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WorksheetsChem Unit VI Test
Total questions: 150
Worksheet time: 3hrs 30mins
The release of chemical potential energy produces all of the following except
cooling
heat
Chemicals in gasoline contain a large amount of potential energy because
there are many chemical bonds present
there are many compounds present in gasoline
All of the following are examples of work except
carrying a box
thinking about a problem
Heat moves from an object at lower temperature to an object at higher temperature.
True
False
The ability to monitor heat is important for an understanding of chemical processes.
True
False
In carrying out a chemical reaction, all of the following are part of the system except
the heating device to warm the reaction
the lab bench where the reaction is occurring
An example of an exothermic reaction is
burning a candle
melting ice
An example of an endothermic reaction is
making coffee
solar flares
The wood in a fireplace is part of the system.
True
False
Endothermic reactions do not need heat from the surroundings.
false
true
Cooking is an endothermic process.
true
false
A unit of heat is the ________
joule
joule/kg
If a piece of chocolate cake contains 350 Calories, that is the equivalent of
350,000 calories
35,000 calories
One calorie equals _______ joules
4.184
4.254
Which of the following will absorb the most heat from the sun in one hour?
Gulf of Mexico
Pacific Ocean
The specific heat is the amount of energy needed to raise one gram of material 1°C.
true
false
The specific heat of liquid water and of ice are the same.
true
false
Coastal climates are more moderate than climates inland.
true
false
Water is a poor coolant for engines.
true
false
When doing thermochemical calculations, the pressure is
constant
lowered
The enthalpy change is designated as
∆H
∆T
The symbol q stands for
energy
heat
Changes in enthalpy are measured as reactants are converted to products.
true
false
Heat is released or absorbed in chemical reactions
true
false
An inexpensive calorimeter can be made out of
plastic cups
foam cups
The easiest reactions to measure in an inexpensive calorimeter are
gases
liquids
Using a calorimeter, the property measured is
formation of a solid
temperature change
A lid is used to limit heat exchange between materials in the cup and surrounding air.
true
false
The dissolved materials are the surroundings.
true
false
Temperatures of solutions are measured before they are mixed.
true
false
An exothermic reaction has all of the following except
energy goes from surroundings to system
heat released is written on the product side of the reaction
A thermochemical equation includes
enthalpy change for the reaction
specific temperature change
The enthalpy change for an exothermic reaction is negative.
true
false
Physical states of reactants and products do not affect enthalpy values.
true
false
As an ice cube melts, the temperature of the ice
does not change
fluctuates
Heat of fusion is strongly influenced by
temperature
intermolecular forces
The heat of fusion for water is
6.01 kJ/mol
40.7 kJ/mol
Conversion of a gas to a liquid involves a release of energy.
true
false
To calculate the amount of energy involved in heating water from 20°C to 50°C, use the
molar heat of vaporization
specific heat of water
The process of converting ice at -20°C to steam at 140°C requires _____ steps.
six
five
The heat absorbed in melting is found using the molar heat of fusion.
true
false
The specific heat of water is used to determine the amount of energy need to convert water to steam.
true
false
A] means the number of moles of A.
true
false
In a rate, the term ∆[A] refers to a change in concentration.
true
false
An ineffective collision is one in which
no rearrangement of atoms occurs
a rearrangement of atoms occurs
Reactants form products when all of the following occur except
collisions have random orientation
collisions have enough kinetic energy
Bonds are more likely to break at higher vibrational energies
true
false
Some reactions can occur at room temperature
true
false
One of the following statements about potential energy diagrams is not true
the potential energy of products is greater than reactants in an exothermic reaction
the potential energy of products is greater than reactants in an endothermic reaction
The activated complex
indicates the energy needed for the reaction to occur
forms at the start of the reaction
The structures of most activated complexes have been thoroughly studied.
true
false
Collisions between reactants always lead to products.
true
false
Granular sugar will react more rapidly with sulfuric acid than a sugar cube will because of
greater surface area
higher pressure
A decrease in temperature results in a higher rate of collision.
true
false
Collision theory does not explain factors that influence rate of reaction.
true
false
In a reversible reaction
the reaction goes in one direction and then reverses in the other direction
check
the reaction proceeds in both directions simultaneously
Reversible reactions are indicated by
--><--
<--
-->
When a reaction takes place in both the forward and reverse directions, it is said to be reversible.
true
false
Many chemical reactions do not proceed to completion.
true
false
The forward reaction rate ________ as the reverse reaction begins
increases
decreases
Chemical equilibrium can be attained under all but one of the following conditions
removing products as the reaction proceeds
beginning with a mix of reactants and products
A phase equilibrium occurs when
a substance is in equilibrium between two states
a solid substance is in a saturated solution
Equilibrium is a dynamic process.
true
false
At equilibrium, the concentrations of all components are equal
true
false
The equilibrium position depends on the initial concentrations of materials.
true
false
The concentrations of each substance in an equilibrium expression is measured in
L/mol
moles/L
The value of the equilibrium constant is affected by
volume
temperature
The equilibrium constant symbol is
Keq
keq
For the reaction: CaCO3(s)←→CaO(s)+CO2(g), the equilibrium constant would be
.
[CaO][CO2][CaCO3]
[CO2]
A large equilibrium constant means that products are favored over reactants.
true
false
The units for the equilibrium constant vary depending on the reaction.
true
false
Balanced equations are needed before writing equilibrium constants.
true
false
At equilibrium, the concentrations of the substances are constant.
true
false
A chemical system in equilibrium can be disrupted by changes in all of the following except
time
temperature
Chemical equilibrium was studied by _________ .
the French chemist Henri Le Châtelier
the French chemist Pierre Le Châtelier
Addition of a catalyst to a reaction in equilibrium.
increases the rate of the reverse reaction
has no effect on the equilibrium
In a gas-phase reaction 2A + 3B →← 4C + D, an increase in pressure will.
have no effect on the equilibrium
have no effect on the equilibrium
In the equilibrium system A →← B, and increase in [A] will.
cause a decrease in the forward reaction
cause an increase in the forward reaction
In the equilibrium reaction CaCO3(s) →← CaO(s) + O2(g), a decrease in pressure produces.
an increase in the rate of the reverse reaction
an increase in the rate of the forward reaction
In the equilibrium reaction A + B →← C + D+ 87.5 kJ, an increase in temperature will produce
an increase in the reverse reaction
an increase in the forward reaction
After an equilibrium has been disturbed, the equilibrium position can be restored to its original position.
true
false
A change in pressure will always affect equilibrium.
true
false
If more N2 is added to the Haber-Bosch process, the ammonia concentration will increase.
true
false
Continued removal of ammonia in the Haber-Bosch process will force the reaction to completion.
true
false
The forward Haber-Bosch reaction is endothermic.
true
false
A change in pressure on a liquid or solid does not stress the system.
true
false
An increase in pressure causes gas molecules to be forced closer together.
true
false
A reaction will go to completion under all of the following situations except
formation of a nonionized compound
check
formation of an ionized compound
A reaction goes to completion when all of the following occur except
the reverse reaction slows down
the reverse reaction cannot establish itself
In the equilibrium system A →← B, an increase in [A] will
have no effect on the Keq
have variable effects on the Keq
A shift in equilibrium position is not the same as a change in Keq.
true
false
_________ salts tend to be very soluble
transition metals
alkali metals
The solubility product constant for Fe(OH)2 is written
[Fe2+][OH-]
[Fe2+][OH-]2
AgCl can still be considered a
weak electrolyte
strong electrolyte
NaCl is highly soluble in water.
true
false
PbCl2 is less soluble in water than PbCO3
true
false
The solid portion of an equilibrium equation appears in the Ksp expression.
true
false
Solubility is normally expressed as
grams/mL
grams/L
Molar mass is used to convert between solubility and molar solubility.
true
false
Solubility of a material can be used to calculate Ksp.
true
false
When two solution are mixed that could form a precipitate, equilibrium is attained when
the ion product is less than the Ksp
check
the ion product equals the Ksp
The common ion effect is an application of LeChâtelier’s principle.
true
false
One of the following is not a characteristic of exothermic reactions
products have lower stability than reactants
products are more stable than reactants
One of the following is not a characteristic of an endothermic reaction
products are less stable than reactants
reaction is energetically favorable
Most naturally occurring reactions are exothermic.
true
false
The energy of the system increases during an exothermic reaction.
true
false
One of the following does not show an increase in entropy
solid reactant forms liquid product
CO2 condenses to form dry ice
A decrease in entropy can be seen when
sugar is crystallized out of solution
sugar is dissolved in water
A decrease in entropy is seen when
Hydrogen and oxygen form water
NaCl is dissolved in water
Chemical reactions tend to proceed in a way as to decrease the entropy of the system.
true
false
Work must be done to decrease entropy.
true
false
Is entropy increasing or decreasing in the reaction 2Al(s) + 3Br2(g) → 2AlBr3(s)
increasing
decreasing
Is entropy increasing or decreasing in the reaction2CO(g) + O2(g) → 2CO2(g)
increasing
decreasing
Is entropy increasing or decreasing in the reaction 2HgO(s) → 2Hg(l) + O2(g)
increasing
decreasing
Is entropy increasing or decreasing in the reaction 2Cl2O5(g) → 2Cl2(g) + 5O2(g)
increasing
decreasing
Is entropy increasing or decreasing in the reactionCa(s) + 2H2O(l) → Ca(OH)2(aq) + H2(g)
increasing
decreasing
Is entropy increasing or decreasing in the reaction3Li2CO3(aq) + 2Al(NO3)3(aq) → 6LiNO3(aq) + Al2(CO3)3(s)
increasing
decreasing
The symbol for entropy is
S
E
The units for entropy are
J/K•mol
K/J•mol
Standard entropy change can be calculated using
ΔS∘=∑nS∘(products)-∑nS∘(reactants)
ΔS∘=∑S∘(reactants)-∑S∘(products)
All molecular motion ceases at 0 degrees K.
true
false
The standard entropy of a substance is given by S°.
true
false
The entropy change for the vaporization of water is negative.
true
false
A combustion reaction is considered to be spontaneous because
the energy of the system increases
reaction is exothermic
All of the following are characteristics of non-spontaneous reactions except
entropy increases
reaction is endothermic
The release of CO2 when carbonic acid is dissolved in water is spontaneous because
the entropy of the system is increased
the equilibrium favors the forward reaction
Situations associated with NO formation involve all but one of the following
highly endothermic
negative entropy change
The formation of NO from nitrogen and oxygen in the atmosphere is non-spontaneous at normal temperatures and pressures.
true
false
A spontaneous reaction is one that occurs rapidly.
true
false
Changes in enthalpy and entropy are the driving forces behind all chemical reactions.
true
false
Entropy decreases during most combustion reactions.
true
false
Formation of carbonic acid after CO2 is added to water is a non-spontaneous reaction
true
false
Units for ∆G are
J/mol
kJ/mol
If ∆H is positive and ∆S is negative, then ∆G is
never negative
always negative
If ∆H is negative and ∆S is positive, then ∆G is
never negative
always negative
Free energy is energy that is
used to drive the reaction
available to do work
Spontaneous reactions release free energy as they proceed.
true
false
The symbol for free energy is in honor of the American scientist James Gibbs.
true
false
∆G must be negative for a spontaneous reaction.
true
false
When the T∆S term becomes larger than the ∆H term, the ∆G value will be
positive if ∆S is positive
negative if ∆S is positive
When a reaction is exothermic, the ∆H term needs to be larger than the T∆S term for the reaction to be spontaneous.
true
false
To determine the temperature at which ∆G changes sign, we calculate
the equation for ∆H = zero
the equation for ∆G = zero
In the quicklime manufacturing process
measurable CO2 is detected at 300°C
measurable CO2 is detected above 700°C
At the temperature at which a change of state occurs, all of the following are true except
∆G = zero
∆Sfus = zero
The ∆H° for the quicklime reaction is positive at 25°C.
true
false
The entropy for the quicklime reaction decreases as the reaction proceeds.
true
false
The entropy change during the melting of ice can be calculated using ∆Hvap.
true
false
The ∆G value = zero at the equilibrium point in the ice-water system.
true
false
The variable R is the
ideal gas constant
gas constant
When Keq is large, ∆G should be negative.
true
false
