Identifying Acids and Bases

Designed by: Margaret Knight School:Gibbes Middle School

Grade Level:  6     Subject(s):  Science

Core Curriculum Objective(s):  Compare and contrast chemical and physical changes/ The student will investigate, compare, contrast, and understand that matter has physical and chemical properties and can undergo changes. Students will determine the relationship that exists between color change of a substance and its pH level.  (6ME-1)

Overview: Students will use cabbage juice to identify, compare, and contrast acids and bases.

Focus/Essential Question(s): What characteristics differentiate acids from bases?

Time Frame: (1) 50 minute class period

Bibliography:  

VanCleaves, Janice. A+ Projects in Chemistry.  New York: John Wiley and Sons, Inc. 1993. 

Science Interactions. Glencoe/McGraw-Hill: Copyright 1995 Glencoe/McGraw-Hill Westerville, Ohio, pp. 186-197. 

Physical Science. Steck-Vaughn Science Series/ Copyright 1999

Materials: red cabbage juice, lemon juice, sprite, vinegar, water, ammonia, baking soda, lye, dishwashing liquid, alka-seltzer, goggles, rubber gloves, aprons, plastic cups, glass rods, paper towels

Culminating Assessment: Students will create a data table and record data from the experiment. Students will write a report from the data gathered which compares and contrasts the properties of acids and bases. 

Extension: Students will design an experiment to test the strength or weakness of acids and bases using cabbage juice.

Instructional Activities: Students will be divided into groups of four. Review the properties of acids and bases found in chapters 6-1 and 6-2, pp. 186-197, of Science Interactions. Introduce activity using the focus question and list student's responses. Explain the procedures and expected assessment for the investigation. Monitor students throughout the experiment.

Procedures: 

1) Cover a work surface with paper towels. 

2) Put on eye goggles, plastic gloves, and aprons. 

3) Pour 2 mL of each liquid into a plastic cup and label with permanent marker. 

4) Place 1 mL of red cabbage juice into each cup and stir using a clean stirring rod. 

5) Observe each reaction and record data. 

6) Analyze the data. 

7) Write a report which compares and contrasts acids and bases. 

8) Use the rubric to make sure data table and report are complete. 

9) Extension: 

For early finishers: Design an experiment to test the strength or weakness of an acid or base using red cabbage juice.

Rubric for Data Table: