Review 6.5C

What is true about ALL chemical changes?

• They all produces gas/bubbles/fizzing

• They all have a temperature change (hotter/colder)

• They all change colors

• They all produce NEW and DIFFERENT substances

A teacher shows the class two liquids that are both odorless and clear. When they mix together, solid gold chunks are formed. What change occurred and how do you know?

• A chemical change because a precipitate was formed

• A physical change because there was a color change

• A chemical change because an odor was produced

• A physical change because the volume increased when the two liquids were mixed together.

In class, a teacher places a balloon filled with baking soda over a flask filled with vinegar. When the powder falls into the flask and combines with the vinegar, the balloon inflates (fills up with air). What evidence is there that a chemical change occurs?

• The powder and liquid combine

• A gas is produced that fills up the balloon.

• There is no evidence that a chemical reaction to place

• The powder stayed solid so it is considered a precipitate

When I go to Chipotle I love to order guacamole. It smells amazing and tastes even better! Unfortunately, sometimes I don't eat it fast enough and it turns brown. Stirring it up hides the brown, but if it sits out longer, it continues to change. What indicates a chemical reaction in this scenario?

• The guacamole smells amazing

• The guacamole tastes incredible

• The guacamole turns a yucky brown color

• I stir the guacamole to get rid of the brown

Check all of the words that may indicate a Physical Change:

• Melting

• Freezing

• Burning

• Mixing

• Precipitate formed

Choose all of the words that may indicate a chemical change has occurred.

• Burning

• Evaporating

• Dissolving

• Odor change

• Energy change (sound,light, temp)

Iron rusts.

• Chemical change
• Physical Change

Ice Melting

• Chemical Change
• Physical Change

Pancakes cooking on a griddle

• Chemical Change
• Physical Change

Sugar dissolves in water

• Chemical Change
• Physical Change