Physical and Chemical Changes

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Presented by Kesler Science

Vers. 08/2020 © Kesler Science, LLC

Essential Questions:

Reflect on the Essential Questions before you dive in…

1. If you were quizzed today, what parts of the question would you know the answers to already?

2. Which parts of the questions would you need to learn more about to answer confidently?

1. How does evidence of chemical reactions indicate that new substances with different properties are formed?

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Physical & Chemical Changes

Chemical Reaction

• Occurs when two or more molecules interact and the molecules change into a new substance.

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• Bonds between atoms are broken and created to form new molecules.

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What do you notice about the molecules before and after the chemical reaction (before and after the arrow)?

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Physical & Chemical Changes

Type your answer here

Physical Change

• Changes the form or appearance of a substance

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• Does not change substance into anything new

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• Examples
• Whipping eggs
• Boiling water
• Dissolving sugar
• Dicing vegetables

Name one more example of a physical change.

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Physical & Chemical Changes

Type your answer here

Smooth

Physical Changes

• Changing the state of matter

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• Changing the color

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• Changing the temperature

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• Changing the shape

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• Changing the texture

What are the physical characteristics of the ice cube?

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Physical & Chemical Changes

Smoke or Fire

Does not change substance into anything new

Bubbles or Fizzing

Unexpected Temperature Change

Change in color

Precipitate is formed or new Substance formed

Changes the form or appearance of a substance

Change in the state of matter (ex. Solid to liquid)

Unexpected Color Change or Rusting

Change in shape or texture

Find the evidence for physical changes and place them in the test tubes. (Click on and drag the labels to the test tubes. You can rotate by using the rotate tool when you click on the label.)

PHYSICAL CHANGES

What do you think the remaining cards are evidence of?

Physical Change

Physical Change

Physical Change

Physical Change

Physical Change

Quick Action: INB

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Chemical Change

• When two or more substances join to form new substances with new chemical properties

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• Examples
• Iron rusting
• Gas burning
• Eggs cooking
• Bread rising

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Physical & Chemical Changes

1. What is the main difference between a substance going through a physical change and one going through a chemical reaction?
2. Why is making fruit popsicles a physical change?

Think About It

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Unexpected Color Change

New molecules created in a chemical reaction radiate light differently producing new colors.

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Examples:

• Fireworks
• Leaves changing from green to orange and red in the fall

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Physical & Chemical Changes

Unexpected Temperature Change

During chemical bonding, energy is released or absorbed making their surroundings hotter or cooler

Examples:

• Adding baking soda to vinegar causes the temperature to decrease.
• Body temperature increases to fight infections.

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In an unexpected temperature change, what causes the temperature change?

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Physical & Chemical Changes

Combustion/Burning

A chemical reaction between substances, usually including oxygen accompanied by giving off heat and/or light.

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This is a permanent change that cannot be undone.

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Examples:

• Wood burning
• Candle
• Rusting

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Physical & Chemical Changes

Precipitates Form

When a solid suddenly appears in a solution and settles to the bottom, collects on another object, or makes the solution cloudy

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Examples:

• Milk souring
• Bath tub rings

How can you tell that a precipitate has formed?

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Physical & Chemical Changes

Bubbles Form

When gases produced in a chemical reaction are released.

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Examples:

• Alka-Seltzer
• Bubbles released when vinegar and baking soda are combined

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Physical & Chemical Changes

Betty and her grandson decided to bake a cake. They gather eggs, flour, sugar, salt, baking soda, oil, and vanilla. All of the ingredients are measured and mixed following Betty’s grandmother's recipe. They bake the cake in the oven for 30 minutes. Did the ingredients undergo a physical change or chemical reaction? How do you know?

Think About It

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Hammering gold until it becomes flat

Melting Ice

Cracking an egg

Mixing 2 substances; a solid is formed at the bottom

When boiling water the water turns into steam

Baking a cake in the oven

Burning wood in a campfire

A bicycle sits out in the rain for a year and rusts

Dissolving salt in water

Combining 2 clear substances; solution created is bright yellow

Type your answer here

Type your answer here

Write a short definition for physical and chemical changes.

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Then sort the examples of these changes by clicking on and dragging the labels to the correct column. One of each has been done for you.

Adding an Alka-Seltzer to water and bubbles form

Change?

Change?

Tearing Paper

Change?

Change?

Change?

Change?

Change?

Change?

Change?

Change?

Last Look

Bill Nye

Give your best answer to...�

How does evidence of chemical reactions indicate that new substances with different properties are formed?

Check for Understanding

Still have questions?

Which parts of the essential question do you still need help to understand?

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