Mixed Final Review HONORS

What criteria must be met for reactant collisions to result in a successful product?

• The reactants must collide with each other

• The reactants must collide with enough energy and be in the right positions

• The reactants must have enough energy to form the activated complex

During evaporation, water absorbs heat so that bonds can break and water vapor forms. This is an example of an _____________ reaction.

• endothermic

• exothermic

a chemical reaction that releases energy by light or heat

• Endothermic Reaction
• Exothermic Reaction
• Diffusion
• Fission

What is collision theory?

• Molecules must collide in the correct orientation with enough energy to bond.

• Molecules need enough energy to collide and react.

• Atoms constantly collide and react.

• The minimum energy needed for atoms to react

The Law of Conservation of Mass states

• that matter exists in all states and reacts the same
• that matter can only be changed into new substances by introducing a catalyst
• that matter exists in the same state throughout any chemical change
• that matter cannot be created or destroyed and that the mass of the products must equal the mass of the reactants

A student places a piece of a potato into a container of hydrogen peroxide. One observation the student makes is that bubbles form around the potato. The presence of bubbles might indicate the formation of a new substance because bubbles - 

• could show that a gas is forming
• always rise to the top of a liquid. 
• are almost always perfectly spherical.
• usually burst after a few minutes.

Hydrogen peroxide breaks down to form water and oxygen gas. Which observation is evidence that a chemical reaction has occurred?

• The mass of the solution remains the same.
•  Phase changes are observed.
•  The color of the solution remains clear.
• The temperature of the solution increases. 

A clear liquid from a flask is poured into another clear liquid in a beaker. Which of the following results of this procedure would indicate a new substance was formed?

• The level of the substance in the beaker is higher after the other liquid is added.
• A yellow solid forms and then settles to the bottom of the beaker.
• Small white crystals are left behind in the flask that held the first liquid.

Which of the following is an example that includes evidence of a chemical reaction?

• A sample of zinc is placed in water and it settles to the bottom
• A solid block of ice is heated and it completely melts into a liquid. 
• Sugar that is burned gives off an odor and turns brown and then black.
• A tomato is placed into a blender and chopped up into smaller pieces.

A precipitate is a 

• liquid that forms when two solids are reacted
• a solid that forms when two liquids are mixed
• a gas that forms when vinegar and baking soda react
• a change of color in a solution