Household Substances and Chemical Change

Household Substances and Chemical Change

Household Substances and Chemical Change

Many common substances used in the home are taken for granted. Only rarely do you stop to investigate them or even read the label on their packages. For example, you might have noticed baking soda and baking powder in the kitchen cabinet. Both of these products are used to cause cakes, cookies, and other baked products to rise during the baking process. Are these products the same? Do they give the same results?

In this investigation, you will perform experiments using these common products.

Purpose

Identify the evidence of chemical change.

Identify the difference between two substances, based on evidence from your observations.

Classify some substances as pure substances or mixtures, based on your data.

MATERIALS

  • 4 13- x 100-mm test tubes
  • 1 250-mL beaker
  • Test tube rack
  • Hot plate
  • Scoops or spatulas
  • Baking soda
  • Baking powder
  • Vinegar
  • Deionized water

PROCEDURE

  1. Put on the lab apron and safety goggles.
  2. Fill a beaker about one-third full of water and heat it until it comes to a boil.
  3. Label two test tubes A-1and A-2.
  4. Put baking soda into each of the 2 test tubes to a height of about 1 cm from the bottom of the test tube. (a pinky finger’s width).
  5. Label two other test tubes B-1 and B-2.
  6. Put baking powder into each of these 2 test tubesto a height of about 1 cm from the bottom of the test tube.
  7. To test tubes A-1 and B-1, add deionized water so the test tubes are about half full. Stir with separate glass rods. Record all observations in Table 1. Particularly watch for any release of gas (fizzing).
  8. To test tubes A-2 and B-2, add vinegar slowlyso the test tubes are about half full. Stir with separate glass rods. Record all observations in Table 1. Look for any gas fizzing given off.
  9. Heat test tubes A-1 and B-1 in the beaker with the boiling water. Does any additional fizzing occur?Record the observations in the Table 1.
  10. Heat test tubes A-2 and B-2 in the beaker with the boiling water. Make observations as before. Again, record observations in Table 1.

DATA PRESENTATION

TABLE 1. Data Table

A – baking soda / B – baking powder
Water without heat
With heat
Vinegar without heat
With heat

DATA ANALYSIS

  1. Which conditions were best for the fizzing of baking soda? The fizzing baking powder?
  2. List the ingredients labeled on the packages of baking soda and baking powder.

CONCLUSIONS

  1. Which test gave evidence of a chemical change?
  2. Can it be determined if baking soda and baking powder are mixtures or pure substances? Why or why not?
  3. Write a hypothesis based on the data to explain how one could differentiate between baking soda and baking powder if given an unknown sample.
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