Name Date Class
QUICK LAB: Strengths of Covalent bonds
Laboratory RecordsheetUse with Section 8.2
PURPOSE
To compare and contrast the stretching of rubber bands and the dissociationenergy of covalent bonds.
MATERIALS- 170-g (6-oz) can of food
- 2 454-g (16-oz) cans of food
- 3 No. 25 rubber bands
- metric ruler
- coat hanger
- plastic grocery bag
- paper clip
- graph paper
- pencil
- motion detector (optional)
PROCEDURE
1. Bend the coat hanger to fit over the top of a door. The hook should hang downon one side of the door. Measure the length of the rubber bands (in cm). Hanga rubber band on the hook created by the coat hanger.
2. Place the 170-g can in the plastic grocery bag. Use a paper clip to fasten thebag to the end of the rubber band. Lower the bag gently until it is suspendedfrom the end of the rubber band. Measure and record the length of thestretched rubber band. Using different food cans, repeat this process threetimes with the following masses: 454g, 624g, and 908g.
3. Repeat Step 2, first using two rubber bands to connect the hanger and thepaper clip, and then using three.
4.Graph the length difference: (stretched rubber band) – (unstretched rubberband) on the y-axis versus mass (kg) on the x-axis for one, two, and threerubber bands. Draw the straight line that you estimate best fits the points foreach set of data. (Your graph should have three separate lines.) The x-axis andy-axis intercepts of the lines should pass through zero, and the lines shouldextend past 1 kg on the x-axis. Determine the slope of each line in cm/kg.
Chapter 8 Covalent Bonding207
Name Date Class
ANALYSES AND CONCLUSIONS
1. Assuming the rubber bands are models for covalent bonds, what can youconclude about the relative strengths of single, double, and triple bonds?
2. How does the behavior of the rubber bands differ from that of covalent bonds?
208Core Teaching Resources