Materials:
Safety goggles
Graduated cylinders
Small plastic cups
Ice
Antacid tablets
Clay
Baking soda
Vinegar
Milk
Drink mix
Purpose:
Upon completion, the learner will be able to differentiate between physical and chemical changes. Physical changes occur when objects undergo a change that does not change their chemical nature. A physical change involves a change in physical properties. Physical properties can be observed without changing the type of matter. Examples of physical properties include: texture, shape, size, color, odor, volume, mass, weight, pH and density.
Chemical changes are changes substances undergo when they become new or different substances. For example, the fireworks we see on the 4th of July are actually metals such as magnesium and copper that change chemically as they light up the night skies with their fantastic colors. To identify a chemical change look for observable signs such as color change, bubbling and fizzing, light production, smoke, and presence of heat.
At your table, observe and describe the antacid.
Break the tablet into small pieces. Is this a physical or chemical change?
Fill your cup 1/2 full of water. Add the antacid tablet. Observe what happens. Is this a physical or chemical change?
A doctor might tell someone to use an antacid if their stomach produces too much acid. Based on what you observed, how do you think antacids work?
1. Place an ice cube in your small paper cup.
2. Observe and record how the ice looks and feels as your response.
3. Set the cup aside until you have 10 minutes left in class.
Now that a period of time has passed, observe your ice cube. Is this a physical or chemical change?
Remove the clay from its container and describe how it looks, feels and smells.
Break the clay up into many small pieces. Observe and record the change. How is it different? How is it the same?
What kind of change is this?
Add 1 scoop of baking soda to a clean, dry cup. Using a small beaker to measure, add 10 ml vinegar to the baking soda. Observe and record the change.
What kind of change is this?
Using a graduated cylinder, measure 25 ml of milk and add it to your beaker.
Now add 25 ml of vinegar to the beaker.
Observe and record any changes.
What kind of change is this?
Add 1 scoop drink mix to your beaker.
Now add 50 ml of water to your beaker.
Gently mix by swirling.
Observe and record the change.
What kind of change is this?
How would you classify sample A?
How would you classify sample B?
How would you classify sample C?
How would you classify sample D?