Download presentation
Presentation is loading. Please wait.
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 130 10
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. 130 10
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 9 130 10
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.