Name ______Per. ______Date ______
Energy in Matter – Chemical Reactions (25 points)
Introduction
All matter contains energy. However, not all matter contains the same amount of energy. The particular organization of atoms in a substance determines its precise amount of energy. In this activity, you will investigate some of the links among matter, energy, and organization and attempt to describe the close relationship among them.
Materials
Safety goggles Sodium biocarbonate
Lab apron 30% Calcium chloride solution
10 mL graduated cylinder 50 mL flask
Test tube rack Test tube
1M HCl solution Ammonium nitrate
2 cm piece of magnesium room temp. water
Precautions: Avoid skin/eye contact when using chemicals. Wear goggles and aprons.
Pre-lab
1. Define matter. Give three examples of matter.
2. Define energy. Give three examples of energy.
3. How are matter and energy related? Give one or two examples.
Experiment 1
1. Use a graduated cylinder to measure 5 mL of 1M HCl. Pour this into a test tube that is firmly seated in a test tube rack. Do not remove the test tube from the rack.
2. Feel the outside of the test tube to note the relative temperature. Describe below.
3. Place 2 cm of magnesium ribbon into the acid in the test tube, and observe what happens as the solid dissolves. Record your observations below.
Observations:
4. Feel the test tube and record your observations below:
Observations:
5. Name the type of reaction you have observed. ______
6. Pour HCl and magnesium strip into disposal container and rinse the test tube.
Experiment 2
1. Put approximately 40 mL of room-temperature water in a flask.
2. Feel the flask to note the relative temperature. Describe below.
3. Call your teacher over to put about 2 spatulas of dry ammonium nitrate into the water in the flask, and swirl it gently to dissolve the powder.
4. Feel the flask, and record your observations below.
Observations:
5. Name the type of reaction you have observed. ______
6. You may pour the solution into the sink and rinse the flask.
Experiment 3
1. Use a graduated cylinder to measure 3 mL of calcium chloride. Pour this into a test tube that is firmly seated in a test tube rack. Do not remove the test tube from the rack.
2. Feel the outside of the test tube to note the relative temperature. Describe below.
3. Add three spatulas of sodium bicarbonate to the calcium chloride in the test tube. Mix with stirring rod. Record your observations below.
Observations:
4. Feel the test tube and record your observations below.
Observations:
5. Name the type of reaction you have observed. ______
6. Pour the contents of the test tube into the sink. Rinse the test tube.
Analysis Questions (3 points each)
1. Describe where the energy needed for the endothermic reaction came from. Describe where the energy produced by the exothermic reactions went.
2. What do you thin happened to the organization of the solid ammonium nitrate molecules when they dissolved in water?
3. If an exothermic reaction releases heat, why is it inaccurate to say that an endothermic reaction releases cold?
4. Explain why the energy that is stored in the chemical bonds of a molecule is not destroyed when that molecule is broken down into smaller molecules.