcohol thermometers (4)
- 3 oz. Plastic cup (1)
- Rock salt (50 grams)
- Antifreeze (30 mL)
- Water (30 mL)
- Stopwatch

(per student)
- Graph paper
- Colored pencils (1 red and 1 blue)

(per class)
- ice chest
- plastic bucket

Preparations

1. Make copies of the K W L chart, Freezing Point Lab Rubrics and Freezing Point Lab

2. Prepare equipment for lab activity. Make sure you have enough items so that no more than four students are working together.

3. Gather materials

4. Checklist of items you may need to purchase:
_____ Ice
_____ Cups
_____ Rock salt
_____ Antifreeze

Procedures

DAY 1
1. Give students a copy of the Freezing Point Rubrics. (See copy in Associated File)

2. Give students a copy of the K W L chart for Phase Changes. (See copy in Associated File)

3. Discuss with students the K (what do you know) and W (what do you want to know) from the chart.

4. Give students a copy of the Freezing Point Lab (See copy in Associated File). Review the procedures and set up the graphs.


DAY 2
5. Freezing Point Lab - Students complete lab, graphing and turn in.

6. Have students complete the L section of their K W L chart and turn in.

Assessments

The Freezing Point rubric is marked as students go through this activity. The K W L chart and Freezing Point Lab will be collected and assessed.

Extensions

1. Repeating the lab, but using other liquids instead of the water and antifreeze can extend the Freezing Point Lab.
2. The procedures could be modified to allow it to be used as a cooperative group activity for ESE/ESOL students or if there are not enough supplies for each student to have their own individual set. A group of four students could set up the materials at the front of the room and have the other students record the temperature readings as they call them out every 30 seconds. Also, the time could be extended to only taking temperature readings every minute.

Web Links

Web supplement for What is the Freezing Point?
Phase changes of Water

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