1. Posters Signs of a chemical reaction Chemical vs. Physical reaction
Symbols used in chemical reactions
Synthesis
Decomposition
Single diplacement
Double displacement
Combustion

2. Journal Entry
How were these rocks formed?

3. Signs of a chemical reaction
Production of….
Heat
Light
Gas
Precipitate (solid formed from two liquids)
Color change

4. The 5 Types of Reactions
We classify reactions into 5 categories so that we may more easily predict the products.
NEXT

5. A + B  AB  + Synthesis Definition
Synthesis reaction – 2 substances are combined to form a single product
Combination reactions may also be called composition or synthesis reactions.
A + B  AB  +
MENU

6. Synthesis Examples 2Mg + O2  2MgO
Magnesium and oxygen combine to form magnesium oxide.
2H2 + O2  2H2O
Hydrogen and oxygen combine to form dihydrogen monoxide (water)
MENU

7. Synthesis Demonstration
Zinc + Sulfur  Zinc Sulfide
Zn + S  ZnS
Observations:

8. Decomposition Definition
Decomposition reaction – A single compound is broken down into 2 or more products.
AB  A + B + 
MENU

9. Decomposition Examples
2NaCl(s)  2Na(s) + Cl2(g)
Sodium chloride (table salt) decomposes into sodium and chlorine gas.
CaCO3  CaO + CO2
Limestone (CaCO3 ) decomposes into lime (CaO) and carbon dioxide.
MENU

10. Water decomposing into hydrogen gas and oxygen gas.
Decomposition
2 H2O  2H2 + O2
Water decomposing into hydrogen gas and oxygen gas.
Decomposition of H2O2
MENU

12. Decomposition Demonstration
C12H22O H2SO4 → C H2O SO2
(balance this!)
Sugar + Sulfuric acid  Pure carbon + Water + Sulfur dioxide
Observations:

13. Decomposition Demonstration
2 NaHCO3 --> Na2CO3 + H2O + CO2
Observations:
Massinitial
Massfinal

14. Combustion Definition
Combustion reaction – Hydrogen or a hydrocarbon (H and C) burn in oxygen to produce water and carbon dioxide. Heat is given off as energy.
CxHx + O2  XH2O + XCO2
MENU

15. Combustion Examples CH4 + 2O2  2H2O + CO2
Methane burns in oxygen to produce water and carbon dioxide.
C12H22O O2  11H2O + 12CO2
A sugar molecule burns in oxygen to produce water and carbon dioxide.
MENU

16. Combustion demonstration
Ethanol + Oxygen yields Water + Carbon dioxide
C6H12O6 + O2  H2O + CO2

18. Single Replacement Definition
Single Replacement reaction – A single element takes the place of an element in a compound.
A + BC  B + AC + + 
MENU

20. Single Replacement Examples
Mg + BeO  Be + MgO
Magnesium replaces beryllium in beryllium oxide to form magnesium oxide and beryllium.
2Na + 2HCl  H2 + 2NaCl
Sodium replaces hydrogen in hydrochloric acid to yield hydrogen and sodium chloride.
MENU

21. Single Replacement Demo.
A single replacement of Zinc metal for hydrogen in hydrochloric acid.
Zn + 2HCl  H2 + ZnCl2

22. Double Replacement Definition
Double Replacement reaction – Elements in 2 compounds switch places to form 2 new compounds.
AB + CD  AD + CB + + 
MENU

24. Double Replacement Examples
MgO + BeS  MgS + BeO
Oxygen and sulfur switch places to form magnesium sulfide and beryllium oxide.
Na2S + Zn(NO3)2  2Na(NO3) + ZnS
Sulfur and nitrate switch places to form sodium nitrate and zinc sulfide.

25. Make a Venn diagram comparing….
Synthesis vs. Decomposition
Single replacement vs. double replacement

26. What type of reaction?
2 H2 + O2 -- 2H20

27. What type of reaction?
A + BX  AX + B

28. What type of reaction?
AgNO3 + CuSO4  AgSO4 + CuNO3

29. What type of reaction is this?
2 HCl (aq) + Zn (s) --> ZnCl2 (aq) + H2 (g)

30. What type of reaction?

31. Counting atoms
How many Carbons are in each of the following compounds:
CO2
C2H6
Na(CO3)2
Mg(C2O)4

32. Warm-up
Around the room there are _7__ pictures representing types of reactions. YOUR pictures.
Make a list in your notebook, 1- _7__. Try to determine what type of reaction is being represented by the drawing.

33. Definitions
Co-efficient: The number before an element/compound (allowed to change when balancing)
Ex: 2 H2
Subscript: The small number after an element/compound (NEVER allowed to change when balancing

34. Sacrificial Gummy Bear
Demonstrates:
Two types of chemical reactions
HIGHLY Exothermic energy change
Chemical energy converted into thermal, radiant and sound energy

35. Chemicals used
KClO Potassium chlorate
C12H22O11 - Sucrose

36. First reaction
KClO3 (s)  KCl (l) + O2
What type of reaction is this?

37. First reaction KClO3 (s)  KCl (l) + O2
Is this reaction balanced? (Make an RT table)

38. First reaction
KClO3 (s)  KCl (l) + O2
Balance it!

39. First reaction
2 KClO3 (s)  2 KCl (l) + 3 O2 (g)

40. First reaction
2 KClO3 (s)  2 KCl (l) + 3 O2 (g)

41. Second reaction C12H22O11 + O2 (g)  C (s) + CO2 (g) + H2O (g)
What type of reaction is this?

42. Second reaction C12H22O11 + O2 (g)  C (s) + CO2 (g) + H2O (g)
Is it balanced? (Make an R/P table)
If not, balance it! (1 min. early release if done correctly!)

43. Second reaction Balanced equation
C12H22O O2  9 C CO H2O
Balanced equation

44. Exothermic
Reactions which release energy
∆H = 5635 kJ

46. How to balance equations
1.) Create a “R/P” table
(Reactants vs. Products)
2.) Add coefficients to create equal numbers
3.) update the R/P table
4.) Change co-efficients until R = P

48. Pre-lab/practice Purpose: To generate hydrogen gas
To set norms of behavior when dealing with acid

49. Norms:

50. Locations Ring stands are on top of fume hood Clamps are in 4A
All other materials are on counter by sink 1

51. Materials Ring stand/clamp Test tube 1-2 pea-size chunks of Zn
1 bottle of HCl

52. Procedure Set up your apparatus as demonstrated
Add the Zinc to the test tube
Add approximately 2-4 cm of HCl to the test tube
Cover with a small piece of aluminum foil
Look for signs of a chemical reaction
Allow to react for 3-4 minutes

53. Test Raise your hand when time has elapsed
Use the flame test to look for signs of H2 gas

54. Clean up All test tubes must be cleaned out with Alconox
Make sure that all acid is flushed with a large amount of water
Sinks are to be totally clean

56. Homework reminder Read and take notes on pages 256-264
Answer questions 1 and 2
Due next class