12/8 - 8th Grade Agenda

Learning Objective: Learn about Fire SafetyCollect HW: Reading & Notetaking: p.117 – 118Textbook Reading p. 237-245HW: Reading & Notetaking p.119 – 122Reminder HW: Science Fair Background due 1/14 & 1/15 (10 Points)

Daily Reflection

• Prompt: What is the difference between an exothermic and endothermic reaction?

What is Conservation of Mass?• The total mass of the reactant must equal the

total mass of the products• During a chemical reaction, matter is not

created or destroyed

Open End vs Closed End systems

What is a coefficient

•2H2 + O2 2H2O

• The number in front of a chemical formula in a chemical is called an coefficient

• It tells you how many molecules or atoms of each reactant or product take part in the reaction

What is a Chemical Equation

• Reactant + Reactant Product + Product

• H2 + O2 H2O2

• Subscript shows the number of atoms of an element in a molecule

Balancing Equation

Types of Chemical ReactionsWhat is a Synthesis?

• When two or more substances (elements or compounds) combine to make a more complex substance, the process is called a synthesis

Types of Chemical ReactionsWhat is Decomposition?

• Decomposition reaction breaks down compounds into simpler products

What is a Replacement reaction?

• It is similar to a girl switching boyfriends

• A reaction in which one element replaces another in a compound

What is an activation energy?

• The minimum amount of energy that has to be added to start a reaction.

• Think of a chemical reaction as being like a rock resting behind a ridge at the top of a hill.

Energy in Chemical Reactions

• Every chemical reaction involves a change of energy. (In the test)

What affects the rate of chemical reactions?

• Concentration• Surface Area• Temperature• Catalysts

What is a Catalyst?

• A Material that increases the rate of a chemical reaction by lowering the activation energy

• What does it mean?

Catalyst Demonstration

• Paper clips represents reactants

• If I place two paper clips in a cup, no matter how hard I shake the cup, I can not get the paper clips to link up.

Catalyst Demonstration

In this model,Paper clip = ReactantDollar bill = Catalyst

Another Catalyst Demonstration

• Hydrogen Peroxide decomposes into Water and Oxygen slowly

• 2H2O2 -> 2H2O + O2

• Yeast acts as a Catalyst and speeds up the reaction.

What is an enzyme or catalyst?

• Enzyme is biological catalyst which provide a surface on which reactions take place.

• This helps reactions happen at lower temperatures because it lowers activation energy.

What is combustion?

• Combustion is a rapid reaction between oxygen and a substance called a fuel.

What are the three things necessary to start and maintain a

fire?• Fuel

• Oxygen

• Heat

What are four common sources of fires at home?

• Small heaters• Fires in the kitchen• Faulty electric wiring• Carelessness with

cigarettes.

How can you fight a fire?

• A. Blow air on it?

• B. Cover it with baking soda?

• C. Use a fire extinguisher?

• D. Pour water on it?

Which of the following is a safety aid in a fire safe home.

• A) smoke detectors

• B) gasoline can in the basement

• C) Fire extinguishers

• D) Box of baking soda in the kitchen