Question 1

The heat of combustion of ethane,C₂H₆,is 1560 kJ/mol.What is the heat of combustion of ethane,in kJ per gram? A)51.9 kJ/g B)195 kJ/g C)4.69 × 10⁴ kJ/g D)9.39 × 10²⁶ kJ/g

Accepted Answer

Remember that you need to use the periodic table to get the mass of ethane in g/mole.

Question 2

The energy of motion is called _________ energy.
A)electrical
B)mechanical
C)potential
D)kinetic

Accepted Answer

Remember that potential energy is stored while this type of energy is for motion of any thing.

Question 3

The first law of thermodynamics states that
A)energy is the capacity to do work.
B)doing work is defined as causing movement against a resisting force.
C)heat flows from a warmer body to a cooler body.
D)energy is neither created nor destroyeD.

Accepted Answer

This could also be called "conservation of energy".

Question 4

The energy needed to initiate a chemical reaction is called the
A)heat of combustion.
B)bond energy.
C)activation energy.
D)renewable energy.

Accepted Answer

This is the energy necessary to start or activate a reaction.

Question 5

The energy stored in the chemical bonds of fossil fuels is a form of ______ energy.
A)electrical
B)mechanical
C)potential
D)kinetic

Accepted Answer

Remember that kinetic energy is the energy of motion while potential energy is stored.

Question 6

In an exothermic chemical reaction
A)the mass of the products is greater than the mass of the reactants.
B)the mass of the products is less than the mass of the reactants.
C)heat is released as the reaction proceeds.
D)heat is absorbed as the reaction proceeds.

Accepted Answer

Remember the exo- means "out of".

Question 7

The conclusion that it is impossible to completely convert heat into work without making other changes in the universe is
A)based on erroneous observations.
B)the concept that increasing entropy characterizes all changes in the universe.
C)another way of stating that all energy is either thermal energy or heat.
D)the second law of thermodynamics.

Accepted Answer

Remember that there is no perfect machine as stated by this law of thermodynamics.

Question 8

A calorie is defined as exactly 4.184 J.Therefore 1.000 Cal is exactly
A)41.84 J.
B)418.4 J.
C)1000 J.
D)4184 J.

Accepted Answer

Remember that a Cal is 1000 cal.

Question 9

The heat of combustion of methane,CH₄,is 50.1 kJ/g.How much heat would be generated if 1.00 mol of methane undergoes complete combustion? A)0.32 kJ B)3.12 kJ C)601 kJ D)804 kJ

Accepted Answer

Remember that one mole of methane has a mass of 16 g.

Question 10

In which example is the entropy of the initial state greater than the entropy of the final state?
A)A building collapses during an earthquake.
B)A lump of sugar dissolves in a cup of warm water.
C)Liquid water freezes into ice.
D)Liquid water evaporates.

Accepted Answer

Remember that an increase in entropy means an increase in disorder in the system.

Question 11

How is heat energy used to generate electricity in a modern power plant?
A)Heat warms wires causing electrons to move through them more rapidly.
B)Heat boils water to make steam,which drives a turbine.
C)Heat warms the fins on a turbine,causing them to spin.
D)Heat generates strong magnetic fields through which the wires of a turbine move.

Accepted Answer

Remember that water is useful to absorb large amounts of heat energy.

Question 12

In a typical power plant,the combustion of a fuel is used to boil water.The steam then causes a turbine to spin.At this stage,the potential energy of the fuel has been transformed into _________ energy of the spinning turbine.
A)kinetic
B)mechanical
C)electrical
D)potential

Accepted Answer

This refers to the energy of the machine,not just the energy of motion.

Question 13

Based on this reaction and its energy profile, CH₄(g)+ 2O₂(g)→ CO₂(g)+ 2H₂O(g) The reaction A)is exothermic. B)is endothermic. C)has a high activation energy. D)violates the first law of thermodynamics.

Accepted Answer

Remember that -exo mean out of while -endo means into.

Question 14

The energy that flows from a warmer body to a colder body is called
A)heat.
B)temperature.
C)potential.
D)work.

Accepted Answer

Remember that temperature tells about direction of heat flow.

Question 15

Assume that an extremely inefficient electrical utility company delivers electrical energy to your home from a natural gas-burning power plant with an overall efficiency of only 21% and your furnace is 100% efficient in converting electrical energy into heat energy.What mass of natural gas must be burned by the power plant if heating your home requires 3.5 × 10⁷ kJ? The heat of combustion of natural gas is 50.1 kJ/g. A)1.5 × 10⁵ g B)3.3 × 10⁶ g C)3.7 × 10⁸ g D)8.4 × 10⁹ g

Accepted Answer

You should find the energy required at 100% efficiency then scale up to the higher number required due to the inefficient plant.That is the number to use to convert to amount of fuel needed.

Question 16

The energy equivalent of a certain cheeseburger is approximately 525 Cal.Since 1 Cal is 4.184 kJ this corresponds to
A)1.25 kJ.
B)125 kJ.
C)220 kJ.
D)2200 kJ.

Accepted Answer

Remember to multiply Cal time kJ to get the answer.

Question 17

Any chemical or physical change that absorbs energy
A)has high activation energy.
B)is an endothermic process.
C)is an exothermic process.
D)is a catalyzed process.

Accepted Answer

Remember that endo- means into the system.

Question 18

The property of matter that determines the direction of heat flow is the
A)mass.
B)temperature.
C)volume.
D)density.

Accepted Answer

Only one of these can be used to determine information about thermal energy.

Question 19

A chemical reaction accompanied by a release of energy is called a/an ______ reaction.
A)endothermic
B)catalyzed
C)exothermic
D)fast

Accepted Answer

Remember that the energy exits the system.

Question 20

The measure of how much energy is dispersed in a given process is called the
A)entropy.
B)activation energy.
C)heat of combustion.
D)potential energy.

Accepted Answer

Remember that this is the small amount of energy that is lost and never allows any system to be 100% efficient.

Quiz 4: Energy From Combustion

The heat of combustion of ethane,C₂H₆,is 1560 kJ/mol.What is the heat of combustion of ethane,in kJ per gram?

The energy of motion is called _________ energy.

The first law of thermodynamics states that

The energy needed to initiate a chemical reaction is called the

The energy stored in the chemical bonds of fossil fuels is a form of ______ energy.

In an exothermic chemical reaction

The conclusion that it is impossible to completely convert heat into work without making other changes in the universe is

A calorie is defined as exactly 4.184 J.Therefore 1.000 Cal is exactly

The heat of combustion of methane,CH₄,is 50.1 kJ/g.How much heat would be generated if 1.00 mol of methane undergoes complete combustion?

In which example is the entropy of the initial state greater than the entropy of the final state?

How is heat energy used to generate electricity in a modern power plant?

In a typical power plant,the combustion of a fuel is used to boil water.The steam then causes a turbine to spin.At this stage,the potential energy of the fuel has been transformed into _________ energy of the spinning turbine.

Based on this reaction and its energy profile, CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(g) The reaction

The energy that flows from a warmer body to a colder body is called

The energy equivalent of a certain cheeseburger is approximately 525 Cal.Since 1 Cal is 4.184 kJ this corresponds to

Any chemical or physical change that absorbs energy

The property of matter that determines the direction of heat flow is the

A chemical reaction accompanied by a release of energy is called a/an ______ reaction.

The measure of how much energy is dispersed in a given process is called the