Warm Up January 13, 2014

Balance and classify the following equations:• C + O2 CO2

• NH3 N2 + H2

• Zn + HCl ZnCl2 + H2

Correct Homework

A chemical reaction in which two or more simple substances combine to form a new, more complex substance.

A chemical reaction in that breaks down compounds into simpler products.

A chemical reaction in which one element replaces another in a compound or when two elements in different compounds trade places.

Correct Homework

The formula tells you the number and type of atoms present in a compound. The plus sign means “reacts with” and the arrow means “to produce”.

The reactants are found on the left side of the arrow and are the compound you start with before the reaction takes place. The products are new substances formed as a result of the reaction.

Synthesis Example: 2Mg + O2 2MgODecomposition Example: MgO 2Mg + O2 Replacement Example: 3CuCl2 + 2Al 2AlCl3 + 3Cu

The smallest possible number of products in a decomposition reaction is 2. If a reaction only has one product, it is a synthesis reaction.

Correct Homework

6 6 6

2 2

22

22

22

812

• Open and closed reactions can be exothermic or endothermic.

• Exothermic reactions- ADD energy to environment

• Endothermic reactions – TAKE energy from environment

Exothermic – The match ADDS heat/light energy to the environment

Endothermic – it TAKES energy from the environment to digest the sandwich

Controlling Chemical Reactions (6.3)

• All chemical reactions require a certain amount of energy to get started.

• This energy is called activation energy.

• This is Bob. It takes a lot of energy for Bob to get off the couch.

• But, once Bob does get off the couch and start running, it is easier for him to find the energy to keep running.

Activation Energy

• Bob’s activation energy looks like this:

Endothermic Reactions

Exothermic Reactions

Rates of Chemical Reactions

• The rate is the speed at which a chemical reaction happens.

• Factors that affect rate are surface area, temperature, concentration, and catalysts.

Surface Area

• Increasing surface area increases the rate of reaction.

Low Surface Area High Surface Area

Temperature

• Increasing temperature increases the rate of a chemical reaction.

Concentration

• Higher concentration increases the rate of a chemical reaction.

Catalysts

• Catalysts increase the rate of a chemical reaction by lowering the activation energy.

• Catalysts are not changed in a chemical reaction.

• This is Christina. She loves One Direction.

• Christina really wants One Direction autographs. But she is she and will need to build up the courage (activation energy) to ask for autographs.

• So her friend Brittany acts a s a catalyst and pushes Christina to the front of the crowd and catches the attention of One Direction for her, (lowering her activation energy).

Cool Down