Visualizing a Graph: Concentration vs Time
Purpose: To examine the relationship between the concentration of a reactant and the amount of gaseous product generated.

Time Required: One 50 minute class period

Prior Knowledge: Reaction rates

Group Size: 6 students

Materials Needed:

• six 100 mL graduated cylinders
• Vinegar
• Baking soda
• Pipet
• Dish soap
• Set of measuring spoons
• Syringe
• Stop watch
Procedure:
1. You will set up a series of six graduated cylinders that contain a constant concentration and volume of vinegar.

1. Using a syringe, measure out 20.0 mL of vinegar and put into each of the 6 100.0 mL graduated cylinder.

2. Add one drop of dish soap to each graduated cylinder.

2. Now you need to measure out 6 piles ,of increasing mass, of baking powder that will be mixed with the vinegar.

1. Measure out 1/4 teaspoon of baking soda onto a small piece of paper.

2. Measure out 1/2 teaspoon of baking soda onto a small piece of paper

3. Measure out .75 teaspoon of baking soda onto a small piece of paper

4. Measure out 1.00 teaspoon of baking soda onto a small piece of paper

5. Measure out 1.25 teaspoon of baking soda onto a small piece of paper

6. Measure out 1.50 teaspoon of baking soda onto a small piece of paper

3. Now it’s time to mix the reagents together!!! You are looking to measure the time that it takes for the top of the soap column to rise up and reach the 100.0 mL mark on the graduated cylinder.

1. Mix 1/4 teaspoon of baking soda with the 20.0 mL of vinegar in the first graduated cylinder. One lab partner can mix the reagents while another lab partner times it. Be sure to start the stop watch as the baking soda is dumped into the vinegar, and stop the timer as the top of the soap column passes the 100.0 mL mark.

2. Repeat with each of the graduated cylinders, recording the time it takes the soap column to pass the 100.0 mL mark.

Data Table:

 Baking soda + Vinegar sodium acetate + water + Carbon dioxide gas NaHCO3 + HC2H3O2 NaC2H3O2 + H2O + CO2

 time (in seconds) graduated cylinder #120.0 mL vinegar + 1/4 teaspoon graduated cylinder #220.0 mL vinegar + 1/2 teaspoon graduated cylinder #320.0 mL vinegar + 0.75 teaspoon graduated cylinder #420.0 mL vinegar + 1.0 teaspoon graduated cylinder #520.0 mL vinegar + 1.25 teaspoon graduated cylinder #620.0 mL vinegar + 1.50 teaspoon

Calculations:
1. Make of graph of your experimental data . Use baking soda measure as the independent variable and the time to reach 100.0 mL as the dependent variable.

2. Construct a line of best fit and calculate the slope of the line.

3. Write the equation for the line.

G Waller

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