Chemistry (CHM1020) Final Exam
The following molecules contain only single bonds. NH3(g) + 3F2(g) → NF3(g) + 3 HF(g) The bond energies are: N — H 391 kJ/mol; F — F 158 kJ/mol; N — F 272 kJ/mol; H — F 566 kJ/mol. Which is the heat evolved or absorbed per mole of NH3 that reacts with F2?
-867 kJ/mol
Hard water in parts of the Midwest may have a calcium ion concentration as high as 400 ppm. What is this calcium ion concentration when expressed as a percentage?
0.04 percent
A propane grill was used for an hour and produced 1.5 kg of carbon dioxide (CO2). What is the mass of carbon atoms produced in this amount of CO2?
0.41 kg
Choose the proper coefficients for each substance to balance this equation. ____ C2H4(g) + ____ O2(g) → ____ CO2(g) + ____ H2O(g)
1, 3, 2, 2
What is the molarity of sodium chloride in a solution containing 0.50 mol of sodium chloride in 500 mL of water?
1.0 M
Calculate the mass of 25,000 molecules of nitrogen gas. (1 mole = 6.02 × 1023 molecules)
1.16 × 10^-18 g
Calculate the mass of 2.50 × 10^4 molecules of nitrogen gas.
1.16 × 10^¯18 g
There are approximately 2 × 10^22 molecules and atoms in each breath we take and the concentration of CO in the air is approximately 9 parts per million. Approximately how many CO molecules are in each breath we take?
1.8 × 10^17
How many cm are in 0.129 m?
12.9 cm
Balance this equation P4 + Cl2 → PCl5 with the smallest whole number coefficients. Choose the answer that is the sum of the coefficients. (Do not forget coefficients of "one.")
15
A coal-burning power plant generates 6.0 x 1016 J per year. If the combustion of coal yields 29 kJ/g, how many grams of coal was burned each year?
2.1 x 10^12 g
A Big Mac® has a nutritional value of 563 Calories. Assuming that all the energy produced from consuming the burger goes towards keeping your heart beating, approximately how many days can the Big Mac sustain a heartbeat of 82 beats/minute? (Note: 1 Cal = 1000 cal, 1 cal=4.184 J, 1 heartbeat requires 1 J of energy)
20 days
What is the balanced chemical equation for the complete combustion of ethane (C2H6) to produce carbon dioxide and water?
2C2H6 (g) + 7O2 (g) ----> 4CO2 (g) + 6H2O (g)
Which is the correct balanced equation for the complete combustion of ethane in excess oxygen?
2C2H6 + 7O2 → 4CO2 + 6H2O
Hydrogen gas (H2) is a promising alternative to fossil fuels. How many molecules are present in 1.0 kg of hydrogen gas?
3.0 × 10^26
A sample of hard water has a Ca^2+ concentration of 135 ppm. What is the concentration in units of molarity?
3.37 x 10^-3 M
The heat of combustion of butane (C4H10) is 91.4 kJ/g. How much heat is produced if 7.0 moles of butane undergoes complete combustion?
3.7 x 10^4 kJ
What is the answer to the following mathematical operation? (1.42 + 9.4) × 2.854
30.9
What is the molar mass of the drug Flunitrazepam (C16H12FN3O3)?
313.3 g/mol
A calorie is defined as exactly 4.184 J. Therefore 1.000 Cal is exactly
4184 J.
The pH of rain water falling through an unpolluted atmosphere is closest to
5.4.
The heat of combustion of ethane, C2H6, is 1560 kJ/mol. What is the heat of combustion of ethane, in kJ per gram?
51.9 kJ/g
What mass of K2SO4 is required to make a 600.0 mL K2SO4 solution with a concentration of 0.50 M?
52 g
The Aurora Borealis is caused by ionizing radiation interacting with the Earth's magnetic field and the upper atmosphere. The distinctive green color is caused by the interaction of the radiation with oxygen and has a frequency of 5.38 x 1014 Hz. What is the wavelength of this light?
558 nm
A coal-burning power plant generates electrical power at a rate of 750 megawatts (MW), or 7.50 x 108 J/s. The plant has an overall efficiency of 39 % for the conversion of heat to electricity. Given this efficiency, how much heat energy in joules (J) is produced in one year of operation?
6.1 x 10^16 J
A hot dog has a nutritional value of 290 Cal. How many 20 kg dumbbells could be lifted 1 m off the floor with the amount of energy obtained from metabolizing one hot dog? (Note: It requires 200 J of energy to lift a 20 kg dumbbell 1 m of the floor; 1 Cal = 1000 cal; 1 cal = 4.184 J)
6067
The color orange within the visible spectrum has a frequency of 4.8 x 1014 Hz. What is the wavelength of orange light?
625 nm
The quantity 8.7 × 10^5 g expressed in standard decimal notation.
870,000 g
Which differentiates a compound from a mixture of two or more elements?
A compound does not exhibit the individual properties of the elements of which it is composed
In which example is the entropy of the initial state lower than the entropy of the final state?
A pot of water boils to produce water vapor at 100°C
Which one of these materials is most likely to conduct heat?
A titanium rod
In the initial sequence of Thorium-232 decay, an alpha particle is emitted followed by a beta particle. What is the product of these two steps?
Actinium-228
An inversion layer happens when a certain weather pattern traps cooler air near the surface of the earth with a warmer air mass above it. Why is this a problem?
Air pollution concentrates in the inversion layer
In their fifth and most recent report published in 2014, the vast majority of scientists agreed on several key points. Which of the following is NOT one of those points?
All these choices were mentioned as key points: Human activities (primarily the combustion of fossil fuels and deforestation) are responsible for much of the recent warming The Earth is getting warmer If the rate of greenhouse gas emissions is not curtailed, our water resources, food supply, and even our health will suffer
What type of radiation is given off in this nuclear reaction? 210/84PO ----> 206/82Pb + _______
Alpha
Rank the forms of nuclear radiation from highest to lowest mass.
Alpha, beta, gamma
Which of the following is not carried out by bacteria in soil?
Ammonium is converted into nitrites Nitrites are converted to nitrates Atmospheric nitrogen is fixed in soils
The ozone hole is most prominent on the Earth over
Antarctica.
What is the relationship between stratospheric levels of atomic chlorine and ozone?
As chlorine increases, ozone decreases
What type of radiation is given off in this nuclear reaction? 14/6C ----> 14/7N + _________
Beta
Scientists have correlated average global temperature with atmospheric carbon dioxide levels for the last 160,000 years using ice cores from Antarctica. How is the carbon dioxide level determined?
By measuring the CO2 concentration in trapped air bubbles in the ice layers
Which of these is not a trihalomethane?
CH3Cl
Catalytic converters reduce the amount of _________ in car exhaust.
CO
Which component of the air makes up approximately 100 times more of an exhaled breath than of an inhaled breath?
CO2
Although carbon dioxide is the primary compound discussed with respect to global warming; of the common atmospheric components the global warming potential (GWP) of a carbon dioxide molecule is very low. Which statement best explains this pair of facts?
CO2 exists in relatively high concentrations
What is the chemical formula for carbon disulfide?
CS2
Which compound is insoluble in water?
Calcium carbonate
Which country is the world's leading producer of rare earth elements?
China
Which product of the ultraviolet decomposition of CFCs acts as the catalyst for ozone decomposition?
Chlorine atoms
Which is not a form of chlorine used to disinfect water?
Chloroform
Smokestacks at these plants release sulfur oxides and carbon dioxide into the air.
Coal-burning plants
Identify the single most effective strategy to reduce carbon dioxide emissions.
Develop alternate energy sources that do not rely on fossil fuels
Both the Clinton and G.W. Bush administrations were unwilling to sign the Kyoto Protocol. What was their primary objection to the treaty?
Developing countries are not required to control greenhouse gas emissions
What term is defined as the flow of electrons from one location to another?
Electricity
Why is the mileage a vehicle gets less when burning E85 than 100 percent gasoline?
Ethanol has a lower heat of combustion
All zero greenhouse gas emission fuel sources are also renewable.
False
Which is produced in the greatest amount from a barrel of petroleum?
Gasoline
HCFCs are a temporary solution to the problem of ozone depletion and will be replaced over the next 20 years by which class of compounds?
HFCs
How is heat energy used to generate electricity in a modern power plant?
Heat boils water to make steam, which drives a turbine
Which best symbolizes the hydrogen bonding between two water molecules? Hydrogen Oxygen
Hydrogen bonding with oxygen
When table sugar (sucrose, C12H22O11) dissolves in water, which type(s) of attraction between water and sugar molecules occur(s)? I. hydrogen bonding II. polar-polar interactions III. covalent bonding
I and II only
What is the effect of the absorption of infrared energy on matter?
It increases the vibration of chemical bonds
Which is not a known advantage of natural gas over other fossil fuels?
It is far more abundant than any other fossil fuel
Predict the products of this reaction: KOH + HNO3 →
KNO3 + H2O
What sort of energy is associated with energy from wind?
Kinetic energy
Predict the products of the chemical equation: 3LiOH + H3PO4 →
Li3PO4 + 3 H2O
Oxygenated gasolines are blends of petroleum-derived compounds with oxygen-containing compounds. Which of the following oxygenated compounds has been discontinued in some states because of potential health risks?
MTBE
Which concentration is consistent with a basic solution?
M\OH- = 3.4 × 10^-3 M
Which of the following is not an advantage of locating wind turbines off-shore instead of on land?
Maintenance costs are lower off-shore
Which chemical equation shows the dissociation of magnesium hydroxide?
Mg(OH)2 → Mg^2+ + 2OH¯
What is the primary component of an exhaled breath?
N2
Which is the balanced chemical equation for the reaction of nitrogen (N2) with oxygen (O2) to form NO?
N2 + O2 → 2 NO
The chemical formula for nitrogen monoxide is
NO.
Which chemical components are given off in car exhaust?
NOx H2O CO2
To meet the electricity needs of the entire United States, a solar array the size of ________ would be required.
New Jersey
The "doping" of a semiconductor to improve its performance means
adding small amounts of other elements to the pure semiconductor to change the freedom of electron motion throughout the crystal.
The majority of N2O molecules in the atmosphere come from
bacterial removal of nitrate ions (NO3¯) from soil.
During petroleum refining, catalysts play an extremely important role during the
cracking and reforming processes.
A recent set of advertisements has a picture of an aluminum can with an aluminum-frame bicycle, along with a hypothetical quote from the can that reads: "I want to be a bike. Recycle me." The analysis of the life cycle of an item starting with its raw materials and ending with the used item becoming the raw material for new products is called
cradle-to-cradle.
Rank the following solutions in order of increasing concentration: a) 32.3 g of NaCl in 100 mL of water b) 0.10 mol of NaCl in 10 mL of water c) 62.1 g of NaCl in 1 L of water d) 0.25 M NaCl solution
d < c < a < b
P2O5 is the chemical formula for
diphosphorus pentoxide
The first law of thermodynamics states that
energy is neither created nor destroyed.
In a refinery, the components of petroleum are separated by
fractional distillation.
In an exothermic chemical reaction
heat is released as the reaction proceeds.
The energy that flows from a warmer body to a colder body is called
heat.
Petroleum (crude oil) is a complex mixture of thousands of substances, the majority of which are
hydrocarbons.
Which practices might be described as carbon sequestration? i. Planting trees ii. Deforestation iii. Pumping carbon dioxide deep into the ocean iv. Increasing combustion of fossil fuels
i and iii only
Identify possible consequences of global warming. i. A rise in sea level ii. An increase in average relative humidity iii. An increase in forest growth in the Northern Hemisphere iv. A weakening of ocean currents
i, ii, iii, and iv
Which substances are regulated by the Kyoto Protocol? i. argon ii. carbon dioxide iii. nitrogen iv. nitrous oxide v. sulfur hexafluoride
ii, iv, and v only
During the Antarctic spring, ozone is destroyed at a greater rate than it is formed
in polar stratospheric clouds. on the surface of atmospheric ice crystals. in a process that is catalytic.
The attractions between anions and cations throughout a crystal are known collectively as
ionic bonds.
Any chemical or physical change that absorbs energy
is an endothermic process.
Semiconductors, such as the element silicon, may be used in cells that convert solar radiation to electricity. One of the major difficulties encountered in using silicon is that it
is expensive to produce large quantities of extremely pure silicon.
The speed of light in air
is independent of the wavelength and frequency of light.
The energy of motion is called ________ energy.
kinetic
A(n) ________ is a fixed number of atoms held together by chemical bonds in a certain spatial arrangement.
molecule
The atomic number is the
number of protons in the nucleus.
Combustion is a chemical process in which a fuel combines with ________ to release energy and form products.
oxygen
Sunlight (solar radiation) may be turned directly into electricity using ________ cells.
photovoltaic
The fact that carbon (C) is less electronegative than nitrogen (N) means that in a C — N bond, the
shared electrons are closer to the N atom than to the C atom.
When only one pair of shared electrons is involved in a covalent bond, the linkage is called a ________ bond.
single
Fission is the process of creating energy by
splitting large nuclei to form smaller, more stable nuclei.
The property of matter that determines the direction of heat flow is the
temperature.
Cracking is
the breaking of larger molecules into smaller ones.
Green chemistry is
the design of products and processes that reduce hazardous substances.
A disadvantage of ozonation over chlorination is
the higher cost of ozonation and ozonation does not protect the water after the initial process is complete.
The O-to-O-to-O bond angle in an ozone (O3) molecule is not exactly 120° because
the nonbonding electron pair occupies greater space than the bonding pairs.
The Montreal protocol is a
treaty to reduce the amount of CFCs produced in the world.
A polar covalent bond is created when
two atoms share their bonding electrons unequally.
Ozone in our atmosphere is important because it
absorbs some UV radiation.
Waste created at these power plants must be stored indefinitely.
Nuclear plants
What are the major disadvantages of using ozone instead of chlorine to disinfect water?
Ozone decomposes quickly and does not provide long-term protection against possible contamination as the water is piped through a municipal distribution system
Which is correct?
Ozone forms by combining an oxygen atom with an oxygen molecule UV radiation will dissociate ozone into an oxygen atom and an oxygen molecule There is a dynamic steady state of ozone in the stratosphere
The burning of coal produces sulfur dioxide, SO2, a pollutant that slowly reacts in air to form SO3. Sulfur trioxide dissolves into airborne water droplets to form a very corrosive solution of sulfuric acid. Which is a product of burning coal that hastens the transformation of sulfur dioxide into sulfur trioxide?
Particles of ash
What is special about the South Pole versus the North Pole that leads to ozone depletion only at the south Pole?
Polar stratospheric clouds form almost exclusively at the South Pole
Which one of the following is a subatomic particle located in the center of the atom and has a positive charge?
Protons
Arrange these types of radiation in order of increasing energy per photon: gamma rays, infrared radiation, radio waves, visible light, UV (ultra violet).
Radio waves < infrared radiation < visible light < UV < gamma rays
Which air pollutant is the second-leading cause of lung cancer worldwide, behind tobacco smoke?
Radon
All of these pollutants can be detected by their odors except
SOx.
Which of the following fission products released from the Chernobyl reactor is dangerous because it concentrates in bones?
Sr-90
Which is a known risk associated with nuclear power plants?
The cooling water source can suffer thermal pollution
When assessing the risk of an air pollutant, which does not play a role in considering someone's exposure to the pollutant?
The toxicity of the pollutant
What two factors are considered when determining the risk assessment for air pollutants?
Toxicity and exposure
Which region of the ultraviolet spectrum is absorbed least by the atmosphere?
UV-A
Which statement is correct?
UV-C is the most energetic of the three forms of UV light
Which color of visible light has the shortest wavelength?
Violet
Which source of renewable energy has seen the greatest growth in the last decade?
Wind
Which of the following molecules are polar? a) H2S b) CO2 c) BCl3 d) H2O
a, d
In general, hydrogen bonds are
about 1/10 as strong as typical covalent bonds.
When it reaches its largest size, the ozone hole over the Antarctic is
about as large as North America.
