Final Review Honors Chemistry
Mar 30, 2015
Final Review
Honors Chemistry
Classes of matter
Physical Changes
- are those in which the identifying properties of a substance are unchanged
- Ex. : change of phase breaking, cutting
dissolving
Chemical Changes
- are those in which different substances are formed
- Ex.: burning rusting decaying or spoiling acid reacting with metal
subatomic particles
Atomic no.=# protons
#protons=#electrons
Mass no.=#protons +
# neutrons
Electron configuration notation
Helium has 2 electrons, so its electron
configuration would be 1s2
Li 1s22s1
N 1s22s22p3
Ne 1s22s22p6
Na 1s22s22p63s1 or [Ne]3s1
Principal quantum number
sublevel
No. of electrons
Every orbital can hold two electrons.
“d” orbitals
Predicting electron configurations from the
periodic table.
Ways to represent titanium
1s2 2s2 2p6 3s2 3p6 4s2 3d2 electron configuration
E E E E E E E E E E h h __ __ __
1s 2s 2p 3s 3p 4s 3d Ti: 22 2 8 10 2
How would calcium and chlorine combine?
Ca Cl Cl
CaCl2
Write the formulas- always put the cation first
K+ and N3-
K3N
Ca2+ and N3-
Ca3N2
Ba2+ and NO3-
Ba(NO3)2
Criss-cross rule of thumb
Naming molecular compounds
Use prefixes 1 mono-
2 di-3 tri-4 tetra-5 penta-6 hexa-7 hepta-8 octa-9 nona-10 deca-
My favorite “no”
nameNH4CO3
Write the formula forCalcium chloride
Nitrogen tetrahydrogen carbon trioxide
CaCl
Ionic or covalent?
NaBr CH4
Fe2O3
CO2
CaO NH4Cl SiCl4
Name
ionic
covalent
ionic
covalent
ionic
ionic
covalent
Sodium bromide
Carbon tetrahydride
Iron oxide
Carbon dioxide
Calcium oxide
Ammonium chloride
Silicon tetrachloride
Types of reactions
Decomposition: AB g A + BSynthesis (or “combination”): A + B g
ABSingle Replacement (or
“displacement”): A + BC g B + AC Double Replacement (or
“displacement”): AB + CD g AD + CBCombustion: CH4 + 2O2 g CO2 + 2H2O
Balance and classify Al + Cl2 AlCl3
2Al + 3Cl2 2AlCl3
Zn + HCl ZnCl2 + H2
Zn + 2HCl ZnCl2 + H2
Mg(ClO3)2 MgCl2 + O2
Mg(ClO3)2 MgCl2 + 3O2
C4H8 + O2 CO2 + H2O
C4H8 + 6O2 4CO2 + 4H2O
Writing Balanced equations
(NH4)2CO3 + Ba(NO3)2 g NH4+
CO32- Ba2+ NO3
-
NH4+
NO3-
+
2NH4NO3BaCO3i
Double displacement
Net ionic: CO32- + Ba2+ gBaCO3i
Chemical reactions involve energy
Endothermic reactions absorb energyex.: photosynthesis
CoCO3 + 81.6 kJ g CoO + CO2 Exothermic reactions give off energy
ex.: burning of woodC(s) + O2(g) g CO2(g) + 393.5 kJ
Reaction Tendencies
Reactions occur spontaneously when a lower energy state is achieved.In exothermic reactions, the products have less energy than the reactants.
Reactions occur spontaneously when a state of less order is achieved.Entropy is the disorder in a system.
Molecular mass (molar mass)
NaCl23.0 + 35.5 = 58.5
Ba(NO3)2
137.3 + 2(14.0) + 6(16.0) = 261.3
CuSO4∙5H2O
63.5 + 32.0 + 4(16.0) + 10(1.0) + 5(16.0) = 249.5
Solution concentrations
Percentage by weight. g solute x 100%
g solution g solute x
100% g solute + g solvent
Molality moles solute = m kg solvent Molarity M = moles solute L solution
M∙V = moles Dilutions TitrationsM1V1 = M2V2 MaVa = MbVb
If I wanted 100ml of 2.0M HCl, how much 6.0M HCl would I need?
6.0M x ?ml = 2.0M x 100ml 33.3ml
Conversion Factors
Molar mass atomic mass in g = 1 mole Volume of gas At STP, 1 mole gas = 22.4L
Mole-mole ratio coefficients from balanced equation
Avogadro’s number 6.02 x 1023 molecules = 1 mole
How many molecules are in 2.0 moles of H2O?
2.0 moles x 6.02x1023molecules
1 mole
What volume would 2.5 moles of H2 gas have at STP?
2.5 moles x 22.4L = 56L 1 mole
Stoichiometry
g g mole g mole
L(gas)
molecules
Molar mass
Molar mass
22.4L=1 mol6.02 x 1023 molecules = 1 mole
Multiple conversion factors may be needed
How many grams of CO2 are formed from 18.5 grams of O2 in the following reaction?
2C2H6 + 7O2 g 4CO2 + 6H2O
18.5 g O2 x 1mole O2 x 4 mole CO2 x 44 g CO2
32 g O2 7 mole O2 1mole CO214.5g
How many liters of CO2 are formed from 18.5 grams of O2 in the following reaction?
2C2H6(g) + 7O2(g) g 4CO2(g) + 6H2O(g)
18.5 g O2 x 1mole O2 x 4 mole CO2 x 22.4 liters
32 g O2 7 mole O2 1mole CO2
7.40L
Limiting Reactants In a chemical reaction, the reactant
which gets used up first limits how much product is formed.
i.e. If I had 5 moles of Al and 4 moles of Cl2, which reactant is limiting?
2Al + 3Cl2 g 2AlCl35 mole Al x 3 mole Cl2 = 7.5 mole Cl2 2 mole AlCl2 is limiting and Al is excess.
Have
Need
% yield = actual x 100% theoretical
If 5.50g of hydrogen reacts with nitrogen to form 20.4g of ammonia, what is the percent yield?
N2(g) + 3H2(g) g 2NH3(g)Actual = 20.4gTheoretical = 5.50g H2 x 1 mol H2 x 2mol NH3 x
17.0g NH3 2.0g H2 3mol H2 1mol
NH3
The amount of heat gained or lost depends on the amount of
reactants used.2Na2O2 + 2H2O g 4NaOH + O2 +
215.76 kJ
How much heat is released by the reaction of 5.0 moles of Na2O2?
5.0 moles Na2O2 x 215.76 kJ = 539.4 kJ 2 mole Na2O2
Q = m∙c∙∆T
Heat = mass ∙ specific heat∙ change
gained or lost in temp
Ex: How much heat is lost when a solid aluminum ingot with a mass of 411g cools from 660.0˚C to 25˚C? cAl =
0.903J/g˚C ∆T = 660.0 – 25 = 635˚CQ = (411g)(0.903J/g˚C)
(635˚C)=236,000 J
Charles Law V1 = V2 P constant
T1 T2
Boyles Law P1V1 = P2V2 T constant
Combined P1V1 = P2V2
T1 T2
Gay-Lussac’s Law P1 = P2 V constant
T1 T2
If temperature increases, volume ______.
increases. Always change Celsius to Kelvin
degrees.Ex.: If a gas expands from 125ml to
850ml, its original temperature of 15◦C must have changed to what?
15◦C=288K 288K x 850ml = 1958.4K 125ml
52.5 ml of a gas is collected over water at 20˚C and 100.0 kPa. What is the pressure of the dry gas?
100.0 kPa = Pgas + Pwater
Pwater at 20˚C = 2.3 kPa100.0 kPa – 2.3 kPa = 97.7 kPaWhat would be the volume of this gas
at STP? P1= 97.7 kPa P2=101.325kPaV1= 52.5 ml V2= ?T1= 20˚C=293 K T2=273 K
P1V1 = P2V2
T1 T2
52.5ml∙97.7 kPa = 101.325kPa ∙ V2
293K 273K
V2= 47.2ml
PV=nRT
P=Pressure V=volume n=moles R= gas constant = 0.0821 L∙atm mol∙K 8.31L·kPa mol∙K or 62.4 L∙torr mol∙K T= temperature (K)
When given three of the four variables, we can find the
fourth. A gas has a volume of 2.20L at 25◦C.
If there are .085 moles of the gas, under what pressure must the gas be held?
P = nRT V P = (.085mole)(0.0821 L∙atm)
(298K) 2.20L mol∙K
Compute the relative rate of diffusion of helium and argon.
16.3104
40
He
Ar
Ar
He
m
m
v
v
My favorite “no”
What volume of 2.0M HCl do you need to get .5 moles of HCl?
2.0M x 22.4L = 44.8L mole
[H+] = 10-pH [OH-] = 10-pOH
pH + pOH = 14.0
Sample problem:A 0.01 M sample of NaOH completely
ionizes. What is its pH, pOH, [H+], and [OH-] ?
[OH-] = 0.01 mole/L = 10-2 pOH = 2pH = 14 – pOH = 12 [H+] = 10-12
pH pOH [H3O+] [OH-]
6 8 10-6 10-8
1 13 10-1 10-13
Find the pH of a solution with [H3O+] of 6.59 x 10-10M.
pH = -log(6.59 x 10-10)pH = -(log 6.59 + log 10-10) = 9.18Find the [H3O+] of a solution with a pH
of 9.18.Antilog(-9.18)
Equilibrium Shifts
Concentration Removing products shifts equilibrium
right Adding a product shifts equilibrium
left
Pressure Increasing pressure on gases shifts
equilibrium toward side with fewer number of moles
Redox reactions
Identify the reducing and oxidizing agents.
Mg(s) + Cu(NO3)2(aq) Mg(NO3)2(aq) + Cu(s)
0 +2 +5 -2 +2 +5 -2 0
Mg is oxidized and is the reducing agentCu is reduced and is the oxidizing agent
Types of radiation
Alpha (α) low penetrating power
Beta (β) moderate penetrating power
Gamma (γ) high penetrating power
He42
e01
Transmutations
Complete the following nuclear equation.
KrRb 8336
8337 ?
e01
Half LifeIf you start with 2.97 x 1022 atoms of
,How many atoms will remain after 62
minutes? The half life of is 15.49 minutes.
62 = 4 half lives15.5
2.97 x 1022 atoms (½)4 = 1.86 x 1021 atoms
Mo9142
Mo9142
Fission- breaking apart of a nucleus
Can cause a chain reaction
Fusion- happens on the sun
TITRATION, NEUTRALIZATION…