| Unit 3: Active Chemistry |
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- For each material you thought was a mixture, write your best guess about what materials make it up.
2. Sometimes the materials that make up a substance are not obvious. Early scientists thought that water was an element. In other words, they thought that there was only one kind of material in water. They had not discovered a way of breaking it down further. Water, however, can be broken down further.
- Carefully observe the characteristic
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| Safety goggles and a lab apron must be worn during this activity. |
properties of water. Record your observations in your log.
3. Put on your safety goggles and apron. Assemble the apparatus for decomposing water as shown in the diagram. Fill two test tubes with water. Submerge them in the water in the beaker and invert them. Make sure you do not allow any air to enter the test tubes. Make sure that the ends of the wires are stripped. Polish
them with steel wool. Insert the ends of the wires into the test tubes. Add about 1 to 2 mL of sodium sulfate solution to the water in the
beaker.
4. Plug in the battery. Let the reaction run until
a test tube is full of gas.
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(Your teacher may decide to have you stop the reaction sooner.)
- Note what happens when the power is turned on. Record your observations in your Active Chemistry log.
- How do the relative amounts of gas formed in the test tubes compare?
5. Disconnect the battery. Place stoppers on the test tubes and remove them from the water.
- What gas do you think is contained in each test tube? (Hint: You’ve probably heard that water is H-2-O, written, H2O.) Record your prediction, and give reasons for your prediction.
- Observe the physical properties of each gas. Record these properties in your log.
6. You are going to use a lighted wooden splint
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| Be certain that the mouth of the test tube is pointed away from everyone. |
to identify the gas in each test tube. First, examine the test tube with the smaller volume of gas. Light a wooden splint. Blow out the flame, but leave the splint glowing. Hold the test tube with its mouth up. Remove the stopper. Quickly bring the glowing splint to the mouth of the test tube.
- Observe what happens to the splint, and record your observations.
- What gas do you think was produced in this test tube?
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| Clean up spills immediately. |
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Activity Page 2 
