Title: Exploring endothermic and exothermic reactions using gas

Principle(s) Investigated: List all principles that apply to this activity.

Exothermic Reaction, Endothermic Reaction, the importance of knowing differentiating harmless and flammable or harmful chemical reactions.

Standards : Past in the appropriate California content standards.

Grade 8

Standard 5. c. Students know chemical reactions usually liberate heat or absorb heat.

Students will identify when molecules interact and the temperature decrease, it is an endothermic reaction.

Students will identify when molecules interact and the temperature increases, it is an exothermic reaction.

Students will recognize that gasses are different, some are dangerous and some are not.

Materials: Include a list of materials and sources from which they may be obtained.

Carbon dioxide maker

- flask

- balloon

- baking soda

- vinegar

- stationary flame ie Bunsen burner

- wooden dowel with a clip to hold balloon

- thermometer

Hydrogen balloon explosion

- flask

- balloon

- sodium hydroxide

- water

- aluminum foil

- stationary flame

- gloves

- wooden dowel with a clip to hold balloon

Procedure: Give a detailed explanation of the procedure and include diagrams if possible.

Check the temperature of the vinegar baking soda mix. (Quick write about the temperature increase or decrease)

1. Put vinegar in a beaker

2. Check the temperature with thermometer

3. Add baking soda

4. Check temperature again

Explain this is an endothermic reaction (heat absorption)

Carbon Dioxide Balloon

1 Put 2-3 tablespoons of baking soda in a balloon using a powder funnel

2. Put approximately 100ml of vinegar in a flask

3. Put the balloon over the lip of the flask without putting the baking soda in, when the lip is secure pour in the baking soda slowly and let the balloon fills up. When it is at your desired size take the balloon off of the flask and tie it. (ask students what will happen if I put a flame to it, quick write)

4. Light a flame to the balloon.

Sodium Hydroxide Balloon Explosion

1. Pour approximately 300-400 ml of H2O in a flask

2. Slowly add approximately 2-3 tablespoons of NaOH

3. Let the solution dissolve for a minute or two then add the strips of aluminum to the mixture. Let it dissolve for approximately 30 seconds. (can let students feel the heat build up) We will not use a thermometer to measure this temperature. Will explain this is an exothermic reaction ( release of heat). The students will be able to witness the heat.

4. with gloves and goggles on put balloon over the lip of the flask and let the hydrogen fill the balloon.

5. Show class. (quick write) Ask what will happen with a flame is put to it. put flame to it.

When finished burning each balloon, explain that some combinations are dangerous and some are not. Explain the importance of being informed, safe, and cautious when dealing with chemical reactions.

Data Table

https://docs.google.com/spreadsheet/ccc?key=0AgtFivpcbpgGdERmYzdiM21Sem1Pay1Rc0JOYVhFVGc#gid=0

Student prior knowledge: What prior concepts do students need to understand this activity?

Students should know about atoms and that when atoms combine they make molecules, and that these molecules can be combined, i.e hydrogen and oxygen make water.

Students need to know that there are elements and when elements combined there are different reactions. Students will need to know about that some combinations will respond with (energy) heat absorption or by releasing (energy) heat. Students will need to know some basic elements from the periodic table, and basic gases.

Explanation: Give a thorough explanation of the experiment or demonstration. Your explanation should be written to give your fellow teachers a solid understanding and include greater detail than what you might provide for your secondary students. Make certain to include equations whenever pertinent.

This experiment is to demonstrate the principles of endothermic and exothermic reactions and how energy is released or absorbed through chemical reactions. Students will read about both principles, but this is an opportunity for the students to have a kinesthetic and visual experience with these concepts and the use of said SDAIE strategies. This is an introduction into a subject that will explore a deeper understanding that it takes more energy to break chemical bonds in an endothermic reaction, an in an exothermic reaction it takes more energy to form bonds. The use of videos will be used to further develop the concept and make the material more relatable. As everyday applications of these reactions are mentioned, it allows for the concept to be useful information for the students.

Students will also be made aware of the possible dangers of mixing chemicals so they do not haphazardly try this on their own without appropriate knowledge and supervision.

Questions & Answers: Give three thought-provoking questions and provide detailed answers.

1. How is having a cup of hot tea and a cup of ice water that after a period of time end up with the same temperature analogous to endothermic and exothermic reactions?

The ice water becoming room temperature is analogous to an endothermic reaction as the ice absorbs heat and begins to melt. The hot tea is analogous to exothermic reaction as it gives off heat (releases heat).

2. How is sweating both an endothermic and exothermic reactions?

Because the body is releasing heat in the form of sweat it is exothermic, as sweat evaporates and cools the body it is endothermic.

3. Since we experimented endothermic and exothermic reactions using Carbon Dioxide and Hydrogen, by observation how are Carbon Dioxide and Hydrogen similar? How are they different?

The both are invisible gases, colorless, and odorless

Hydrogen is volatile, flammable lighter than air. Carbon Dioxide is not flammable, less reactive, and heavier than air.

Questions to be asked throughout the demonstration.

According to what we know about endothermic and exothermic reactions what type of reaction filled the carbon dioxide balloon, and what type or reaction filled the hydrogen balloon, explain?

Carbon Dioxide Balloon: The reaction was endothermic, carbon dioxide was released and the temperature of the vinegar cooled

Sodium Hydroxide: The reaction was exothermic, hydrogen was released, and the temperature increased greatly

What will the effect be of the chemicals in the balloon when exposed to heat and oxygen for balloon A. and balloon B.?

Hydrogen is a highly flammable gas and will cause an explosion, and carbon dioxide is non flammable and will not cause an explosion. This is important to be aware that gases are complex and it is important to be safe and informed when dealing with these elements. This is the safety portion of learning about gases and reactions

What’s another way to fill up a balloon with CO2?

Blow into the balloon!

Applications to Everyday Life: Explain (don't just list) three instances where this principle can be used to explain other phenomenon.

1) One example of an exothermic everyday life application is when it’s cold and you need to warm up.

Hand Warmers. Many hand warmers contain elements that when shaken, twisted, or other means of manipulation cause an exothermic reaction releasing heat that can last anywhere from 30 minutes to 8 hours. They also come with warnings in case of exposure or over heating, it depends on the brand. Here is one:

Little Hotties http://www.littlehottieswarmers.com/precautions.php

“Precautions

Use Little Hotties Warmers as directed on the package. Failure to follow the precautions listed below may result in serious injuries or burns.

1. Exposure of Little Hotties Warmers to free-flowing air may cause pouch to become very hot (up to 165°F), which could result in serious burns. Only use Little Hotties as directed.

2. Little Hotties Warmers should not be used under the following conditions:

o Do not apply directly to the skin

o Do not use in shoes during vigorous activies such as running

o Do not use in shoes that have air ventilation holes

o Do not use in oxygen-rich environments

3. Supervision is needed for use with the elderly, infants, children, people with sensitive skin, and for people that can't feel heat.

4. People with diabetes, frostbite, scars, open wounds, or circulatory problems should consult a physician before using the warmers.

5. Remove warmers immediately if they become uncomfortable or too hot.

6. Do not open pouch. Do not allow the contents to come in contact with eyes or mouth. If contact occurs, wash thoroughly with clean water. Contents contain Iron Powder, which can be harmful if swallowed. If contents are swallowed, immediately call a poison control center. Keep out of reach of children & animals.

7. Do not use in oxygen-enriched environments.”

Taken Directly from the Little Hotties Website.

2) An second example of an everyday application for an endothermic reaction is the cold pack, when we are injured or want to keep out lunches cool on long journeys we use cold packs. These absorb heat to keep our food or injured part of our body cool.

3) Another example of exothermic everyday life application is when you put water in the freezer to make ice-cubes. The heat is released and the liquid H20 water turns into solid H2O. The endothermic reaction for H2O is when the ice cube melts, the molecules move more rapidly as it absorbs the heat the H2O changes from a solid to a liquid, and if the heat continues the liquid H2O will change for a solid to a gas.

Photographs: Include a photograph of you or students performing the experiment/demonstration, and a close-up, easy to interpret photograph of the activity --these can be included later.

Videos: Include links to videos posted on the web that relate to your activity. These can be videos you have made or ones others have made.

Cool link about hydrogen and brief simple history and properties. It includes a couple of videos with hydrogen reactions http://www.chemicool.com/elements/hydrogen.html

Song is kind of intense but great video. http://www.youtube.com/watch?v=t2zSWhf4VUg

This video is great because it references the dangers of this particular experiment. It also gives a detailed process of this experiment. Safety is important.

http://www.youtube.com/watch?v=cILG0LjGGMs&feature=related

Sad video about the tragic story of the Hindenburg Explosion where the depth of the dangers of hydrogen were experienced.

http://www.youtube.com/watch?v=F54rqDh2mWA

Link with general information about Carbon Dioxide

http://www.lenntech.com/carbon-dioxide.htm

Carbon Dioxide Balloon Experiment

http://www.youtube.com/watch?v=JmzBf3XGsOE

Educational Link

NEWTON AND ASK A SCIENTIST: Educational Programs

http://www.newton.dep.anl.gov/askasci/chem00/chem00971.htm

References