Cycle 8 CFA Review

What is the difference between reactants and products?

• Reactants are substances that start a chemical reaction, and products are substances that are produced in the reaction

• There is no difference.

• The reactants are the substances that end the chemical reaction. The products are the substances that begin the chemical reaction.

Name three properties that can be observed in a substance.

• Color

• Melting and boiling point

• Density

• Atomic number

How does the Law of Conservation of Matter apply to chemical reactions?

• Only Newton's Law applies to chemical reaction.

• The mass and number of atoms remain the same.

• The mass doubles and the atoms remain the same.

Jason observes a process in an industrial facility. The process begins by mixing the first and second substances; after a while, the third substance is also observed. Based on the data in the table, which statement describes the process that is occurring?

• No change occurs when the first two substances combine.

• A physical change occurs when the first two substances combine.

• A chemical change occurs when the first two substances combine.

• A change occurs at the macroscopic, observable level, but no change occurs at the microscopic, molecular level.

How does a catalyst affect a chemical reaction?

• Slows it down

• No affect

• Speeds it up

• Changes its color

The diagram shows a chemical reaction. What is represented in box C?

• atom

• product

• element

• reactant

If you have 12 atoms of hydrogen before a chemical reaction, how many atoms of hydrogen will be present after the chemical reaction?

• 1

• 7

• 22

• 12

Which observation is a sign of a chemical change?

• A rotting potato gives off a bad smell.

• A melting block of ice leaves a large puddle.

• A cloud changes shape when blown by the wind.

• A plaster statue breaks when it falls onto the floor.

There are several differences between chemical and purely physical changes. Which process is an example of a chemical change?

• steam rising from a boiling pot of soup

• alcohol evaporating from a cotton swab

• a piece of wood shrinking as it dries out

• a metal railing rusting in damp weather

Trini adds 10 g of baking soda to 100 g of vinegar. The mixture begins to bubble. When the bubbling stops, Trini finds the mass of the resulting mixture. She determines its mass is 105 g. Her data are in the table.

• A gas has formed and left the mixture.

• Vinegar evaporated during the experiment.

• Mixtures always are less massive than their parts.

• Mass was destroyed when the vinegar reacted with the baking soda.