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Properties of Compounds

Investigation 1 – Lab

Back to Investigation 1

BE PREPARED

Supplies and Equipment:

Class Materials:

6 400 ml beakers
1 100 ml beaker
200 ml white vinegar (Acetic acid)
200 ml rubbing alcohol (Isopropyl alcohol)
200 ml hydrogen peroxide
200 g sugar (Sucrose)
262 g salt (Sodium chloride)
244 g baking soda (Sodium bicarbonate)
38 g cream of tartar (Potassium bitartrate)
3 lab scoops
12 plastic funnels
12 100 ml graduated cylinders
1 roll of masking tape
1 marker
1 Periodic Table poster

Group Materials:

6 100 ml beakers
1 triple beam balance
7 weigh dishes
1 20 cm piece of masking tape
paper towels
2 Periodic Table charts

Individual Materials:

1 Student Data Record

Teacher Preparation:

1. Fill one (1) 400 ml beaker with 200 ml white vinegar and label “vinegar.”

2. Fill one (1) 400 ml beaker with 200 ml rubbing alcohol and label “rubbing alcohol.”

3. Fill one (1) 400 ml beaker with 200 ml hydrogen peroxide and label “hydrogen peroxide.”

4. Fill one (1) 400 ml beaker up to the 200 ml mark with sugar and label “sugar.”

5. Fill one (1) 400 ml beaker up to the 200 ml mark with salt and label “salt.”

6. Fill one (1) 400 ml beaker up to the 200 ml mark with baking soda and label “baking soda.”

7. Fill one (1) 100 ml beaker up to the 40 ml mark with cream of tartar and label “cream of tartar.”

8. Place one (1) lab scoop in the sugar, salt, and baking soda beakers

9. Create six (6) distribution stations.

a. Place each 400 ml beaker that contains one of the compounds at six (6) different locations around the room.

b. Place two (2) 100 ml graduated cylinders and two (2) plastic funnels at each station.

10. Place the 100 ml beaker of cream of tartar at a central location in the lab. Student groups will be instructed to take turns observing the cream of tartar at their lab tables. Because cream of tartar is an expensive replenishable lab item, only one sample of the compound will be used in the lab.

Note: Creating distribution stations is suggested to instructors who are concerned about time or classroom management. By using distribution stations, each student in the group will be responsible for retrieving one or two compounds, instead of one student from the group retrieving all seven compounds. Instructors may also choose to place all seven (7) compounds at a central distribution center.

11. Display the Periodic Table of the Elements poster in the lab.

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

13. Divide the class into five cooperative groups.

Instruction:

1. Direct each student group to obtain the following necessary materials from the distribution point: six (6) 100 ml beakers, one (1) triple beam balance, seven (7) weigh dishes, one (1) 20 cm piece of masking tape, two (2) periodic charts, and several paper towels.

GET FOCUSED

Investigation One introduces students to the properties of compounds by giving them the opportunity to work with six different compounds and compare their properties.

INVESTIGATE

1. In this Investigation, students will examine the qualitative and quantitative physical properties of seven compounds:

baking soda (sodium bicarbonate),
cream of tartar (potassium bitartrate),
salt (sodium chloride),
sugar (table sugar: sucrose),
hydrogen peroxide,
rubbing alcohol (isopropyl alcohol),
vinegar (acetic acid).

Baking soda, cream of tartar, salt, sugar, and vinegar are all common kitchen items that are used for cooking and baking. Hydrogen peroxide and rubbing alcohol are antiseptics that are commonly found in the home.

During Trial 1, students will observe two qualitative properties, state of matter and color. During Trial 2, students will examine two quantitative properties: volume and mass. As students perform the Trials, they should be encouraged to realize that qualitative properties are observed, not measured, while quantitative properties are measured using scientific tools.

Students should also discern that although compounds can share similar properties, they each have a unique set of properties that define them. As students perform the Trials, they will focus on the following questions:

- - Does a single qualitative or quantitative property distinguish one compound from another?
  - Do compounds that have similar elements have similar properties?
  - Do compounds that have different elements have different properties?
  - Can compounds that have different elements have similar properties?

Trial 1

2. This Trial has been designed to give students an opportunity to examine some of the qualitative physical properties of seven compounds: baking soda, cream of tartar, salt, sugar, hydrogen peroxide, rubbing alcohol, and vinegar.

Students will collect a 40 ml sample of each of the six compounds from distribution stations around the room. Student groups will take turns examining a 40 ml sample of cream of tartar that is found at a central location in the lab. They will then observe two qualitative properties of the compounds: state of matter (solid, liquid, or gas) and color. Students should come to realize that these two properties alone do not distinguish one single compound from the others. As students complete this Trial, they will consider the following questions:

- - What are some of the qualitative properties of compounds?
  - Do these properties alone distinguish one compound from another?
  - Do compounds that have different elements have different properties?
  - Do compounds that have similar elements have similar properties?

Trial 2

3. In this Trial, students will determine the volume and mass of each of the seven compounds. When obtaining their samples of compounds from the distribution stations, students were asked to use a graduated cylinder to measure 40 ml of the sample. A graduated cylinder was used because it is more accurate than a beaker for measuring volume.

To determine the mass of each 40 ml sample, students will be using a previously used tool from the Procedural Toolbox, the triple beam balance. By performing this Trial, students should discern that the mass of each 40 ml sample is different, and therefore, is a unique property for each compound.

Students may also begin to understand that a compound is distinguished from other compounds by a set of unique properties. Students should also realize that volume and mass are quantitative properties because they can be measured using scientific tools. As students complete this Trial, they should consider the following questions:

- - Are volume and mass qualitative or quantitative properties of compounds?
  - How can volume and mass be measured?
  - Does volume and mass alone distinguish one compound from another?
  - Do compounds that have different elements have different properties?
  - Do compounds that have similar elements have similar properties?

Encourage students to summarize their observations from the lab by answering Problem 3 in their Student Data Record. The Table from Problem 3 is shown above. The Table lists the elements (from The Periodic Table of the Elements) in each of the compounds analyzed in this lab. A Periodic Table of the Elements is also included below for referrence.