Post on 18-Jan-2016
transcript
CHAPTER ONEThe Foundations of Chemistry
RECALL!!!
Elements: Can not be broken down by chemical reactions
Pure Substances Compounds: Can be broken down
ONLY by chemical reactions
Matter Homogeneous: Constant
composition throughout
Mixtures Can be separated by Heterogeneous: Variable
composition physical processesthroughout 2
3
States of Matter
4
A
B C
D
E
5
States of Matter
6
Chemical and Physical Properties Chemical Properties - chemical
changes rusting or oxidation chemical reactions
Physical Properties - physical changes changes of state density, color, solubility
7
Question 1. Classify as mixtures (homogeneous or heterogeneous), compounds (ionic or molecular), or elements (monoatomic or molecular).Classification
C2H5OH
Cl2Cu
bronze
5% AgNO3 solution
C6H12O6
PbCl2 precipitate
Zn
Ba3(PO4)2
0.5 M CaCl2
8
Mixtures, Substances, Compounds, and Elements
Separation of Mixtures Distillation: It separates 2 or more liquids with different boiling points. For example: ethanol (bp: 78°C) and water (bp: 100°C) Fractional crystallization: It separates 2 or more solids (by means of precipitation) with different solubility. Filtration: It separates an insoluble solid from a liquid. The solid must be insoluble in the liquid. For example: sand-water, silver chloride-water. Chromatography: It separates substances that are soluble in a solvent by means of IMF. Evaporation: It separates a soluble solute from its solvent by evaporating the solvent. For example: NaCl-H2O Liquid – liquid separation: It separates 2 immiscible liquids using a separatory funnel. For example: oil-water
10
Distillation
Separates homogeneous mixture on the basis of differences in boiling point.
Ethanol-water
11
FiltrationSeparates insoluble solid substances from liquids and solutions.
12
Chromatography:Separates substances on the basis of differences in solubility in a solvent and IMF.
13
Measurements in Chemistry
Quantity UnitSymbol
length meter m
mass kilogram kg
time second s current ampere A temperature Kelvin K amt. substance mole
mol
14
Measurements in ChemistryMetric PrefixesName Symbol Multiplier
mega M 106 kilo k 103 deci d 10-1 centi c 10-2 milli m 10-3 micro μ 10-6 nano n 10-9 pico p 10-12 femto f 10-15
15
Units of Measurement
Common Conversion Factors Length
2.54 cm = 1 inch Volume
1 liter = 1.06 qt Mass
1 lb = 454 g
16
Volume The most commonly
used metric units for volume are the liter (L) and the milliliter (mL). 1 dm = 10 cm 1 dm3 = 1000 cm3
1 L = 1000 mLtherefore 1 mL = 1 cm3
17
Uncertainty in Measurements
Different measuring devices have different uses and different degrees of accuracy.
18
Relationships of the Temperature Scales
Kelvin and Celsius RelationshipK = °C + 273.15
Fahrenheit and Celsius Relationship°F = 1.8 * °C + 32
19
Use of Numbers
Exact numbers 1 dozen = 12 things for example
Accuracy how closely measured values agree with the correct
value. The experimental value is 23.5148g, the actual value is 23.5150g. These 2 masses are accurate.
Precision how closely individual measurements agree with
each other. The value of the mass of the same beaker in 3 trials are: 23.5148g, 23.5152g, 23.5145g. These values are precise.
20
Percent error Percent error = accepted – experimental x
100 accepted
From previous example:% error = 23.5150 – 23.5148 x 100 = 0.0009 % 23.5150
21
Use of Numbers
Significant Figures – Rules All non-zero digits are significant. Leading zeroes are never significant
0.000357 has three significant figures Imbedded zeroes are always significant.
2.0059 has five sig fig Trailing zeroes are only significant after the
decimal point. 1300 g has 2 sig fig 13.00 g has 4 sig fig
Use scientific notation to remove doubt1.300 x 103 has 4 significant figures
22
Use of Numbers
Multiplication & Division rule Easier of the two rulesProduct has the smallest number of
significant figures of multipliers
5.22 tooff round
21766.5
31.2x
224.4
3.9 tooff round
89648.3
41.x
2783.2
23
Use of Numbers
Addition & Subtraction ruleMore subtle than the multiplication ruleAnswer contains smallest decimal place of the
addends.
6.95 tooff round
9463.6
20.2
423.1
3692.3
6.671 tooff round
6707.6
312.2
7793.8
24
Use of Numbers
On a multi-step question, solve all mathematical steps and ONLY round off the final answer.
25
Using Factor Label Method
Example: A concentrated hydrochloric acid solution is 36.31% HCl by mass. The density of the solution is 1.185g/mL. What mass of pure HCl is contained in 175 mL of this solution?
solution g 100.00
OH g 63.69or
solution g 100.00
HCl g 36.31or
OH g 63.69
HCl g 36.31
Problem thisfrom Factors UnitPossible Some
2
2
mL
g 1.185density
HCl g 75.3
soln g 100.00
HCl g 36.31
soln mL 1
soln g 1.185soln mL 175
26
Problem 2. Calculate the volume of solution required to prepare 0.025 M solution of Na2SO4 if only 0.050g of the salt is available. Known:
Molar mass of Na2SO4 is 142.1 g/mol. 0.025 M means 0.025 mol/L.
Problem 3. Calculate the density of a cobalt(II) chloride solution with a molarity of 3.57 M and a percent mass by mass of 17.46%.
27
Review Nomenclature Compounds: Ionic Covalent Hydrates Acids
Ionic compounds
Metal + Nonmetal
Groups IA, IIA,Al, Ag, Zn, Cd
Only one oxidation number
Name of the metaldoes not change:lithium, calcium
Other metals
More than oneoxidation number
Roman numerals to specify charge:iron(II), iron(III),tin(II), tin(IV)
Stem of element + ideoxide, sulfide, chloride
BinaryTwo elements Ternary
More than two elements
Ionic compounds
Metal or NH4+ + Polyatomic anion
Groups IA, IIA,Al, Ag, Zn, Cd
Only one oxidation number
Name of the metaldoes not change:lithium, calcium
Other metals
More than oneoxidation number
Roman numerals to specify charge:iron(II), iron(III),tin(II), tin(IV)
BinaryTwo elements
Ternary More than two elements
Binary Molecular Compounds
non metal + stem of second non metal
ending ide
32
Formula-to-Name Acids
Acids are molecular compounds that often behave like they are made of ions.
All names have acid at end. Binary Acids = Hydro- prefix + stem of
the name of the nonmetal + -ic suffix. Oxyacids:
If polyatomic ion ends in –ate = Name of polyatomic ion with –ic suffix.
If polyatomic ion ends in –ite = Name of polyatomic ion with –ous suffix.
Hydrates Ionic compounds that crystallize with
water occluded in their crystal structure.
NaCO3 ·10H2O
BaCl2 · 2H2O
Co(NO3) 2 · 6H20