Unit 7: Chemical Reaction

the starting materials in a chemical reaction

• Products
• Reactants
• Starters
• Enders

a substance that is formed as the result of a chemical reaction

• Product 
• Reactant
• Starters
• Enders

a process or reaction in which the system absorbs energy from its surroundings; usually, but not always, in the form of heat

• Endothermic Reaction
• Exothermic Reaction
• Diffusion
• Fission

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.