1. Balancing, Molar Mass, % Composition, Scientific Notation
Unit 4 – Part 1

2. What is a Chemical reaction
Chemical Reactions
Substances change into new substances
How Do You Know A Chemical Reaction Has Occurred?
Gives off heat (feels hot) or absorbs heat (feels cold)
Give off light
Produces a gas (it bubbles)
Forms a precipitate (2 liquids mix and a solid forms)
Changes color

3. What is a Chemical reaction
General Stuff about Chemical Reactions
Can be written in words or symbols
Always obeys Law of Conservation of Mass – matter cannot be created or destroyed
Reactants – ingredients – left side o f arrow
Products – cookies – right side of arrow

4. How to Balance a Chemical Reaction
Always start with good formulas
Must have equal numbers of each atoms on left and right side of arrow
Can NEVER CHANGE the subscripts
You can only change COEFFICIENTS

5. How to Balance a Chemical Reaction
_____P _____H2 → _____P4H10
_____PbO2 → _____PbO + _____ O2
___Zn(OH) ___H3PO4 → ___Zn3(PO4) ___H2O

6. How to Balance a Chemical Reaction
____NaCl ____H2SO4 → ____Na2SO ____HCl
____H ____ Fe3O4 → ____ Fe ____ H20