1. Chemical Reactions and Equations
Mr. Guerrero, La Feria High School

2. Chemical Change-any change in the way that atoms are bonding.
A chemical change always forms new substances.
Chemical Changes are called reactions and can be represented with a chemical equation.
Law of Conservation of Mass- during an ordinary chemical reaction, matter(mass) is neither created nor destroyed.

3. All chemical equations have 3 parts:
Reactants-going to react
Yield Sign-during the change
Products-the form of matter after the reaction
Reactant(s)  Product(s)

4. Symbols used in equations:
+ “and”
Yield sign, creates
(s) Solid
(l) Liquid
(g) Gas
(aq) aqueous solution(substance is dissolved in water)
reversible reaction
add heat to start reaction
Pt catalyst is present

5. 5 Types of Chemical Rxns:
1) Synthesis(Combination) X Y  XY
2) Decomposition(Breaks down) XY  X Y
3) Single Replacement A BC  B AC
*A must have a HIGHER activity than B, See page 278
4) Double Replacement AB + XY  XB + AY
(metathesis rxn)
5) Combustion(complete) ________ + O2  CO H2O

6. Identify the type of rxn and balance:
heat NH3(g)  N2(g) H2(g)
Mg(s) CuSO4(aq)  Cu(s) MgSO4(aq)
  P4(s)  +   O2(g) →   P2O5(s) + heat
C6H6(g) +   O2(g) →   CO2(g) +   H2O(g)
Ca(OH)2(aq) +   H3PO4(aq) →   Ca3(PO4)2(s) +   H2O(l) kJ

7. Identify the type of rxn and balance:
Cr(s) +  O2(g) →  Cr2O3(s)
AgNO3(aq) +  K3PO4(aq) →  Ag3PO4(s) +  KNO3(s)
Al(s) Fe2O3(aq)  Fe(s) Al2O3(aq) heat
C3H8(g) +  O2(g) →  CO2(g) +  H2O(g)
 heat Al2O3(s) →  Al(s) +  O2(g)