1. Chemical Equations

2. Numbers and Formulas What’s the Difference? H2 2H See Diatomics 2H2
2H2O
See Diatomics

3. Your Turn #1: Draw what each of the following look like:
3BH2Cl
How many H’s
How many B’s, H, Cl

4. Na + Cl2  NaCl “Reacts with” --or-- “and” “To yield” --or-- “produce”
Reactants
Product
“Sodium reacts with chlorine to produce sodium chloride”

5. Including States in Equations
(s), (l), (g), mean solid, liquid, and gas
(aq) means aqueous _______________
() means precipitate or solid
(↑) means gas is produced
KCl(aq) + AgNO3(aq)  KNO3(aq) + AgCl(s)
(dissolved in water)

6. Symbols Above the Arrow:Pt
CO(g) + O2(g)
CO2(g)
Any other compound or element means a catalyst
Catalyst - a substance that aids in the process of a chemical reaction without itself being used up or changed.
Catalysts help to speed up reactions
Enzymes are examples of catalysts within the body

7. Symbols Above the Arrow:
HgO(s)
2Hg(l) + O2(g)
Means that heat is added
“ “ is Greek letter Delta, which is often used to represent “change in”
Literally means “change in heat”
Heat generally acts like a catalyst to help many reaction go faster (more collisions)

8. Other Ways to show Energy Change
Endothermic:
Energy Is
Added/
Needed/
Required ΔH
HgO(s)
2Hg(l) + O2(g)
HgO(s) + energy
2Hg(l) + O2(g)
HgO(s) kJ
2Hg(l) + O2(g)
C3H8(g) + 5O 2(g)
4H2O(g) + 3CO 2(g) + energy
C3H8(g) + 5O 2(g)
4H2O(g) + 3CO 2(g) + 2,220kJ
Exothermic: Energy is Produced / Given Off

9. When burning
methane, is fire a
Product or a Reactant
Energy Change – FIRE ?
CH4(g) + O 2(g)
2H2O(g) + CO 2(g) + energy
In Exothermic reactions, the reaction gives off energy.
The “fire” that you see is the heat and light energy that is given off
Fire is a result of the reaction, not added to it.

10. Demo Barium hydroxide + ammonium thiocyanate
Potassium permanganate + glycerin

11. Your Turn #2: Write a formula equation for the following
Solid potassium nitrate is heated to produce gaseous oxygen and solid potassium nitrite
Ammonia gas (NH3) is reacted with oxygen in the presence of a platinum-rhodium catalyst to produce nitric acid (all acids are aqueous)

12. Your Turn: Log in to computer and open HW: Packet Pages 9-11 Stu_Lab
SH_Students
ChemCD
Balancing Equations
Balancing.pps

13. Factors Affecting Rates of Chemical _ Reactions (Bottom of Packet Page P8)
Catalysts
Concentration
The ________ the concentration, the _______ the rate of reaction
Surface Area
The _______ the exposed surface area, the ________ the rate of reaction
Temperature
The higher the temperature, the _______ the rate of the reaction because more _________ are occurring at a given time.
Agitation

14. Balancing Equations Write the word equation for the reaction
Write the formula for each substance
Make sure all compounds add up to zero
Watch out for diatomic elements
Work one element at a time and adjust the coefficients to make the same on both sides
Do NOT Touch the Subscripts!!!
Save H & O for last
Make sure cofficients are in lowest whole number ratio

15. Balancing Equations: Example #1
potassium chlorate  potassium chloride + oxygen

16. Balancing Equations: Example #2
Barium nitrate + Aluminum Aluminum nitrate + Barium

17. Balancing Equations: Your Turn
Iron + oxygen  Iron(III) oxide

18. What does it mean if an element is Diatomic ?
“Regular” Elements
Diatomic Elements
What does it mean if an element is Diatomic ?

19. Ar N2 C O2 Symbol “Regular” Elements Diatomic Elements Nitrogen Argon
Carbon
Oxygen C O2

20. What Elements are Diatomic?
Hydrogen (H2)
The
-gens
and the
-ines
are diatomic
Nitrogen (N2)
Oxygen (O2)
Fluorine (F2)
Chlorine (H2)
Bromine (Br2)
Iodine (I2)

21. Halogens
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