Effect of Carbon Dioxide on the Environment

1. Effect of Carbon Dioxide on the Environment Vanderbilt Student Volunteers for Science Training Presentation Spring 2019

2. Important • Please use this resource to reinforce your understanding of the lesson! Make sure you have read and understand the entire lesson prior to picking up the kit! • We recommend that you work through the kit with your team prior to going into the classroom. • This presentation does not contain the entire lesson—only selected experiments that may be difficult to visualize and/or understand.

3. Before you begin… • Give each pair an instruction sheet and handout sheet. Give each student an observation sheet. You will still need to guide them through the procedures, and making sure they are completing the observation sheet. • SAFETY NOTE: Students should not hold pieces of dry ice. The temperature of dry ice is -78° C, and students could get frostbite burns if their skin is in contact with dry ice for more than a few seconds. • Volunteers should use tongs to put dry ice into cups etc.

4. I. Introduction • Please refer to manual for detailed explanations and descriptions. • Discuss facts about Carbon dioxide Make sure you mention that CO2 is a greenhouse gas. B. Discuss of cold temperature of dry ice, using the thermometer diagram. C. Discuss the states of matter – solids, liquids and gases. • Note: Write the different states on the board. Ask the students to identify the processes involved in each change of state, and add to diagram. • There are 5 processes involved in changes of state (freezing, melting, vaporization, condensation and sublimation. Solid (melts)Liquid (vaporizes) Gas Gas (condenses) Liquid (freezes) Solid Solid (sublimes)Gas Gas (deposits)Solid

5. II. Comparing Dry Ice to Water Ice • Give a plate, bags, ice and dry ice to PAIRS.Remind students that they should not touch the dry ice. • VSVS members put a piece of dry ice into a ziploc bag and regular (water) ice into the other bag and close the ziploc fastener. • Ask the students to describe the appearance of the two types of ice and to observe both pieces of ice in the for a few minutes. • Have students describe what happens and record their observations on the observation chart. The dry ice ziploc bag will inflate because of the CO2 gas being given off by the solid. • What changes in states occurred? See manual

6. II. Comparing Dry Ice to Water Ice • Tell students to open the ziploc bags and carefully empty the pieces of dry ice and ice onto the plate. • Tell students to leave the two pieces of ice on the plate, do not move them, but observe them periodically to see what happens over time. • Compare the dry ice with the H2O ice and record observations . • Water ice leaves a puddle, dry ice sublimes to a gas. • “Smoke” comes off dry ice (water vapor in the air condenses around dry ice).

7. Explain what a Greenhouse Gas is • Point to the student handout that has the diagram showing the greenhouse effect • Tell students to look at the handout that has the diagram showing the greenhouse effect and the graph showing the increase in carbon dioxide since the Industrial Age

8. III. Discussion on the Effect of CO2 in Oceans • Write on the board: carbon dioxide sink, acidification • Ask the students what they know about the effect of carbon dioxide on the atmosphere? See manual. • Ask the students what they know about the effect of carbon dioxide on the oceans? See manual. • Write the following equation on the board: CO2+ H2O → H2CO3 Carbon dioxide water carbonic acid • Water in the oceans can remove CO2 directly from the air. • Oceans are called sinks for CO2. • Ask students if they can think of consequences of dissolving increasing amounts of carbon dioxide in ocean waters? (Ocean becomes more acidic). • Acidification could adversely affect marine life. Corals and shells are composed of calcium carbonates which can dissolve in acidic water. • CaCO3(s) + CO2(g) + H2O → Ca(HCO3)2 (aq)

9. III. Observing Changes of Acidity in Ocean Water” Using Dry Ice • Give each pair a clear plastic cup that is about one-third full of “ocean” water. • Show the students the universal indicator and tell them that it is used to measure the acidity of liquids. Have them look at the universal indicator chart. • Tell students: • To add a squirt of universal indicator to the water and observe the color. • Volunteers will place a piece of dry ice into the water. Start observing and record the color changes as soon as the dry ice is added to the cup. • To record everything they observe. • Ask the students to share something they observed. • Draw a picture of the cup (shown below) on the board and record the different observations from the students. • Have the students identify the changes in the states.

10. III. Other observations that can be made. Observations (see manual for explanations) • Dry ice gives off bubbles when it is added to water. • A white fog appears over the water in the top of the glass. • The white fog stays in the top of the glass and any white fog that leaves the glass goes down along the side of the glass rather than up into the air. • Fog that goes down along the glass disappears near the bottom of the glass. • Universal Indicator turns red.

11. IV. Effects of CO2 on Land • Ask students if they know of any examples of CO2 affecting land. • Tell students some CO2 dissolves naturally in rain water • Slightly acidic • This affects exposed rocks • Rain trickles through soils • IMPORTANT: water gets most of its CO2 from soils where CO2 partial pressure is 10-100 times that of the atmosphere. This is important for cave systems. • Water is now more acidic and can dissolve calcite, the mineral in limestone

12. IV. Experiment – Tums • Pass out cups containing a Tums tablet. • VSVSers add dilute HCl to the cup so it is about 1/3 full. • Tell students to observe the reaction. The Tums tablet fizzes and disintegrates. • This models the effect of carbonic acid on seashells etc, and the dissolving of calcium carbonate (limestone rock) to form caves.

13. IV. Effects of CO2 on Land - Cave Formation • Reference the cave diagram while explaining: • Rainwater falls, dissolves CO2 in soils • Water percolates through limestone • Reacts with calcite (CaCO3) to dissolve it. • Leaves behind small cavities which grow over time • Water moves elsewhere in the system • CO2 slowly exolves (leaves solution) converting Ca(HCO3)2 → CaCO3 which is left as a solid • Cave formations such as stalactites/stalagmites

14. How do caves form? (flow chart)

16. V. Review • Review the changes of state and ask the students to give examples from today’s experiments. • What does sublime mean? A solid goes directly to a gas without becoming a liquid. • What is dry ice? Solid carbon dioxide. • How cold is dry ice? -78°C. Refer to the thermometer diagram. • What happens when dry ice is dropped into water? Bubble of carbon dioxide are given off, a cloud forms above the water, the cloud stays in the container instead of floating in the air, if any of the cloud falls out of the container it floats down and disappears.