How do science concepts apply to your world? Here are some questions you'll be able to answer after you read this chapter.

• What happens to a piece of charcoal as it burns?
• How do air bags inflate?
• Why does a propane stove need a spark in order for the propane to ignite?
• How does a refrigerator keep food fresh?
• What changes take place inside a closed container of water?
• How do firefighters put out wildfires?

How Is Mass Conserved in a Chemical Change?

Procedure

1. Pour 100 mL of water into a resealable plastic bag. Flatten the bag to remove all of the air and then seal the bag. Measure and record the mass of the bag and the water.
2. Measure and record the mass of a square piece of paper with sides of 10 cm. Place an antacid tablet on the paper. Measure and record the mass of the tablet and the paper together. To find the mass of just the tablet, subtract the mass of the paper from the combined masses of the tablet and the paper.
3. Record the combined masses of the bag, the water, and the antacid tablet.
4. Slightly open one side of the bag and drop the tablet into the water. Quickly reseal the bag. After the bubbling has stopped, measure and record the mass of the bag and its contents.

Think About It

1. Applying Concepts   How do you know whether a chemical change took place?
2. Inferring   What happened to the mass of the plastic bag and its contents after the bubbling stopped? What might this information tell you about a chemical change?