Chemistry Final Exam
Test Yourself
Definitions
When a stress is added to a chemical
reaction at equilibrium, the reaction shifts
so as to relieve the stress
(Le Chatelier’s Principle)
This lowers the activation energy of a
reaction
(Catalyst)
The actual steps that occur in a chemical
reaction
(Reaction Mechanism)
A chemical reaction is this if it occurs
naturally
(Spontaneous)
A reaction which takes in heat energy;
product has more potential energy (+∆H)
(Endothermic)
A reaction which gives off heat energy;
product has less potential energy (-∆H)
(Exothermic)
The kinetic energy necessary for a chemical
reaction to occur
(Activation Energy)
When the maximum amount of solute has
dissolved in a solvent at a specific
temperature; increases with temperature
(Saturated Solution)
A measure of the energy of disorder in a
substance
(Entropy)
A measure of the potential energy
associated with a substance
(Enthalpy)
A chemical reaction is at this when the
concentrations of reactants and products
remain constant. (Forward reaction rate
= Reverse reaction rate.)
(Equilibrium)
Branch of chemistry that can be used to
determine how fast a reaction occurs
(Kinetics)
The branch of chemistry that can be used to
determine whether or not a reaction is
spontaneous
(Thermodynamics)
The pressure that sits over any liquid
(Vapor pressure)
The total pressure is equal to the sum of the
individual pressures
(Dalton’s Law of Partial Pressures)
Moles of solute per kilograms of solvent
(Molality)
A measure of the maximum amount of
solute dissolved in a solvent at a given
temperature
(Solubility)
A homogenous mixture
(Solution)
20% there!
A substance that is dissolved
(Solute)
A substance that dissolves another
(Solvent)
Disorder is increasing in the universe
(2nd Law of Thermodynamics)
A substance that changes color in an acidic
or basic environment
(Indicator)
A molecule that accepts an H+ ion
(Base)
A molecule that donates an H+ ion
(Acid)
Used to indicate concentration (moles/liter)
(Molarity)
A molecule is this when the atoms in it share
electrons. Composed of non-metals
(Covalent)
A compound is this when the atoms in it give
or take electrons. Composed of at least
one non-metal and one metal
(Ionic)
Short Answer
What are the 4 factors that affect the rate of
a reaction?
(Concentration, surface area, temperature,
and adding a catalyst)
As the number of ions increases in a
solution, the ____________ goes down
(Freezing point)
As the number of ions increases in a
solution, the ____________ goes up
(Boiling point)
If the equilibrium constant (K) is much less
than one, are there more products or
reactants at equilibrium?
(reactants)
If the Ka for an acid is much greater than
one, is it a strong or weak acid?
(strong)
Which gas law includes pressure, volume,
temperature, and the # of moles?
(Ideal Gas Law – PV = nRT)
Whose law states that as the temperature of
a gas increases, the volume also
increases?
(Charles’)
Whose law states that as the pressure of a
gas increases, the volume decreases?
(Boyles)
What are 4 units of pressure?
(atm, torr, mm Hg, kPa)
State the geometrical shape and whether
the following is purely covalent or polar
covalent: CCl4
(Tetrahedral, purely covalent)
If the central atom in a molecule pulls
unevenly on the surrounding electrons,
what type of molecule is it?
(polar covalent)
What must be negative for a reaction to be
spontaneous?
(∆G)
What theory states that electron pairs in a
molecule are as far apart from one
another as possible?
(VSEPR – Valence Shell Electron Pair
Repulsion)
The change in enthalpy (H) is negative for
what type of reaction?
(Exothermic)
Which of the following substances contains
the greatest amount of disorder (S)?
A. 1.0 mole of CO2 (s)
B. 1.0 mole of CO2 (l)
C. 1.0 mole of CO2(g)
D. 0.5 mole of CO2(s)
(C)
Which of the following pH values is
indicative of a strong acid?
A. pH -- 1.0
B. pH -- 13.0
C. pH -- 7.0
D. pH -- 6.9
(A)
An ____________ reaction that ________
entropy will always be spontaneous.
(exothermic; increases)
Which is the acid and which is the base in
the following:
H2CO3 + H2O → HCO3- + H3O+?
(acid – H2CO3; base – H2O)
2NO + I2 → 2NOI This reaction is 2nd order
with regard to NO and 1st order with regard to I2.
What is the rate equation?
(R= k[NO]2[I2] )
For the following reaction, N2 (g) + O2 (g) ↔ 2NO
(g), the equilibrium constant at a particular
temperature is 0.050. The concentrations of
each substance are the following: [N2] = 0.5 M,
[O2] = 1.7 M, [NO] = 0.010 M. Which way will
the reaction shift so as to achieve equilibrium?
(Q = 1 x 10-4 Reaction will shift to the right)
Which arrow represents the activation energy of the catalyzed
reaction?
(6)
Which arrow represents the heat of reaction (∆H)?
(2)
Which arrow represents the activation energy for the uncatalyzed
reaction?
(1)
Is the forward reaction exo- or endothermic? Is ∆H neg. or positive?
(exothermic; ∆H neg)
More than half-way!
2 SO2 (g) + O2 (g) ↔ 2 SO3 (g) + energy
Which way would increasing the temp shift this
reaction at equilibrium?
(to the left)
Which way would decreasing the [SO3] shift this
reaction at equilibrium?
(to the right)
Increasing the pressure?
(to the right)
A ______ ______ is used in galvanic cells to
maintain charge balances between the 2
half-cells.
(salt bridge)
What is the electrolyte in lead-acid (car)
batteries?
(sulfuric acid)
What is the oxidation number of Chromium in
CrO42-?
(+6)
Zn + 2MnO2 + 2NH4+ + 2Cl- →
Zn2+ + Mn2O3 + 2NH3 +2Cl- + H2O
What is the reducing agent? Oxidizing agent?
(Zn – reducing agent; MnO2 – oxidizing agent)
What is the oxidation number of carbon in
H2C2O4?
(+3)
What is the formula for carbon disulfide?
(CS2)
Fe(s) + Ni2+(aq) → Fe2+(aq) + Ni(s)
What reaction is taking place at the anode?
(Fe(s) → Fe2+ (aq) + 2e- )
What reaction is taking place at the cathode?
(Ni2+(aq) + 2e- → Ni(s)
Where is the nitrate ion going?
(to the anode)
Where is the K+ ion going?
(to the cathode)
What is the formula for calcium carbonate?
(CaCO3)
What is the formula for iron III oxide?
(Fe2O3 )
What is the formula for dinitrogen
monoxide?
(N2O)
Which of the following conducts electricity? CO2,
Ne, Ag, CCl4
(Ag)
What is the molecular geometry of CO2?
(linear)
What type of bond exists in H2?
(purely covalent)
Acids taste ___, donate__ ions.
sour
H+
Bases taste__, accept __ions, donate __ions, denature___.
bitter
H+
OHprotein
In a neutral solution, [H+] is ___[OH-]. In an acidic
solution, [H+] ____ [OH-]. In a basic solution, [H+]
is ____ [OH-].
(equal to; greater than; less than)
What is the concentration of 20.0 g of NH3
dissolved in 130 mL of water?
(9.0 M)
A(n) ____ in temperature will help a solute
that dissolves endothermically dissolve.
(increase)
A solution is a _______ mixture.
(homogeneous)
If a saturated solution at 80oC is cooled to
25oC, what will happen?
(a precipitate will form)
When you drink from a straw, you _____ the
pressure inside the straw allowing the
______ ______ to push the liquid up.
(decrease; atmospheric pressure)
When you heat up a gas in a closed
container, what happens?
(temperature increased; pressure increased)
1 atm = _____ mm Hg
(760)
Walking up a hill is an example of a
________ process; rolling a rock down a
hill is an example of a _______ process.
(nonspontaneous; spontaneous)
List in order of least entropy to most entropy:
1 mol H2O(l), 1 mol H2O(g), 1 mol H2O(s)
(solid – liquid – gas)
An endothermic reaction feels ___ to the
touch. An exothermic reaction feels ___ to
the touch.
(cold; hot)
What is the catalyst in the following:?
2NO(g) + O2(g)→ 2NO2(g)
2NO2(g) + SO2 → 2SO3(g) + 2NO(g)
(NO(g))
Predict what will happen to the rate of a reaction
when you double the concentration of a reactant
whose “x” has the following values: 0, 1, 2
(no change; double; quadruple)
A homogeneous catalyst is in the same
_____ as one of the reactants;
heterogeneous, different ______ than any
of the reactants.
(phase; phase)
Most household spills are ____; most
cleaners are _____.
(acidic; basic)
You have a stock solution of 18 M H2SO4
and would like to make 500.0 mL of 3.0M
acid. How would you do it?
(take 417 (420 SF) mL of water and add 83
mL of 18 M H2SO4)
What are the six strong acids? Everything
else is _________!
(HBr, HI, HCl, H2SO4, HClO4, HNO3; weak)
In a gas mixture of H2, He and Ar, the total
pressure is 90.3 kPa. The partial pressure of Ar
is 40.7 kPa, and the partial pressure of He is 5.1
kPa. What is the partial pressure of H2?
(44.5 kPa)
The_______ ____ is when the vapor pressure of a
liquid is equal to atmospheric pressure.
(boiling point)
A gas has a volume of 20.0 L at 100.oC and
500. mm Hg. What is its new volume at
60.oC and 700. mm Hg?
(13 L)
Gasoline and water do not mix because
gasoline is _____ and water is ______.
(purely covalent; polar)
2 SO2 (g) + O2 (g) ↔ 2 SO3 (g)
What is the equilibrium constant for the above
reaction?
(K = [SO3]2 (click one more time)
[SO2]2[O2]
What is always true when a reaction is at
equilibrium?
[rate of forward rxn = rate of reverse rxn – NOT
that the concentrations of the products and
reactant are ALWAYS equal (only when K = 1)]
Under which of the following conditions
would you expect gases to behave
ideally?
A. T = 100 K, P = 1.0 atm
B. T = 300 K, P = 1.9 atm
C. T = 150 K, P = 1.0 atm
D. T = 273 K, P = 0.5 atm
(D)
Almost there!!!
When iron oxidizes, what is it called?
(Oxidation, rusting, corrosion)
If a reaction gets hot, it is an ________ rxn
and _________ heat to/from the
surroundings.
(exothermic; releases… to)
A strong acid or base dissociates ___________
into its constituent ions in an aqueous solution.
(Completely!)
CONGRATULATIONS!!! YOU’RE DONE!!!!!!