Plan Investigations Mixing Substances Practice Test

Students want to find out if mixing baking soda and vinegar makes something new. Their plan says: Purpose—watch for bubbles (gas) and temperature change. Materials—baking soda, vinegar, 2 clear cups, 1 tsp spoon, thermometer, tray, paper towels. Safety—Wear goggles, no tasting, wash hands after. Procedure: 1) Measure 2 tbsp vinegar into a cup and record its temperature. 2) Add 1 tsp baking soda and stir. 3) Record bubbles and temperature for 1 minute. What observation would provide the best evidence that a new substance formed?

Students want to find out if mixing baking soda and vinegar creates a new substance. Amir’s plan says: Purpose—see what happens when 1 tbsp baking soda is mixed with 30 mL vinegar in a clear cup. Safety—wear goggles, no tasting, and work on a tray. Procedure—(1) Observe each substance before mixing. (2) Mix and watch for bubbles and temperature change. (3) Record observations in a data table and clean up. Which observation would provide the best evidence that a new substance formed?