Physical/Chemical Change

Physical/Chemical Change

Physical Change

• Change in the substance BUT NOT the substance itself.

• Believe it or not, this is just a physical change! Hot water poured into liquid nitrogen causing the nitrogen to evaporate very quickly and the water to condense, forming giant clouds of nitrogen gas and water droplets.

Chemical change

• The change from one set of substances into another.

• NEW Substance is formed!

• Evidence: New smell, new color, new gas or solid formed, change in temp.

• Elephant Toothpaste: Hydrogen peroxide + dish soap + Potassium Iodide. The hydrogen peroxide (H₂O₂) decomposes into water and oxygen gas, which is the foam. Potassium iodide acts as a catalyst and speeds up the reaction. Evidence: New Gas (oxygen) forms foam and heat is produced. (the color comes from food coloring, not the reactions)

Multiple Choice

The difference between a Physical change and a Chemical change is…

• Physical change is only a change to the outside appearance.

• Chemical change is when matter is changed into something new.

• Atoms are rearranged in chemical changes & not in physical.

• All are correct.

Multiple Choice

When a new substance is formed with different properties than the original substance it is called a...

• Chemical change

• Physical change

• Change in State

• Change in appearance only.

Multiple Choice

Which of the following could indicate that a chemical change took place?

• Change in color

• Production of Heat

• Formation of Gas

• All are correct

Multiple Choice

A change in which NEW substances are formed.

• Chemical change

• Physical change

Multiple Choice

Which is not a clue that could indicate a chemical change has occurred?

• Change in color

• Change in shape

• Release of energy/heat

• Formation of an odor

Multiple Choice

Identify the change shown in the picture. (Sparkler burning)

• Physical change

• Chemical change

Multiple Choice

Is Gatorade powder dissolving in water physical or chemical change?

• Physical 
• Chemical

Multiple Choice

Ripping up paper ...

• Chemical Change
• Physical Change

Multiple Choice

Bubbles form when two or more substances are combined ...

• Chemical Change
• Physical Change

Multiple Choice

Chemical or Physical change?

• Chemical

• Physical

Multiple Choice

On a camping trip, Mrs. Benavides roasts a marshmallow in the campfire. She notices that the roasted marshmallow smells and tastes differently than the uncooked marshmallows. What change has taken place, and how does Mrs. Benavides know?

• a chemical change because the marshmallow changed in taste, color and smell

• no change because the marshmallow is not a new substance

• only a physical change because the marshmallow changed in size

• a chemical change because the marshmallow only changed in pH level

Multiple Choice

Which is an example of a physical change?

• iron rusting

• charcoal burning

• an ice cube melting

• a marshmallow burning

Multiple Select

Which of the following are examples of a Chemical Change?

• Iron Rusting

• Gas Burning

• Breaking a glass

• Boiling water

• Burning Wood

Multiple Choice

A green powder is heated & a gas is given off while it turns to a black solid. This describes

• Physical Change

• Chemical Change

• Change in State

• Change in Temperature

Multiple Choice

Chocolate chips are melted in a pot on the stove.

• Physical Change

• Chemical Change

Multiple Choice

A metal wagon is left out in the rain and it starts to rust.

• Physical Change

• Chemical Change

Multiple Choice

Breaking a watermelon into pieces.

• Physical Change

• Chemical Change

Multiple Choice

Ice cream melting on a hot summer day.

• Physical Change

• Chemical Change

Multiple Choice

Sodium metal and chlorine gas react to form salt.

• Physical Change

• Chemical Change

Multiple Choice

Digesting food (food being broken down in the stomach).

• Physical Change

• Chemical Change

Multiple Choice

Before a basketball game the ref uses an air pump to inflate the ball.

• Physical Change

• Chemical Change

The Law of Conservation of Mass

• Matter cannot be created nor destroyed

• The mass before and after a reaction is always the same!

• Mass of the reactants (what you have before) = Mass of the products (what you get)

• Picture shows 2H₂+O₂ = 2H₂O

Multiple Choice

Fill in the blank:
The law of conservation of mass states that matter cannot be created nor __________________.

• destroyed

• rearranged

• transferred

• changed

Multiple Choice

How does the total amount of matter before a chemical reaction compare to the total amount of matter after the reaction?

• The amount of matter is greater before the reaction.

• The amount of matter is greater after the reaction

• The amount of matter before and after the reaction is the same.

• There is no relationship between the amount of matter before and after the reaction.

Multiple Choice

A 500-gram block of solid cheese is melted in a pot. Which is most likely the mass of the cheese after it is melted?

• 500 grams, because the cheese does not gain or lose mass just because it was melted
• 499 grams, because some of the cheese evaporates as it melts
• 502 grams, because the cheese absorbs heat as it melts

Multiple Choice

A scientist mixed 100 grams of salt into a 500 grams of water. How many grams of salt water did I make?

• 500g

• 400g

• 600g

• 700g

Multiple Choice

4 grams of hydrogen and 32 grams of oxygen will combine to form:

• 36 grams of water

• 28 grams of hydroxide

• 32 grams of oxygen

• 36 grams of deuterium

Multiple Choice

A 55-gram egg is placed in a pot. After the egg is boiled, which is most likely the mass of the egg?

• 50 
• 55