Carbon Dioxide Gas Formation: Time vs Quantity CaCl2(Rana Khan-Megan Whitaker)

Research Question and Hypothesis

How does the quantity of 1 reactant affect the amount of time it takes for Carbon Dioxide gas formation to fill the volume of a ziplock bag?

Hypothesis: The larger the amount of Calcium Chloride added to a constant amount of Sodium Bicarbonate, the faster the reaction rate is and the larger amount of Carbon Dioxide gas production.

Standards

• PS1-2. Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred.

Experimental Design

Students will use variable amounts of Calcium Chloride mixed with a constant amount of Sodium Bicarbonate and the indicator Phenol Red to test how long it takes for the reaction to produce enough Carbon Dioxide gas to fill (and pop) a sandwich sized ziplock baggie.

Independent variable

The independent variable is the amount of Calcium Chloride added to the reaction. This variable is tested by measuring the amount of time it takes to react and produce Carbon Dioxide gas to fill the ziplock bag.

Dependent variables

The amount of time it takes for the Carbon Dioxide gas to fill the ziplock bag. The ziplock bag reaction will be timed from the moment the Phenol Red and water solution are added until the moment the ziplock bag pops.

Series

Study the formation of Carbon Dioxide gas as a function of time with various amount of Calcium Chloride as one of the reactants.

Constants and Controls

The factors that are controlled were the size of the ziplock bag, the ratio of Phenol Red to water, the amount of Phenol Red solution, and amount of Sodium Bicarbonate.

The control is the ziplock bag that contains a 1 to 1 ratio of Calcium Chloride to Sodium Bicarbonate.

Materials

Calcium Chloride

Sodium Bicarbonate

Phenol Red (diluted in water)

Sandwich ziplock bags

2 ring stands with test tube clamps

3 ( 25mL) beakers

Procedures

1. Label each bag, 1 to 1, 1 to 0.5, 1 to 1.5, 1 to 2, 1 to 2.5

2. In each bag, add 20 mL of Sodium Bicarbonate.

3. According to the label on the bag, add 20 mL, 10 mL, 30 mL, 40 mL, and 50 mL of Calcium Chloride into the bags.

4. Clip the control bag (1 to 1) between the test tube clamps attached to the ring stand so that the sides of the bag are sealed, the middle of the bag is open, and the bag is held suspended between the ring stands.

5. In another beaker, pour 20 mL of Phenol Red solution, and add it to the ziplock bag. Seal the bag immediately and start timing.

6. Observe the reaction happening in the bottom of the bag. Keep timing until the bag completely inflates and the zipper seal pops.

7. Repeat the procedure (2-6) for the other four amounts of Calcium Chloride.

8. Record the times in the spreadsheet.

Sample data and graphs

Analysis & Conclusions

The chemical reactions were all fairly quick with the amount of time differing by only 43 seconds between the smallest amount of Calcium Chloride and the largest amount of Calcium Chloride. While the amount of CaCl2 seems to have an impact, I believe that the limiting reagent is actually the Sodium Bicarbonate.

Photos & Movies

References

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