1. Chapter 11 Chemical Reactions

2. Hindenburg Ship
Hydrogen gas combined with Oxygen which caused the ship to catch fire

3. Chemical reactions
Take place after you eat

4. Photosynthesis

5. In a Chemical reaction
One or more substances change into one or more new substances

6. Writing chemical equations
Word Equations
Reactants
Products
Iron + Oxygen
Iron(III) Oxide
Hydrogen Peroxide
Dihydrogen monoxide Oxygen
Methane + oxygen
Carbon dioxide + Dihydrogen monoxide

7. Chemical Equations Skeleton Equations
- Equation that does not show the amounts of the reactants and the products
Fe + O2
Fe2O3
Unbalanced equation !!!!!

8. One can add more information to the skeleton equations:
To indicate if the reactants and products are liquids, solids or gases you use parentheses
Fe(s) + O2(g)
Fe2O3 (s)
To indicate a catalyst (a substance that speeds up the reaction but is not used in the reaction) you place the catalyst over the arrow
MnO2
H2O2 (aq)
H2O (l) + O2 (g)

9. Used to separate two reactants or two products “yields”
Symbol
Explanation +
Used to separate two reactants or two products
“yields”
Reaction is reversible
(s)
Solid state
(l)
Liquid state
(g)
Gaseous state
(aq)
Aqueous solution, dissolved in water
Heat is applied to reaction
Catalyst used in reaction
heat
catalyst

10. Balancing Equations Reactants Products
Frame + wheel + hanlebar + pedal
Bicycle
F + 2 W + 1 H + 2 P
FW2HP2

11. Balanced!! Calcium + Oxygen Calcium Oxide
First write the skeleton equation
Ca + O2
CaO
Now balance
Balanced!! 2
Ca + O2 2
CaO 2
1 Ca 2
1 Ca 2O 2
1 O

12. Balanced!! Hydrogen + oxygen Dihydrogen monoxide
First write the skeleton equation
H2 + O2
H2O
Now balance 4
2 H
2 H 4
2 O 2
1 O
Balanced!! 2
H2 + O2 2
H2O

13. Types of Chemical Reactions
combination
decomposition
Single-replacement
Double-replacement
combustion

14. Combination Reactions (Synthesis)
Chemical change in which two or more substances react to form a single new substance
2 Mg(s) + O2(g)
2 MgO(s)
Metal +
nonmetal
2 K(s) + Cl2(g)
2 KCl(s)
SO2 (g)
S (s) + O2(g)
Two nonmetals
two possibilities
2 S (s) + 3 O2(g)
SO3 (g)

15. **Requires heat or electricity
Decomposition Reactions
Chemical change in which a single compound breaks down into two or more simpler products
**Requires heat or electricity
2 HgO(s)
heat
2 Hg(l) + O2(g)
2 H2O(l)
electricity
2 H2(g) + O2(g)

16. Single-replacement Reactions
Chemical change in which one element replaces a second element in a compound
Zn(s) + H2SO4(aq)
ZnSO4(aq) + H2(g)
Cl2(g) + 2 NaBr(aq)
2NaCl(aq) + Br2(aq)

17. Double-replacement Reactions
Chemical change involving an exchange of positive ions between two compounds
2 NaCN(aq) + H2SO4(aq)
2 HCN(aq) + Na2SO4(aq)
NaOH(aq) + Fe(NO3)3 (aq)
Fe(OH)3(s) + 3 NaNO3(aq)
**Solution containing two ionic compounds

18. Combustion Reactions
Chemical change in which an element or compound reacts with oxygen often producing energy in the form of heat or light
CH4 (g) + 2 O2(g)
CO2 (g) + 2 H2O(l)
2HCOOH (aq) + O2(g)
2CO2 (g) + 2 H2O(l)
hydrocarbon + oxygen  carbon dioxide + water

19. ** The number of elements and/or compounds reacting is a good indicator of possible reaction types and possible products- you can make predictions

20. Check what you know!! What are the five different types of reactions?
What type of reaction are the following?
C3H6 + O2 → CO2 + H2O
Li + O2 → Li2O
Zn + AgNO3 → Ag + Zn(NO3)2
Combination, decomposition, single-replacement, double-replacement, combustion
Combustion
Combination
Single-replacement

21. Predict the type of reaction that will occur?
An aqueous solution of two ionic compounds.
Reactant is a single compound.
The reactants are two elements.
The reactants are oxygen and a compound of carbon and hydrogen.
Double-replacement
Decomposition
Combination
Combustion

22. Many important reactions take place in water
Reactions in Aqueous Solution
Net Ionic Equations
Many important reactions take place in water
Net ionic equations are different that the equations we are used to writing. We used to write equations like this:
AgNO3(aq) + NaCl(aq) → AgCl(s) + NaNO3(aq)

23. Complete Ionic Equations
Shows the dissolved ionic compound as separate ions
Ag+(aq) + NO3-(aq) + Na+(aq) + Cl-(aq)
AgCl(s) + Na+(aq) + NO3- (aq)
Spectator ions -
Ion that appears on both sides of the equation but is not involved in the reaction
Net Ionic Equations
Equation that shows only the particles that are directly involved in the reaction
Ag+(aq) + Cl-(aq)
AgCl(s)

24. Predicting the formation of a precipitate
Compounds
Solubility
Salts of alkali metals and ammonia
Soluble
Nitrate salts and chlorate salts
Sulfate salts, except compounds with Pb, Ag, Hg, Ba, Sr, Ca
Chloride salts except compounds with Ag, Pb, Hg
Carbonates, phosphates, chromates, sulfides and hydroxides
Insoluble

25. First write the complete ionic equation
Check what you know!!!
Write a balanced net ionic equation.
Pb(NO3)2(aq) + H2SO4(aq) → PbSO4(s) + HNO3(aq)
First write the complete ionic equation
Pb2+(aq) + NO3- (aq)
+ H+(g) + SO42-(aq)
PbSO4(s)
+ H+(g) + NO3- (aq)
Then find the spectator ions and cross them out
Finally, write the net ionic equations
Pb2+(aq)
+ SO42-(aq)
PbSO4(s)