Observation and Experiment
Lab Objective: To make observations about the changes that occur when several substances are mixed and to design controlled experiments to identify the substances responsible for the observed changes.
Materials: We did not use graduated cylinders or beakers.
Pen for labeling
Jars or plastic cups, small, 2
Sealable, zipper-lock plastic bags, quart
Measuring spoons, teaspoon and
half-teaspoon, 1 each
Water, distilled, or deionized
Phenol red, 0.02% aqueous solution 30mL
Sodium Bicarbonate (solid), 3 tsp.
Calcium Chloride (solid), 6 tsp.
Safety Precautions: Calcium chloride is slightly toxic by ingestion. Phenol red is a dye solution and will stain skin and clothing. Avoid contact of all chemicals with skin and eyes. Be careful to mix the chemicals in the amounts called for in the procedure. Adding too much of the solids may cause chemical splattering or splashing. Wear chemical splash goggles, chemical-resistant gloves, and a chemical-resistant apron. Wash your hands with soap and water before leaving the lab.
Procedure Part A: The Overall Reaction (refer to lab handout) Procedure Part B: Controlled Experiments!
1) Mix only the calcium chloride and red phenol, and observe any changes that occur. 2) Mix only the sodium bicarbonate and red phenol, and observe any changes that occur. 3) Mix the water and both substances, and observe any changes that occur. Data: Individual Properties
substance is white and powdery
substance is white and powdery yet ballish
Observations: During the overall reaction, the chemical changes began to occur when the phenol red started mixing with the two substances. The calcium chloride turned yellow, foamy and hot, while the sodium bicarbonate turned cold and pink. By this time in the reaction...
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