Precipitate+from+Baking+Soda+and+Calcium+Chloride

http://www.middleschoolchemistry.com/lessonplans/chapter6/lesson3

Materials for Each Group
> ===Question to Investigate=== > How do you know when a precipitate is formed in a chemical reaction? > > ===Materials for Each Group=== > Note : If you would like students to practice using a balance to weigh grams, have them weigh two grams each of baking soda and calcium chloride. > > ===Procedure=== >> > > ===Expected Results=== > Bubbling and a white precipitate appear. > ===Ask students:=== > What did you observe when you mixed the baking soda solution and the calcium chloride solution?The solutions bubbled and little white particles of solid formed.Did you observe a precipitate?Yes. The white particles appeared after the two solutions were combined.Do you think this was a chemical reaction? Yes. Why?The two substances that were combined were liquids and the substances that were produced were a solid and a gas. These products seem to be different from the reactants.
 * Baking soda
 * Calcium chloride
 * Water
 * Graduated cylinder
 * Measuring spoon (½ teaspoon) or balance
 * 2 clear plastic cups
 * Masking tape
 * Pen
 * 1) ==Have students combine two liquids to observe another precipitate.==
 * Baking soda
 * Calcium chloride
 * Water
 * Graduated cylinder
 * Measuring spoon (½ teaspoon) or balance
 * 2 clear plastic cups
 * Masking tape
 * Pen
 * 1) Use masking tape and a pen to label 2 plastic cups baking soda solution and calcium chloride solution.
 * 2) Use a graduated cylinder to add 20 mL of water to each cup.
 * 3) Add 2 g (about ½ teaspoon) of calcium chloride to the water in its labeled cup. Swirl until as much of the calcium chloride dissolves as possible.
 * 4) Add 2 g (about ½ teaspoon) of baking soda to the water in its labeled cup. Swirl until as much of the baking soda dissolves as possible. There may be some undissolved baking soda remaining in the bottom of the cup.
 * 5) Carefully pour the baking soda solution into the calcium chloride solution. Try not to pour in any undissolved baking soda. Observe.
 * 1) ===Discuss student observations.===