1. safety Always: Wear goggles Wear lab gear Hair up Wear closed shoes
NO playing
Monitor experiments
Check before turning the gas on
Call the teacher if there is a problem – IMMEDIATELY
Know where safety gear is
Rinse off chemical simmediatley
Follow all directions
safety
Bottle Safety.flv

2. Chemical reactions

3. chemical reaction reactant product physical change chemical change chemical equation mitochondria chloroplast exothermic endothermic
You should be able to identify and describe the following:
a chemical reaction
the difference between a chemical and physical change
the components of a chemical equation
exothermic versus endothermic reactions
Vocabulary & Goal

4. Chemical versus physical changes
Chemical changes
Physical changes
During this change the substance made is chemically different from what you started with
The change cannot be reversed
Clues:
Smoke
Sound
Color change
Gas is produced
There is a
change in size or shape
change in state (solid, liquid, or gas)
The change can be reversed
Chemical versus physical changes

5. Your turn: physical or chemical changes explain your reasoning.
Glass breaking
Hammering wood together to make a house
Spoiling food (what happens when you have milk for too long)
Melting butter
Burning toast (bread in the toaster for too long)
Cutting grass
Digestion of food
Mixing salt and water

6. occurs when ingredients combine, interact, are rearranged, and new substances are made.
More scientifically: in a chemical reaction you combine reactants (the original ingredients) to create a final product (what you get at the end of the chemical reaction)
A chemical change has occurred.
Chemical reaction

7. Chemical equation
describes the reactants and products of a chemical reaction Reactants -the chemicals you start with & are written on the left side of the chemical equation Products - the chemicals that are made & are written on the right side of the chemical equation

8. Ingredients
Reactants and products can be elements, compounds, or mixtures.
An element is an atom. More on these later.
A compound is made of more than one element bonded together. More on these later.
A mixture is made of elements and/or compounds stirred together but not bonded

9. Therm – means heat or energy
Endothermic
Exothermic
Exo- means out or to exit In an exothermic reaction – energy is released. Temperature of the surroundings increases (feels hot) Light may be emitted Why? When atoms bond together they release heat
Endo –means inside or to enter In an endothermic reaction – more energy is absorbed than released Temperature of the surroundings decreases (feels cold) Why? Atoms need to absorb heat to break their bonds

10. Endothermic or Exothermic? Why?
Your turn – identify each as endothermic or exothermic reaction and explain your reasoning
Activity
Endothermic or Exothermic? Why?
making ice cubes *
melting ice cubes *
cooking an egg
burning wood
Liquid water turning into steam (evaporation) *
rusting iron
* = not a chemical reaction

11. Pre-Lab Information
How to measure pH to see if a liquid is an acid or alkaline
Use a glass rod to take out a small sample of the liquid
Transfer the sample to the litmus paper
Wait 30 seconds
Compare color to sheet
Record pH and whether the liquid is acid (pH < 7), neutral (pH = 7), or alkaline (pH >7)
Safety
Goggles, lab coat, and hair up

12. Identity the Reactants
Chemical Equation:
Identity the Reactants
Identity the Products
Elements, compounds, or mixtures?
Color of litmus paper
Acid or alkaline?
Brief description of the method
Observations: sight, smell, feel, etc.
Was this an exothermic or endothermic reaction? How did you know this?
Did a physical or chemical change occur during this reaction? How do you know?

13. HW: read pages 7-8 in packet describing common chemical reactions and balancing equations