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WorksheetsMidterm Exam in Chemistry
Total questions: 50
Worksheet time: 1hrs 20mins
What is the oxidation number of oxygen in water?
-1
-2
0
+1
+2
2CaO--> 2Ca + O2
2Ca(s) + O2(g) --> 2CaO(s), calcium is __________
which element, if any, is oxidized?
4Fe + 3O2 --> 2Fe2O3
WRITE THIS OUT ON PAPER, YOU MAY USE THE ANSWER TO THIS PROBLEM AGAIN IN ANOTHER QUESTION:
Balance the following ACIDIC reactions using the half-reaction method.
MnO4−(aq) + H+(aq) + I− (aq) → Mn2+(aq) + I2(s)
Water is a product of this reaction. What is the coefficient of water in the final balanced equation?
8
5
2
16
WRITE THIS OUT ON PAPER, YOU MAY USE THE ANSWER TO THIS PROBLEM AGAIN IN ANOTHER QUESTION:
Balance the following reactions using the half-reaction method.
MnO4−(aq) + H+(aq) + I− (aq) → Mn2+(aq) + I2(s)
How many electrons did you cross out on both side?
1 e-
2 e-
5 e-
10 e-
WRITE THIS OUT ON PAPER, YOU MAY USE THE ANSWER TO THIS PROBLEM AGAIN IN ANOTHER QUESTION:
Consider the following REDOX reaction:
Cl2(g) → ClO−(aq) + Cl−(aq) (basic solution)
How many OH- molecules did you add to the reactant side of this reaction when balancing?
1
2
3
4
___________________ is the capacity to do work or supply heat.
energy
heat changes
specific heat
thermochemistry
Ice cream melting is an example of an __________ process. (heat enters the system from the surroundings)
endothermic
exothermic
Sweating is an __________________ process because heat is released.
endothermic
exothermic
what does c stand for?
heat capacity
specific heat
mass
temperature
Mass must always be in ________ for energy calculations.
kilograms
grams
joules
calories
What is the specific heat of water?
4.184 J/gC
1.00 cal/gC
All of the above
none of the above
When heat flows from system to the surroundings that is an example of an ________________ process.
exothermic
endothermic
What device is used to measure the amount of heat involved in a chemical reaction or physical process?
barometer
calorimeter
thermometer
Kinetic energy is energy gained _______________
while at rest
during motion
What is calorimetry?
process of measuring kinetic and potential energy
process of measuring heat flow of chemical reactions
process of measuring pressure and temperature of a substance
Heat flows from _______ to _________.
warm to cool
cool to warm
What area of study in chemistry is concerned with the heat transfers that occur during chemical reactions?
stoichiometry
thermochemistry
inorganic chemistry
physical chemistry
The specific heat of a substance varies with the mass of a sample. True or False?
True
False
1 calorie = _______ Joules
1000
1
500
4.184
Samples of two different substances having the same mass always have the same heat capacity. True or False?
True
False
The unit for q (heat energy) can be in joules or calories. True or false?
true
false
The law of conservation of energy states that
in any chemical or physical change, energy cannot be created or destroyed, only changed in form.
heat changes occur during chemical and physical changes.
energy is the capacity to do work or to supply heat
there are two types of energy, kinetic and potential
1000 calories = ____ kcal
10
100
1
1000
In energy calculations, temperature must be in which unit?
Fahrenheit
Kelvin
Celsius
How can you find the change in temperature?
Tfinal + Tinital
Tfinal − Tinitial
none of the above
What is a redox reaction?
A reaction where both reactants get reduced.
A reaction where both reactants get oxidized.
A reaction that involves a transfer of electrons between reactants.
A reaction that involves the combustion of at least one reactant.
What is reduction?
It is the gain of electrons.
It is the loss of electrons.
It is the creation of electrons.
It is the destruction of electrons.
What is oxidation?
It is the gain of electrons.
It is the loss of electrons.
It is the creation of electrons.
It is the destruction of electrons.
What is a reducing agent?
It is the species that gets reduced -- gains electrons.
It is the species that gets oxidized -- loses electrons.
It is the species that creates electrons.
It is the species that destroys electrons.
What is an oxidizing agent?
It is the species that gets reduced -- gains electrons.
It is the species that gets oxidized -- loses electrons.
It is the species that creates electrons.
It is the species that loses electrons.
What is a galvanic (voltaic) cell?
It is a cell that destroys electrons on one side and creates electrons on the other side.
It is a cell that contains only one metal bar and one aqueous ion solution.
It is a type of battery that drives a redox reaction when electricity is applied.
It is a type of battery that generates an electrical current from redox reactions.
What is a standard half-cell?
It is one cell that comprises half of a whole battery.
It is a cell containing only a metal bar with no aqueous ion solution.
It is a cell containing only an aqueous ion solution and no metal bar.
It is a cell that generates half of a volt of electricity.
What is a half-reaction?
It is a reaction at equilibrium where half of the substances are reactants and half of the substances are products.
It is the reaction that occurs when the switch of a galvanic cell is open.
It shows EITHER the reduction component or the oxidation component of a redox reaction.
It shows BOTH the reduction and oxidation components of a redox reaction.
What is an anode?
It is the electrode where oxidation takes place.
It is the electrode where reduction takes place.
It is an aqueous solution containing an electrode.
It is the salt bridge that connects half-cells.
What is a cathode?
It is the electrode where oxidation takes place.
It is the electrode where reduction takes place.
It is an aqueous solution containing an electrode.
It is the salt bridge that connects half-cells.
C(s, graphite) + 1⁄2O2(g) --> CO(g) cannot be measured directly since some carbon dioxide is always formed in the reaction.
It can be calculated using Hess’s Law and the enthalpy changes of combustion of graphite and of carbon monoxide.
C(s, graphite) + O2(g) --> CO2 ΔH=-394 kJmol–1
CO(g) + 1⁄2O2(g) --> CO2 ΔH=-283 kJmol–1
The enthalpy change for the reaction of graphite with oxygen to give carbon monoxide is
Which one of the following expressions gives the correct value for the standard enthalpy change of formation of methane in kJ mol–1?
C(s) + 2H2(g) → CH4(g)
Which statement about this information is correct?
than the total energy of the bonds
formed in the product
Electrochemistry deals with
electric energy
chemical energy
only a
both a & b
Electronic conduction is due to flow of
Protons
Electrons
Neutrons
Ions
A chemical species in an electrochemical reaction that LOSSES electrons undergoes _________.
Oxidation Reaction
Reduction Reaction
It is is the positive or oxidizing electrode that acquires electrons from the external circuit and is reduced during the electrochemical reaction.
Anode
Cathode
Electrode
Diode
