1. Balancing Reactions

2. What is the difference between a chemical and physical change?
What is some evidence you might observe to know a chemical change has taken place?

3. Chemical Reactions
Process by which the atoms of one or more substances are rearranged to form different substances
What is some evidence you might observe to know that a chemical reaction has taken place?

4. What’s Involved 2 H2 (g) + O2 (g)  2 H2O (l)
Reactant – starting substance
Product – substances formed in the reaction +  ⇌
(s), (l), (g), (aq)

5. Word Equations Word Equation Skeleton Equation
Aluminum (s) + bromine (l)  aluminum bromide (s)
Skeleton Equation
Al (s) + Br2 (l)  AlBr3 (s)

6. Write the Skeleton Equations
Hydrogen (g) + bromine (g)  hydrogen bromide (g)
H2 (g) + Br2 (g)  HBr (g)
Carbon monoxide (g) + oxygen (g)  carbon dioxide (g)
CO (g) + O2 (g)  CO2 (g)
Challenge: When heated solid potassium chlorate yields solid potassium chloride and oxygen gas.
Potassium chlorate (s)  potassium chloride (s) + oxygen(g)
KClO3 (s)  KCl (s) + O2 (g)

7. Chemical Equations Chemical Equation
Statement that uses chemical formulas to show identities and relative amounts of the substances involved in a chemical reaction

8. Balancing Chemical Equations
Determine the reactants and products.
Write the formula for each reactant and product and tell its state of matter
Start with the reactants and count the total number of atoms present on each side
Determine which of the compounds need coefficients to balance both sides of the equation
Coefficient – the number written in front of a reactant or product
Double check your work

9. Balance __Na3PO4 (aq) + __KOH (aq)  __NaOH (aq) + __ K3PO4 (s)
__MgF2 (aq) + __Li2CO3 (aq)  __MgCO3 (s) + __LiF (aq)
MgF2 (aq) + Li2CO3 (aq)  MgCO3 (s) + 2 LiF (aq)
__P4 (g) + __ O2 (g)  __ P2O3 (g)
P4 (g) + 3 O2 (g)  2 P2O3 (g)

10. What are the steps for balancing a chemical Equation?
Balance the equation below. __VO(s) + __ Fe2O3 (s) __ FeO (s) + __ V2O5 (s) 2 VO(s) + 3 Fe2O3 (s) 6 FeO (s) + 1 V2O5 (s)

11. Word Equations
Solid zinc and lead (II) nitrate solution react to form zinc nitrate solution and solid lead.
Aluminum bromide solid and chlorine gas react to form aluminum chloride solid and bromine gas.
Potassium metal and chlorine gas combine to form solid potassium chloride.
Calcium hydroxide solution and phosphoric acid react to form calcium phosphate solid and water.

12. Answers Zn (s) + Pb(NO3)2 (aq)  Zn(NO3)2 (aq) + Pb (s)
2 AlBr3 (s) + 3 Cl2 (g)  2 AlCl3 (s) + 3 Br2 (g)
2 K (s) + Cl2 (g)  2 KCl (s)
3 Ca(OH)2 (aq) + 2 H3PO4 (aq)  Ca3(PO4)2 (s) + 6 H2O (l)