3.6 WATER PROPERTIES How do you make ocean water? Activity Time: 15 minutes Background Materials Seventy percent of the earth is water, and of that, 97% is salt water. Where does that salt come from? Every 1 picture graph of sea water* stream and river that flows into the ocean carries some amount of salt in it. The salt comes from erosion of 1 globe the minerals in those waters. It is said that one fourth of the material that the Mississippi River deposits in the ocean is dissolved minerals. Ocean water contains about 3.5% salts, mostly sodium chloride (table salt), Per Group: potassium, and calcium and magnesium salts. Small plants and animals (plankton) use some of the salts Table salt and the ocean floor removes some of them as well. Most of the table salt remains in the water, however, and Pitcher of water that accounts for the taste. 1 teaspoon 1 metric measuring pitcher 1 plastic spoon per person Large spoon for stirring Directions 2 small rocks for each student Teacher introduces kinds of water and its location by showing globe. Make a list of what students know on board. Students: 1. Measure 3 1/2 teaspoons of salt into a metric pitcher. 2. Add 1000 ml (or 4 1/4 cups) of water. 3. Stir the salt and water. Vocabulary 4. Taste the sea water by using a clean plastic spoon. Mineral: a substance that 5. Rub 2 rocks together and place in saltwater pitcher. occurs naturally in rocks and in the ground that has its own Discussion appearance and chemical composition. • Where does the ocean get its salt? (From rivers) • Where do rives get their minerals like salt? (From rocks) Dissolve: to become absorbed • Can you see the salt in water? (Water is a solvent, so if it is not saturated, the salt disappears.) in liquid. • What is salt? (Soldium chloride, a chemical compound that contains an acid and a base.) Volume: sodium chloride, which Assessment is a chemical compound that contains and acid an a base. Complete Assessment 3.6: How do you make ocean water? (See Rubric 3.6 for scoring.) Extension ALIGNMENT TO NGSS: • Research the chemical compound of salt to find an image of the elements combined. Scientific and Engineering Practices • Make your own salt by filling a tablespoon halfway with vinegar. Spring baking soda over • Asking questions • Developing and using models the vinegar until the bubbling stops. Which ingredient is the acid and which is the base? • Planning and carrying out investigations Related Activities • Constructing explanations • Engaging in argument from How do you lift an iceberg with a string? (4.2) evidence • Obtaining, evaluating, and communicating information Crosscutting Concepts • Cause and effect • Stability and change Disciplinary Core Ideas • K-5: ESS2.A; ESS2.C; PS1.A • 6-8: ESS2.A; ESS2.C; PS1.A.