Phase Changes in Everyday Life (Part 2)

What You'll Learn

The law of definite proportions states that a compound always contains the same elements in the same ratio by mass. Water is always 11.2% hydrogen and 88.8% oxygen.

Key Words

product
conservation of mass
solubility

Materials Needed

food coloring
plastic bottles
balloons
measuring cups

Safety First

Clean up spills immediately to prevent slipping.
Use materials only as directed in the experiment.

Steps

Step 1 — Read

Read and learn: The law of definite proportions states that a compound always contains the same elements in the same ratio by mass. Water is always 11.2% hydrogen and 88.8% oxygen.

Step 2 — Do

Build your model using the materials provided.

Step 3 — Observe

Compare the before and after states.

Step 4 — Record

Write your conclusion: did the results match your hypothesis?

Check Your Understanding

Question 1

1 of 3

Which is a sign of a chemical change?