CH. 4 CHEMICAL REACTIONS
& SOLUTION STOICHIOMETRY
SEE UNIT 2 STUDENT TOPIC LIST
UNIT 1 EXAM ANALYSIS
Averages:
• Overall – ____%
• Scoring Information
• Question Review
LAB REPORT 101
Expectations Review
Scoring Rubric
Identifying characteristics of a quality lab report
Review comments on personal report and formulate plan of
action to improve.
AP Ch. 4 (Reactions and Soln Stoich -- Exam Objectives
I can apply the following concepts…
Electrolytes and Ions
Soln Stoichiometry (LR/XS with solutions)
Soln Stoich goes along with solubility rules
Solubility Rules!
Net Ionic Equations (NIEs), spectator ions, etc and how to write NIEs
Molarity=mol solute/L soln (what you need to calculate it)
M1V1=M2V2 “dilution equation”. Used to calculate dilutions or back calculate concentrated molarities
Titration (Redox bleach lab and what titration is and how to classify a titration rxn)
Types of Reactions:
• SD
• DD or precipitation
• Combustion
• Redox
• Decomposition
• Acid-Base (know strong acid/base lists & how to write strong/weak in NIEs)
**DO NOT WORRY ABOUT COMPLEX IONS**
Types of Reactions and how to predict reaction products and writing NIEs w DD
REDOX reactions and how to balance in acid and base (memorize rules in order!)
Oxidation state….know all rules on sheet. Do not forget diatomic elements are zero.
LEO goes GER
Copper Reactions Lab
AP Ch. 4 (Reactions and Soln Stoich) and Ch. 5 Gases Exam Objectives
NEXT…
I can apply the following concepts…
Kinetic Molecular Theory and Gases
Ideal vs. Real Gases
What conditions are ideal for gases?
PV=nRT
PV=(m/MM)RT
Know how to convert C to K
Density and gases and MW kitty cat
Graham’s Law of Effusion
Molar volume of any gas at STP= 22.4 L/mol
STP= 0°C (273 K) and 1 atm=760 mm Hg = 760 torr
Combined Gas Law P1V1 =P2V2
T1
T2
Boyles Law P1V1=P2V2
Charles’ Law V1/T1 = V2/T2
Gay Lussac’s Law P1/T1 = P2/T2
Avogadro’s Law or n is proportional to L or volume
Molar Volume of a Gas Lab
Dalton’s Law of Partial Pressures (Ptotal = P1 + P2 + P3 + P4 …..)
Mole fraction (it is really a mole decimal and no units)
Barometric pressure and manometers
Kinetic energy and as a function of temperature
**Sig Figs and Units!**
WATER, THE COMMON SOLVENT
• Water is not a linear molecule. It is bent at an angle of about
105°
• Electrons are not evenly distributed around the atoms in water.
The molecule is polar because the charges are not distributed
symmetrically.
•
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Like dissolves like. The following classes of molecules, in general,
are miscible:
• Polar and Ionic
• Polar and Polar
• Nonpolar and nonpolar
Ionic salts dissolve in water. Compounds that contain only carbon
and hydrogen are nonpolar.
Predict whether each pair of substance will mix. Explain.
• NaNO3 and H2O
• C6H14 and H2O
• I2 and C6H14
• I2 and H2O
DISSOCIATION OF IONIC
SALTS IN WATER
Model:
NaI(s)
Ba(OH)2(s)
Practice:
CaCl2(s)
Fe(NO3)3(s)
ELECTROLYTES
Solute
dissolves into the solvent
(if same phase as solvent it is the one in lesser amount)
Solvent
dissolves the solute
(if same phase as solvent it is the one in greater amount)
Aqueous Solution
water is the solvent
Strong Electrolyte
high conductivity
total dissociation
examples: strong acids (HCl); salts (NaCl); strong bases (Ba(OH)2)
Weak Electrolyte
low conductivity
partial dissociation
examples: weak organic acids (acetic acid); weak bases (NH3)
Non Electrolyte
no conductivity
close to zero dissociation
examples: sugar, AgCl
COMPOSITION OF SOLUTIONS
Molarity (M)
moles of solute per liter of solution.
M = (moles of solute) / (liter of solution)
*Watch Units!*
EXAMPLE A
Calculate the molarity of a solution prepared
by dissolving 11.85 g of solid KMnO4 in
enough water to make 750.mL of solution.
Solution Steps:
1. Convert from grams to moles.
2. Divide moles by volume (in Liters!) to get molarity.
**GUESS METHOD!**
EXAMPLE B
Calculate the mass of NaCl needed to
prepare 175 mL of a 0.500M NaCl solution.
EXAMPLE C
How many mL of solution are necessary if
we are to have a 2.48 M NaOH solution that
contains 31.52 g of the dissolved solid?
EXAMPLE D
Calculate the molarity of all the ions in each of the
following solutions.
**Hint: always write out the dissociation equation**
a. 0.25 M Ca(OCl2)
b. 2 M CrCl3
EXAMPLE E
Determine the molarity of Cl- ion in a solution
prepared by dissolving 9.82 g of CuCl2 in enough
water to make 600. mL of solution.
DILUTIONS
An important part of chemistry is to be able to prepare dilute
solutions from more concentrated “stock” solutions.
Remember—
“Moles of solute after dilution = moles of solute before dilution”
Thus—
M1V1 = M2V2
EXAMPLE F
What volume of 12 M hydrochloric acid must
be used to prepare 600 mL of a 0.30 M HCl
solution?
EXAMPLE G
What volume of 9.0 M sodium hydroxide
must be used to prepare 1.2 L of a 1.0 M
NaOH solution?
FOR NEXT TIME…
Lab Revisions Due: ______________
Continue…Ch. 4 Reading pages 127-162
Practice Problems (Sections 4.1-4.3)
Beginning on page 171: # 21, 22, 23, 24, 25, 27, 28, 29,
and 30
**Also noted on Unit 2 Review Packet**