This experiment can be used in so many different units because water is such an integral part of life on this planet. For example, it could be used in an earth science unit dealing with the properties of water and their effects on weather or in a biology unit dealing with the components of the body, or in a chemistry unit dealing with boiling points and heat capacity. The experiment has a fairly basic procedure but it does require a review of safety precautions and how to use a thermometer. Furthermore, it requires an understanding of making a data table and of graphing.

As an introduction, ask the students to think of all the uses of water that they have seen in their lives. Write their answers on the board. Tell them that this experiment will show how many of those uses are based on a property of water called high heat capacity. Ask the students to try to figure out the definition of "high heat capacity" based on the individual words (i.e. -- maybe they'll see that it sounds like "capable of holding heat.") Then explain the formal definition: heat capacity is the amount of heat required to raise the temperature of a substance by a certain number of degrees. Explain to the students how in this lab, they will heat the water until it boils. Ask them to think of what the graph of temperature vs. time would look like given that water has a high heat capacity (i.e. -- if water has a high heat capacity, it needs to absorb a lot of heat before its temperature rises. Therefore, it requires a relatively long time to boil). Finally explain to the students that rubbing alcohol will be used as a comparison to the water. Ask the students to think about what the difference between alcohol and water will be.

boiling point

heat capacity

high heat capacity

low heat capacity

temperature

absorb

for each group of students:

• -hot plate
• -(2) 400 ml beakers
• -graduated cylinder
• -200 ml of water
• -200 ml of isopropyl alcohol (rubbing alcohol)
• -(2) thermometers
• -watch or clock with second hand
• -goggles
• -paper towel or beaker holder to remove the hot beaker from hot plate

Divide class into small groups to perform the following steps:

1. 1.Preheat hot plate by turning to "high".
2. 2.One student fills one of the beakers with the 200-ml of water, while another student fills the other beaker with the 200-ml of alcohol.
3. 3.Place a thermometer in each beaker and record the initial temperature of each liquid (time = 0 minutes).
4. 4.One student places both beakers on the hot plate simultaneously while another student begins the timer.
5. 5.The timer will announce to the group when each minute passes. At each announced minute one student will read the temperatures of both liquids while another student records the temperatures and time in an appropriate data table form.
6. 6.Once a liquid boils, remove it from the hot plate (BE CAREFUL -- HOT!!), but continue to record temperatures every minute for the other liquid that has not boiled yet.
7. 7.Remove this liquid when it finally boils (BE CAREFUL -- HOT!!)

Have each group compare the temperature and time of each solution and discuss possible meanings of those results.

- As a whole class, discuss conclusions that can be drawn from the data.

- Have each student submit a lab report including a graph of their results.

Individualized extra help may be necessary for those students who can't form a conclusion or whose graph does not match the results.

Now that students have demonstrated for themselves the high heat capacity of water, they can understand how this property makes water such an important liquid for all forms of life. For example, since our bodies are about 60% water, we are able to maintain a relatively stable internal temperature despite greater variations in temperatures outside. It is therefore, important to drink water. Connections then can be made to the students' lives by noting the importance of hydrating themselves after exercise (a game of basketball for example) since a lot of water is lost in the form of sweat.

Another application of the high heat capacity of water is that it shows why the temperatures of cities located near large bodies of water have relatively moderate temperatures (i.e. -- the difference between the high temperature and low temperature are not that great). Students could collect this data from newspapers and prove this phenomenon for themselves. The Internet also provides information about a particular U.S. city's temperatures in the past. It also gives up to date information about international cities. The address is: http://www.intellicast.com/. To find a U.S. city's information, click on the "USA" at top. Then chose a city and click on "city almanac" on the left-hand side. To find the current temperature of an international city, click on "world" at top, then click on a particular city from the list.

Both of these examples then show how important it is to help the environment and ourselves by conserving water -- e.g. turning the water off when brushing teeth or washing dishes -- and keeping our lakes and oceans free from litter and pollution.

SCIENCE CONTENT STANDARD #1: NATURE OF SCIENCE

This experiment satisfies Benchmark 1 for grades 5-8: "design, modify, and conduct an investigation through testing, revising, and occasionally discarding ideas, all of which lead to a better understanding of how things work." It also satisfies Benchmark 3 for grades 5-8: "collect and summarize data from an experiment and interpret the results in terms of the data."

SCIENCE CONTENT STANDARD #2: PHYSICAL SETTING

This standard states that student should "have a basic knowledge of the overall structure of the universe, the physical principles on which it runs, and the processes that shape the earth." This experiment allows the students to better understand their physical surroundings especially by learning of the phenomenon mentioned in the "Extensions" section (i.e. large bodies of water moderating temperatures).

SCIENCE CONTENT STANDARD #3: LIVING ENVIRONMENT

Benchmark 7 of this standard asks students to "describe how all organisms maintain a relatively stable internal environment while living in a constantly changing external environment." This experiment shows how water plays a large role in maintaining this stable environment.

SCIENCE CONTENT STANDARD #4: HUMAN ORGANISM

Benchmark 2 for grades K-4 states that students should be able to "describe how people need water, food, waste removal, and a particular range of temperatures." This experiment allows them to see why humans need water.

SCIENCE CONTENT STANDARD #5: DESIGNED WORLD

The introduction to the Philadelphia Science Content Standards states that students should understand "the impact of science and technology on society with a focus on populations, resources, and the environment". This experiment helps the-students to see how valuable water is and, therefore, why we need to be concerned about protecting it from any of the negative effects of science and technology.

Since water is so integral to almost anything we do, this experiment could be used in almost any unit. For example, it would work great on a chemistry unit dealing with the heat capacities of various substances, an earth science unit on water or weather, a biology unit on the human body. It also incorporates many mathematical skills such as graphing.