1. Simplest (Empirical) Formula
Simplest integer ratio of the atoms in a compound
Assume 100 g of compound, %element is then g element in sample
g element x 1 mol element = mol element
g element
CHCl g C x 1 mol C = mol C
g C
Determine simplest integer mole ratio

2. EXAMPLE: Phosphorus burns in air to produce a white compound that is 43.7% P and 56.3% O by mass. What is the empirical formula of the compound?
Assume 100 g of compound
Relative Number of Atoms
Multiply
by Integer
mass
43.7g P
56.3g O
(mass/atomic mass)
Divide by Smaller
43.7/ = 1.41
56.3/ = 3.52
2  1.00  2
2  2.50  5
1.41/1.41 = 1.00
3.52/1.41 = 2.50
.25, .33, .5, .67, .75
¼, ⅓, ½, ⅔, ¾
1:1.25 = 4:5
Empirical Formula  P2O5

3. Molecular Formula
The exact proportions of the elements that are contained in a molecule
An integer multiple (X) of the empirical formula
MF = X  EF

4. Molecular Formula from Simplest Formula
empirical formula mass  FM
sum of the atomic weights represented by the empirical formula
molar mass = MM = X  FM

5. Molecular Formula from Simplest Formula
first, knowing MM and FM
X = MM/FM
then
MF = X  EF

6. EXAMPLE: Our phosphorus compound has a molar mass of ~285
EXAMPLE: Our phosphorus compound has a molar mass of ~285. What is the molecular formula?
FM = 2 x x = MM
X = = = 2 FM
thus MF = 2  EF
P4O10

7. The empirical formula of a substance is found to be CH3O and its molecular weight is found to be roughly 61 g/mol. What is the true molecular weight of the substance?
30.5 g/mol
31.0 g/mol
61.0 g/mol
62.0 g/mol
124.0 g/mol
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8. Biological Periodic Table

9. Carbohydrates Cx(H2O)y
Glucose C6H12O6

10. Sucrose
Glucose + Fructose  Sucrose + Water

11. Tristearin - Glycerol - Stearic Acid
3H2O+ +3

12. Quantities of Reactants and Products
Chapter 4
Quantities of Reactants
and Products

13. Balanced Chemical Equation
Representation of a chemical reaction which uses stoichiometric coefficients (prefix numbers) to represent the relative amounts of reactants and products
2 H2 (g) + O2 (g)  2 H2O (l)
Molecule to Molecule or Mole to Mole

14. balanced chemical equation
EXAMPLE How much H2O, in moles results from burning an excess of H2 in 3.3 moles of O2?
2 H2 + O2  2 H2O
(3.3 mol O2) (2 mol H2O)
#mol H2O = = 6.6 mol H2O
(1 mol O2)
Mole ratio from
balanced chemical equation

15. Reaction of H2 and Cl2 or H2 (g) + Cl2 (g)  2 HCl (g)
one to one gives two or
four to four gives eight

16. Types of Reactions synthesis or combination reactions
decomposition reactions
displacement reactions
exchange reactions

17. Types of Chemical Reactions

18. Synthesis or Combination Reactions
Formation of a compound from simpler compounds or elements.

19. Combination Reaction

20. Decomposition Reactions
Separation into constituents by chemical reaction.

21. Dynamite

22. Electrolysis

23. Displacement Reactions
Reaction of a compound with a more reactive element to produce a new compound and release a less reactive element

24. Displacement Reactions

25. Exchange Reactions
Reaction where ion partners are exchanged

26. Pb(NO3)2 (aq) + K2CrO4 (aq)  PbCrO4 (s) + 2 KNO3 (aq)

27. When Zn(s) is placed in aqueous HCl, hydrogen gas is evolved and zinc chloride solution is obtained. Predict the reaction type.
Combination
Combustion
Decomposition
Displacement (single displacement)
Exchange (double displacement)
Instructor comment:
The answers include the possible reaction types and any answer may be selected if the student is clueless. This question requires cumulative skills including writing correct formulas and identifying reaction type. The student must carefully examine the reactants and products and determine the net change during the reaction. The instructor can review these concepts when discussing the solution to the problem and emphasize the need to retain information by drill and practice outside class and reinforcement in class.
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28. Writing and Balancing Chemical Equations
Determine the type of reaction and formulae of the products
Write an unbalanced equation with the correct reactants and products
Balance the equation by the use of prefixes (coefficients) to balance the number of each type of atom on the reactant and product sides of the equation.

29. Example
Iron is produced by the reduction of iron(III) oxide with CO which forms CO2
iron(III) oxide + carbon monoxide  iron + carbon dioxide
Fe2O3 + CO  Fe + CO2
Fe2O3 + CO  2 Fe + CO2
Fe2O CO  2 Fe CO2

30. When aluminum reacts with sulfuric acid to yield aluminum sulfate and hydrogen what is the SUM of the coefficients in the balanced equation? 4 6 7 8 9
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