1. Chemical Changes – Part Deux

2. Types of chemical changes
Synthesis & Decomposition
Precipitation
Oxidation
Combustion
Acid-Base Neutralization
Cellular Respiration & Photosynthesis

3. 1. Synthesis and Decomposition
Synthesis Reaction: The combination of two or more reactants to form a new product
Decomposition: The separation of a compound into two or more compounds or elements
2H2 + O2  2H2O A + B  AB 2H2O  2H2 + O2 AB  A + B

4. 2. Precipitation

5. 2. Precipitation
CdSO4 (aq) + K2S (aq) → CdS (s) + K2SO4 (aq) 2 NaOH (aq) + MgCl2 (aq) → 2 NaCl (aq) + Mg(OH)2(s) CuSO4 (aq) + 2NaOH (aq) → Cu(OH)2 (s) + Na2SO4 (aq)

6. 2. Precipitation
Formation of an insoluble, or only slightly soluble, solid substance (precipitate), when two aqueous solutions are combined

7. 3. Oxidation

8. Oxidation
Chemical change involving oxygen or a substance with properties similar to those of oxygen

9. 4. Combustion – a type of oxidation
Form of oxidation that releases a large amount of energy

10. 5. Acid-Base Neutralization
Reaction of an acid with a base to form a salt and water
Acid (aq) + Base (aq)
Salt (aq) + Water (l)
If H+ = OH- ?
If H+ > OH- ?
If H+ < OH- ?
H+ ions
OH- ions

11. Heart Burn
Stomach Acid + Antacid
Salt + Water

12. Neutralization of HCl and NaOH
HCl (aq) + NaOH (aq)
NaCl (aq) + H2O (l)
HCl (aq)
H+ (aq) + Cl- (aq)
NaOH (aq)
OH- (aq) + Na+(aq)
H2O
NaCl

13. Recognizing Acid-Base Neutralization Reactions
HCl (aq) + NaOH (aq)
NaCl (aq) + H2O (l)