Pure Substances vs. Mixtures

1. Pure Substances vs. Mixtures Salt and Water

2. Pure Substance vs. Mixture • Salt (sodium chloride) is a pure substance. • Distilled water (HOH) is a pure substance. • Salt in water is a special mixture called a solution. • What properties of water and salt allow them to mix so well? Check out the animation at Iowa State University. • Animation of Salt in Water

3. Challenge • Using a mesh screen, funnel and stand, coffee filter, two cups and water, separate a mixture of gravel, sand, and salt based on the properties of each substance. • Write down your procedure.

4. Solution to Challenge • Place the coffee filter in the funnel. • Place the mesh screen over the top of the funnel. • Place a cup under the funnel. • Pour the sand, gravel, salt mixture onto the mesh screen. • Go to next slide.

5. Solution to Challenge • The size of the gravel keeps it from going through the mesh screen. Pour the gravel into a small plastic bag. • Pour water over the sand and salt that are in the coffee filter. • Salt will dissolve in water and pass through the coffee filter. Sand will remain in the coffee filter. • Go to next slide.

6. Solution to Challenge • Set the sand aside to dry. • Test the water for conductivity. If it conducts electricity, then salt passed through the filter. • Boil off the water and retrieve the salt crystals. • You now have gravel, sand, and salt separated from each other. • Go to next slide.

7. Pure Substance? • Is sand a pure substance? • Is gravel a pure substance? • Is salt a pure substance?

8. Pure Substance or Mixture? • Air • Beach sand • Italian salad dressing • Ocean water • Salt • Sugar • Distilled water • Soda • Cupcake batter

9. Air Beach sand Italian salad dressing Ocean water Salt Sugar Distilled water Soda Cupcake batter Mixture Mixture Mixture Mixture Pure substance Pure substance Pure substance Mixture mixture Answers