1. CHEMICAL REACTIONS

3. chemical reaction
a reaction during which substances change into one or more new substances with different physical and chemical properties
reactants  products

4. Law of Conservation of Matter
in any chemical reaction, the mass of the products is always equal to the mass of the reactants, matter can't be created or destroyed

5. Types of Chemical Reactions
1. Synthesis Reactions
the combination of two or more simple substances to form a more complex substance
also known as combination or addition reaction
A + B  AB
ex. H2 (l) + O2 (l)  H2O (g)

6. Challenger disaster, 1986…

7. special case of synthesis: Combustion Reaction
if oxygen rapidly reacts with another element it can form a more complex compound by burning
C(s) + O2 (g)  CO2 (g)
S (s) + O2 (g)  SO2 (g)

8. 2. Decomposition Reactions
the breakdown of large, more complex molecules or ionic compounds into smaller and simpler entities
AB  A + B
ex H2O2 (l)  O2 (g) H2O (l)
(hydrogen peroxide)
Coefficient up front tells you that there are two H2O2

10. Writing Chemical Equations
word equation
identifies reactant and product by name,
ex. sodium + chlorine  sodium chloride
skeleton equation
lists reactants and products with + and signs, shows state
ex. Na (s) + Cl2 (g) --> NaCl (s)
balanced chemical equation
reflects the law of conservation of mass
ex. 2 Na(s) + Cl2 (g) --> 2 NaCl

11. Steps in Balancing Chemical Equations
1. is the skeleton equation accurate?
2. balance atoms on both sides, other than H and O
3. polyatomic ions are balanced as a whole IF whole on both sides
4. balance H, O
5. balance lone elements, ex. Cl2
6. check!

12. ex1. sulfur dioxide gas reacts with oxygen gas to produce gaseous sulfur trioxide

13. ex2. when dissolved in water, copper (II) nitrate reacts with potassium hydroxide to form a water-soluble potassium nitrate and solid copper (II) hydroxide precipitate

14. In Groups Balance
1. KOH + SO2 --> K2SO3 + H2O
2. Al4C3 + H2O --> Al(OH)3 + CH4
3. Na2CO3 + H3PO4 --> Na3PO4 + H2O + CO2
4. CaC2 + H2O --> Ca(OH)2 + C2H2
5. Al + NaOH --> Na2AlO3 + H2
6. KNO3 --> KNO2 + O2

15. 3. Single Displacement Reactions
reaction of an element and a compound to produce a new compound
ex. AB + C  AC + B

16. ex. solid zinc in lead (II) nitrate solution will give you solid lead and aqueous zinc nitrate

17. 4. Double Displacement Reactions
a chemical reaction in which two compounds in aqueous solution react to form two new copounds
AB + CD  AD + CB

18. ex. aqueous silver nitrate + aqueous calcium chloride  silver chromate + calcium nitrate

19. precipitate
a solid that forms as a result of a chemical reaction between two aqueous solutions
use the solubility chart to identify which one!