1. Double Replacement Reaction:
Parts of two compounds switch places to form two new compounds
Two reactants yield two products.

2. Al2(SO4)3 (s) + 3NH4OH (aq)
2Al(OH)3 (s) + 3NH4SO4 (aq)
MgSO4 (s) + 2NH4OH (aq)
Mg(OH)2 (s) + (NH4)2SO4 (aq)

3. + Synthesis ( 2 becomes 1) Decomposition (1 becomes 2)
Single Replacement
(new couple)
Double Replacement
(Swap ‘hats’)

4. Which type of reaction is shown?
2 Ca (s) + O2 (g)
2 CaO (s)
Synthesis
Cu (s) + 2 AgNO3 (aq)
Cu(NO3)2 (aq) + 2 Ag (s)
Single Replacement
MgCO3 (s)
MgO (s) + CO2 (g)
Decomposition
3AgNO3 (aq) + Na3PO4 (aq)
Ag3PO4 (s) + 3NaNO3 (aq)
Double Replacement

5. Zn (s) + 2HCl (aq) ZnCl2 (aq) + H2 (g) 2 HgO (s) 2Hg (l) + O2 (g)
Single Replacement
2 HgO (s)
2Hg (l) + O2 (g)
Decomposition
BaCl2 (aq) + Na2SO4 (aq)
BaSO4 (s) + 2 NaCl (aq)
Double Replacement
H2 (g) + Cl2 (g)
2 HCl (g)
Synthesis

6. Heat and Chemical Change

7. Ace Ice Melter RAPIDLY MELTS ICE AND SNOW AND PREVENTS RE‑FREEZING
Active Ingredients
KCl
NaCl
NH2CONH2 (urea)
C7O6H14 (methyl-D-glucopyranoside; a surfactant)
Ace Ice Melter
RAPIDLY MELTS ICE AND SNOW AND PREVENTS RE‑FREEZING
Ace Ice Melter features a special custom blend of superior ice melting ingredients. Together they melt even the most stubborn ice and snow and work to prevent re-freezing.
Melts ice down to 0°F (-18 °C).

8. What have we learned?
Sometimes heat is given off during a chemical reaction.
This makes it feel hotter.
Sometimes heat is absorbed during a chemical reaction.
This makes it feel colder.
What causes it to be different?

9. Chemical bonds contain energy.
Add the energy of all of the bonds in the reactants together to find their total energy.
Add the energy of all of the bonds in the products together to find their total energy.
If the two numbers aren’t the same (and they almost never are), then there will be heat energy given off or taken in.

10. 2 H2 + O2
2 H2O
2 H2 + O2
Energy barrier
2 H2O
Energy
If the products contain less energy, energy must have been given off during the reaction.

11. 2 H2O
2 H2 + O2
2 H2 + O2
2 H2O
Energy barrier
Energy
If the products contain more energy, energy must have been absorbed during the reaction.

12. Heat exits = exergonic = exothermic
If heat energy is given off during a reaction, it is called an EXERGONIC or an EXOTHERMIC REACTION.
Heat exits = exergonic = exothermic
Exergonic reactions can be recognized by a temperature INCREASE.

13. Heat enters = endergonic = endothermic
If heat energy is absorbed during a reaction, it is called an ENDERGONIC or an ENDOTHERMIC REACTION.
Heat enters = endergonic = endothermic
Endergonic reactions can be recognized by a temperature DECREASE.

14. Rates of Reactions
Vs.

15. Exploding Dust!? December 1977 in Westwood, LA
Grain elevator explosion
August 10, 2003 in Columbus, OH
Flour mill explosion
January 29, 2003 in Kinston, NC
West Pharmaceutical Services

16. Explosion = Fast Reaction Rates
flour
Flour
Pile
Slow
Rate of Reaction
Air-borne dust
???
[dust] > 50 g/m3
chemed.chem.purdue.edu/demos/main_pages/5.14.html

17. W This high school chemistry demo brought to you by:
NC Competency Goal 4.03
Assess reaction rates and factors that affect reaction rates.
And by the letter W