1. Describing Chemical Reactions Lesson 9

2. Chemical Equations
Chemical equation is a short easy way to show a chemical reaction using symbols instead of words
Use chemical formulas and symbols to summarize a reaction
Formulas
H2O
CO2
C12H22O11

3. Fill in the blank
Chemical equations use ________________ and ______________ to summarize a reaction
Examples of a ______________________ is CO2 and __________
Chemical formulas, symbols, chemical formula, h2o

4. Structure of an Equation
All chemical equation have a common structure
Starting substances  reactants
New substances  products
Reactant + Reactant  Product + Product
CaCO3  CaO + CO2

5. Fill in the blank
The substance you start with in a chemical reaction is called the ________________
When the reaction was complete, you have a new substance called the _________________
Reactants, products

6. Conservation of Mass
States that during a chemical reaction, matter is not created or destroyed
All atoms present at he star of the reaction are present at the end
States that in a chemical reaction, the total mass of the reactants must equal the total mass of the products

7. Fill in the Blank
The _____________________ states that matter is not created or destroyed
the total mass of the ____________ must equal the total mass of the ______________
Conservation of mass, reactants, products

8. Opened and Closed Systems
Open system: matter can enter from or escape to the surroundings
Ex. Burning wood in a fire place
Products of the wood fire have escape up the chimney and into the room
Closed System: matter is not allowed to enter or leave
Ex. Apple decaying under a glass dome
Products from decay are contained by the glass dome

9. Fill in the blank
In an _______________ matter can enter or escape into is surroundings
In a __________________ matter can’t escape
Open system, closed system

10. Open or closed system Water boiling on the stove in a pot
Water boiling on the stove in a pot with a lid