Teacher Portal:

Properties of Compounds

Investigation 5 – Lab

Back to Investigation 5

BE PREPARED

Supplies and Equipment:

Class Materials:

40 g salt
75 g baking soda
1 L vinegar
500 ml rubbing alcohol
1.9 L water
400 ml hydrogen peroxide
1 knife
1 lab scoop
15 400 ml beakers
10 100 ml beakers
1 100 ml graduated cylinder
2 weigh dishes
1 triple beam balance
1 large potato
2 15 ml centrifuge tubes
1 roll masking tape
1 marker
paper towels

Group Materials:

3 400 ml beakers
2 100 ml graduated cylinders
2 glass stir rods
1 pair of tongs
1 liter pitcher
3 8 cm pieces of masking tap

Individual Materials:

1 Student Data Record

Teacher Preparation:

1. Fill one centrifuge tube with 15 g of baking soda for each group. To do this, fill one (1) 15 ml centrifuge tube to the 14 ml line with baking soda. Label the falcon tube “baking soda.”

2. Fill one centrifuge tube with 8 g of salt for each group. To do this, fill one (1) 15 ml centrifuge tube to the 7 ml line with salt. Label the centrifuge tube “salt.”

3. For each group, fill two (2) 400 ml beakers with 100 ml vinegar.

4. For each group, fill one (1) 400 ml beaker with 100 ml rubbing alcohol.

5. Slice the potato into small pieces approximately 2 cm × 2 cm. Each group will need two pieces of potato.

6. For each group, prepare one beaker of water. Pour 80 ml of water into one (1) 100 ml beaker.

7. For each group, prepare one beaker of hydrogen peroxide. Pour 80 ml of hydrogen peroxide into one (1) 100 ml beaker.

8. Place materials required by student groups at the distribution point.

9. Divide class into five cooperative groups.

Instruction:

1. Direct each student group to obtain the following necessary materials from the distribution point: three (3) 400 ml beakers, two (2) 100 ml graduated cylinders, two (2) glass stir rods, one (1) pair of tongs, one (1) 15 ml centrifuge tube containing baking soda, one (1) 15 ml centrifuge tube containing salt, two (2) 400 ml beakers containing vinegar, one (1) 400 ml beaker containing rubbing alcohol, one (1) 100 ml beaker containing water, one (1) 100 ml beaker containing hydrogen peroxide, two (2) pieces of potato and three (3) pieces of masking tape, each approximately 8 cm in length. Instruct one student to fill one (1) liter pitcher with 300 ml water.

GET FOCUSED

Investigation Five introduces students to chemical reactions that may occur when compounds are mixed. In LabLearner middle school, and entire CELL is devoted to delving into this topic in much further detail.

INVESTIGATE

1. During this Investigation, students will explore chemical reactivity by combining various compounds. Students will observe the interactions between these compounds and will see that some compounds react with others while some do not. While making these observations, students should focus on the following question:

Do compounds made of the same elements react the same way?

Trial 1

2. During this Trial, students will observe the interaction between vinegar and baking soda solution. Students will observe the compounds to determine whether or not signs of chemical change are exhibited as they are combined.

Students will observe the compounds as they create a solution. Students will observe that bubbles are formed, indicating that a gas is released. The release of gas is another sign that a chemical change may have occurred.
When performing this trial, students will focus on the question:

What is the chemical reactivity between vinegar and baking soda?

Trial 2

3. During Trial 2, students are instructed to combine rubbing alcohol and the baking soda solution. Again, students will look for signs that a chemical change may have occurred.

Students will observe the compounds as they create a solution. When combining the compounds, students will observe no sign that a chemical change may have occurred.

By performing this Trial, students will begin to answer the question:

What is the chemical reactivity between rubbing alcohol and baking soda?

Trial 3

In Trial 3, students combine vinegar and a salt solution. Students will again look for signs that a chemical change has occurred.

Students will observe the compounds as they create a solution. When combining the compounds, students will observe no sign that a chemical change may have occurred.

By conducting this Trial, students will answer the question:

What is the chemical reactivity between vinegar and salt solution?

Trial 4

5. Thus far in this CELL, students have explored a variety of compounds. During this Trial, students will investigate a familiar compound, water, and a new substance, potato. Although this CELL focuses on compounds and their properties, it is important to realize that a potato is not a compound. Rather, it is a mixture of many compounds. Through Trials 4 and 5, students will explore the chemical reactivity between a potato and two compounds: water and hydrogen peroxide.

In Trial 4, students will add a piece of potato to water and look for any indication that a chemical change has occurred. Students will not observe any other sign of a chemical change.

By performing this Trial, students will answer the question:

What is the chemical reactivity between potato and water?

Trial 5

6. During this Trial, students will add a piece of potato to another compound, hydrogen peroxide. Students will add a piece of potato to a beaker of hydrogen peroxide and look for any indication that a chemical change has occurred.

Students will observe the production of bubbles, indicating that a gas has been produced. The production of gas is a sign that a chemical change may have occurred.