Writing and Balancing Chem Rxn’s

KI and Pb(NO3)2

1. Was a gas formed?

2. Was Energy given off?

3. Was there a color change?

4. Did a precipitate form?

Writing Equations

• Reactants: What you start with.

KI and Pb(NO3)2

• Products: What you end with

KNO3 and PbI2

Equation

KI + Pb(NO3)2 KNO3 + PbI2

Reactants Products

Is every atom balanced???????

Law of Conservation of Mass/Matter

Mass/Matter cannot be created or destroyed it can only be transformed.

AKA=What you start with you must end with.

Balanced???

KI + Pb(NO3)2 KNO3 + PbI2

A number needs to go in front to change the number of molecules. We can bring in or create as many molecules as we want. WE CANNOT BREAK ANY BONDS!

Balancing Rules

1. Count the atoms on each side of reaction2. Pick one atom and go to the side with

fewer atoms.3. Place a coefficient in front of that

molecule to balance number of atoms.4. Re-calculate5. If not balanced, repeat step 2 for all

atoms.