CATEGORY 1: CLASSIFY THAT MATTER!
This type of matter contains only one type of substance and has a definite composition.
What is a pure substance?
In which phase are particles packed closely together and mainly vibrate in place?
What is a solid?
Ice melts into liquid water. Physical or chemical?
What is a physical change?
Heat naturally flows from an object with a ______ temperature to an object with a ______ temperature.
What are higher → lower temperatures?
An endothermic reaction ______ thermal energy.
What is absorbs?
Water (H₂O) is made of hydrogen and oxygen atoms that are chemically bonded together. What type of matter is it?
What is a compound?
Which phase has particles that are spread far apart and move freely?
What is a gas?
A piece of paper is cut into smaller pieces. Physical or chemical?
What is a physical change?
A hot cup of cocoa sits on a table. Which direction does thermal energy move?
What is from the hot cocoa to the cooler surroundings?
An exothermic reaction ______ thermal energy.
What is releases?
You mix salt and water together. The salt seems to disappear, but the substances are not chemically bonded. What type of mixture is this?
What is a homogeneous mixture?
A substance changes from a solid into a liquid. What phase change is occurring?
What is melting?
A piece of iron begins to rust. Physical or chemical?
What is a chemical change?
What happens when two objects reach thermal equilibrium?
What is they reach the same temperature and there is no net heat flow between them?
You touch the container after a reaction and it feels warmer. Is the reaction more likely endothermic or exothermic?
What is exothermic?
Trail mix contains pieces of several different foods that you can see separately. What type of mixture is it?
What is a heterogeneous mixture?
A substance changes from a gas into a liquid. What phase change is occurring?
What is condensation?
A substance produces a gas, changes color, and forms a new substance during a reaction. Physical or chemical?
: What is a chemical change?
True or False: Heat naturally flows from a colder object to a hotter object.
What is false?
You touch the container after a reaction and it feels colder. Is the reaction more likely endothermic or exothermic?
What is endothermic?
A sample contains two or more substances that are physically combined, and you can see different parts of the sample. What classification best describes it?
What is a heterogeneous mixture?
Tricky
Water is boiling. Is the water undergoing a physical or chemical change? Explain why.
What is a physical change, because the substance remains water even though its state changes?
Challenge
A student says, “If I can't see a new substance being made, it must be a physical change.” Is the student always correct?
No. The appearance of a change alone doesn't necessarily tell you whether it is physical or chemical. You need evidence that a new substance has formed.
Tricky
You hold an ice cube in your hand. Your hand feels cold because thermal energy is moving in which direction?
What is from your hand to the ice cube?
Challenge
In an exothermic reaction, compare the energy of the reactants to the energy of the products.
The products have less energy than the reactants because energy was released.