Energy in Chemical Reactions Lab
Introduction:
Every chemical reaction involves a change of energy. Some reactions release energy and others absorb energy. A reaction that releases energy in the form of heat (and therefore the temperature increases) is called an exothermic reaction. A reaction that absorbs energy (and therefore the temperature decreases) is called an endothermic reaction.
Procedure:
1. Use the measuring cup to measure 60 ml of water. Put water into the Styrofoam cup. Insert thermometer into the water and record the temperature in °C.
2. Place the thermometer through the hole that is at the center of the lid to the cup.
3. Use a small plastic spoon and scoop a spoonful of calcium chloride (CaCl2). Pour the calcium chloride into the water. Immediately use the lid with the thermometer to cover the cup. Make sure the bottom of the thermometer is touching the bottom of the cup. If the temperature rises, record the highest temperature reached. If the temperature lowers, record the lowest temperature reached.
4. Calculate the temperature change. Rinse out and dry the Styrofoam cup.
5. Repeat step one—use vinegar (acetic acid) instead of water.
6. Repeat step 2.
7. Use a small plastic spoon and scoop a spoonful of baking soda. Pour the baking soda into the Styrofoam cup. Immediately use the lid with the thermometer to cover the cup. If the temperature rises, record the highest temperature. If the temperature lowers, record the lowest temperature reached. Calculate the temperature change. Rinse out and dry the Styrofoam cup.
8. Repeat steps 1 and 2 using water.
9. Use a small plastic spoon and scoop a spoonful of sugar. Pour the sugar into the Styrofoam cup. Immediately use the lid with the thermometer to cover the cup. If the temperature rises, record the highest temperature. If the temperature lowers, record the lowest temperature reached. Calculate the temperature change. Rinse out and dry all equipment. Make sure lids are on all containers and are secure.
Data Table:
Reaction / Temperature of liquid only (°C) / Highest or lowest temperature reached (°C) / Temperature change (+ or - °C)Water and calcium chloride (CaCl2)
Vinegar and baking soda
Water and sugar
Questions
1. Make a bar graph showing the temperature change for each reaction. Make sure the x and y axes are labeled, the units labeled, and the bars labeled.
2. Did a chemical reaction happen for each mixture? Explain.
3. Which chemical reaction was exothermic? Discuss the data that led you to your answer.
4. Which chemical reaction was endothermic? Describe the data that led you to your answer.