1. CHEMICAL REACTIONS

2. Chemical Equations Reactants – substances that undergo changes
Products – new substances formed from reaction
Reactants Products
N2 + 3H NH3

3. Conservation of Mass *Mass is not created in chem. reaction
*Mass in not destroyed in chem. Reaction

4. Types of Reactions Synthesis Decomposition Single-replacement
Double-replacement
Combustion

5. Synthesis Two or more substances react to form a single substance
A + B AB
Example: 2H2 + O H2O

6. Decomposition
A compound breaks down into two or more simpler substances
Reactant MUST be a compound!
Products may be elements or compounds
AB A + B
2H2O H2 + O2

7. Single Replacement
One element takes the place of another element in a reaction
A + BC B + AC
Cu + 2AgNO Ag + Cu(NO3)2

8. Double Replacement
Two different compounds exchange positive ions to form two new compounds
AB + CD AD + CB
CaCO HCl CaCl2 + H2CO3

9. Combustion Substance reacts with oxygen Often creates heat and light
CH4 + 2O CO2 + 2H20

10. Internal Combustion Engine

11. Reaction Rates
Reaction Rate – rate at which reactants change into products over time.
TNT vs Leaves changing

12. Reaction Rates ~ 200 – 350 calories
-A Cal X-Country runner burns calories- energy is released OR
-Just burn the bar!
-energy released faster!
**Same amount**

13. Factors affecting reaction rates…
An increase in TEMPERATURE increases reaction rate.
Decrease in temp = decrease in reaction rate.

14. Surface area
Increase in surface area of a reactant increases reaction rate.(and vice versa)

15. Stirring
Stirring reactants increases reaction rate.

16. Concentration
The more reacting particles, the more likely a reaction will occurr.
Concentrated detergent
Grape juice concentrate

17. Catalysts
Catalyst – substance that affects reaction rate without being used up.
Making friends…

18. Equilibrium When opposing changes take place at the same rate.
Physical and Chemical equilibria.
Reversible Reaction:
A + B C

19. Reactions… Exothermic – releases energy to its surroundings.
Warm test tube???
Endothermic – absorbs energy from surroundings.

20. MOLES
Mole – amount of a substance that contains ~ 6.02 x 1023 particles of that substance
Avagadro’s number (don’t worry about it.)
Marbles?

21. Mole vs. Dozen Eggs vs. Donuts
A dozen eggs has a different mass than a dozen donuts.
*But its still a dozen!
**A mole works the same as a dozen**

22. Molar Mass *The mass of one mole of a substance = molar mass
*Molar Mass = same as Atomic Mass but expressed in Grams!
??? What’s the molar mass of Carbon???
???Sulfur???

23. Mole - Mass Conversions
CO2 = ~ 44 grams
C = ~ 12 grams
O2 = ~ 32 grams
Conversion Factor:
44.0g CO OR 1 mol CO2
1 mol CO g CO2

24. Mole Conversions… Say you have… 50g of CO2
How many moles of CO2 do you have???
Use conversion factor:
50g CO2 X 1 mol CO2 = g CO2
44.0g CO g CO2
ANSWER = 1.14 moles of CO2

25. Converting… Convert 1.25 mol MgCl2 to grams!
1. Find out 1 mole of MgCl2 by adding atomic mass of each element.
Mg = ~24 + Cl = ~35 + Cl = ~35 = 94
2. Use correct conversion factor:
1.25 mol MgCl2 X 94g MgCl2
1mol MgCl2
3. Multiply across and cancel like units!
ANSWER = ~ 118g MgCl2