A. 51. 9 kJ/g B. 195 kJ/g C. 69  104 kJ/g D. 39  1026 kJ/g Remember that you need to use the periodic table to get the mass of ethane in g/mole. The heat of combustion of methane, ch4, is 50. 1 kJ/g



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Quiz 7 Key

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

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

2.  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

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

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.

This could also be called "conservation of energy".

4.  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.

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

5.  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.

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

6.  Combustion is a chemical process in which a fuel combines with______ to release energy and form products.  
A.  nitrogen
B.  oxygen
C.  methane
D.  hydrogen

Remember that this gas is considered a fuel for any combustion.

7.  Which is a fossil fuel?  
A.  wood
B.  uranium
C.  ethanol
D.  natural gas

Remember that fossil fuels are formed of plants and animals that lived millions of years ago and now are transformed.

8.  In the petroleum industry, what does a refinery do?  
A.  It separates crude oil into fractions consisting of compounds with similar boiling points.
B.  It separates crude oil from the coal with which it is almost always found.
C.  It mixes natural gas or coal with crude oil in order to remove the impurities from the crude oil.
D.  It produces the machinery by which crude oil is removed from the ground.

Remember that many different end products come from a barrel of oil.

9.  Petroleum (crude oil) is a complex mixture of thousands of substances, the majority of which are  
A.  carbohydrates.
B.  hydrocarbons.
C.  natural gases.
D.  proteins.

Remember that oil contains compounds of varying molar masses but mostly comprised of hydrogen and carbon. 

10.  The process by which a solution is heated to its boiling point and the vapors are condensed and collected is known as  
A.  combustion.
B.  cracking.
C.  crystallization.
D.  distillation.

This is a method of purifying substances that is used widely in industry.

11.  During petroleum refining, catalysts play an extremely important role during the  
A.  cracking and reforming processes.
B.  environmental cleanup of oil wells.
C.  extraction of the oil from the earth.
D.  physical separation of the various components of the petroleum.

Remember that these are used at the refinery after distillation.



12.  The diagram below shows a simplified version of a fractionating column used in the petroleum industry.

  
The position marked ___ corresponds to the cracker where large molecules are broken into smaller molecules.  
A.  A
B.  B
C.  C
D.  D

Remember that the cracker will split compounds found lower in the column into two other portions.

13.  Which of the following is not a "clean coal" technology already in use?  
A.  “Coal washing” to remove sulfur and other mineral impurities from the coal before it is burned.
B.  “Gasification” to convert coal to a mixture of carbon monoxide and hydrogen. The resulting gas burns at a lower temperature, thus reducing the generation of nitrogen oxides.
C.  “Wet scrubbing” to chemically remove SO2 before it goes up the smokestack. This is accomplished by reacting the SO2 with a mixture of ground limestone and water.
D.  "Sequestration" to capture and store CO2 before it is emitted into the atmosphere.

Remember that clean coal is about reduction of pollution not greenhouse gases.

14.  Which of the following has the highest boiling point?  
A.  Propane
B.  Octane
C.  Methane
D.  Butane

Remember that higher molar mass leads to higher boiling point.



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 31% and your furnace is 85% efficient in converting electrical energy into heat energy.  What mass of natural gas the power plant must burn if heating your home requires 3.5  107 kJ?  The heat of combustion of natural gas is 50.1 kJ/g.   
A.  2650 kg
B.  8550 kg
C.  2250 kg
D.  10,100 kg

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.


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