Skip to main content

Physical vs. Chemical Changes

Main Image
Chemistry Volunteer Activities
Main Image
Chemistry Volunteer Activities
Activity Language
Grade
Time Needed for Activity

Students use kitchen materials to look at changes and determine if they are chemical or physical changes.

This activity set is from the Grade 5 Ontario curriculum.

What You Need

Materials if dropping off at a school:

Students can work individually or in pairs for this activity.

  • 1 baggie with ~2 teaspoons of baking soda (Powder A)
  • 1 baggie with ~2 teaspoons of baking powder (Powder B)
  • 1 Baggie with ~2 teaspoons of corn starch (Powder C)
  • 1 Alka Seltzer tablet broken into 2 ("Tablet")
  • Recording sheet and instructions
  • 8 labelled cups per individual/pair of students. These cups have about 1/2 inch from the bottom and are labeled. 

For the teacher:

  • 1 full container of vinegar (for the teacher to distribute) - Each student/pair requires 1/2 cup
  • 1 film canister with a tight fitting lid - the ones where the lid fits inside the canister (for the teacher)
  • 2 tsp baking powder in a separate bag for the teacher
  • A spoon
  • Safety goggles
  • Large pie plate for catching the rocket liquid.

Materials if NOT dropping off at a school:

  • 1 baggie with ~2 teaspoons of baking soda (Powder A)*
  • 1 baggie with ~2 teaspoons of baking powder (Powder B)*
  • 1 Baggie with ~2 teaspoons of corn starch (Powder C)*
  • Optional: an Alka Seltzer tablet or some powder antacid like Eno
  • 1 spoon
  • Recording sheet and instructions
  • Transparent cups or bowls (8 if possible)
  • Approximately ~1/2 cup of vinegar
  • ~1/2 cup of water
  • Video of elephants toothpaste

*If possible have them ask as parent or sibling to place these powders into small bowls or containers and label them A,B and C but do not tell them which is which.

Guide:

Safety Notes

As a Let’s Talk Science volunteer, safety must be foremost in our minds during all activities. As STEM role models, volunteers must always also model safe science practices.

Always keep in mind the following precautions:

  • Emphasize and demonstrate appropriate safety procedures throughout the presentation.
  • Be professional but have fun.
  • Keep workspaces clean to avoid tripping hazards.
  • Allergens should have been checked before reserving the kit (e.g. allergies to latex).
  • Activity Specific Safety: Remind students not to eat or drink anything in the experiments or to eat and drink while doing experiments. Also they are not to touch the liquids and then touch their eyes – this would be for the vinegar as it will sting their eyes. Alka Seltzer (the tablet) contains aspirin which can be harmful to children under 12.

What To Do

Have the educator distribute the materials, instructions and the recording sheet.

Experiment Procedure:

  1. Start with the set of cups labelled "AA", "AB", "AC" and "A-Tablet".
  2. Add "Liquid A" up to the line on each cup. 
  3. Add 1 teaspoon (doesn't have to be exact) of "Powder A" to cup "AA".
  4. Observe what happens and record it in the correct column in the table. Based on your observations, predict whether there has been a chemical or physical change (or both) and why you think this. 
  5. Add 1 teaspoon of "Powder B" to cup "AB".
  6. Observe what happens and record it in the correct column in the table. Based on your observations, predict whether there has been a chemical or physical change (or both) and why you think this. 
  7. Add 1 teaspoon to "Powder C" to cup "AC".
  8. Observe what happens and record it in the correct column in the table. Based on your observations, predict whether there has been a chemical or physical change (or both) and why you think this. 
  9. Put 1/2 the "Tablet" into the cup labelled "A-Tablet".
  10. Observe what happens and record it in the correct column in the table. Based on your observations, predict whether there has been a chemical or physical change (or both) and why you think this. 
  11. Repeat this procedure with Liquid B and the cups that start with B.

Discovery