exam 2
Any substance that may be burned to produce heat or work is called a(n) ______
fuel
In the formation of ionic compounds a nonmetal will ______ electrons to form an ion with the same number of electrons as the nearest ______ gas.
gain; noble
A calorimeter is used to measure the _______ released or absorbed by a reaction.
heat
What is the net ionic equation for the reaction of barium nitrate and copper(II) sulfate in aqueous solution?
Ba2+(aq) + SO42-(aq) --> BaSO4(s)
Which of the following is an endothermic process?
Boiling water
Which of the following statements correctly describe the mole?
The number of particles in a mole is called Avogadro's number. One mole of any substance contains 6.02 x 1023 particles.
An ionic compound will produce an aqueous solution when the attraction between the __________ molecules and the ions is greater than the attraction between the ___________ themselves. Ion size and charge can also play a role in the solubility of ionic compounds.
water ions
an _____ agent is needed for combustion, alongside a fuel and ignition source.
oxidizing
The scale, which usually ranges between 0 and 14, indicates the acidity of a solution.
pH
When the __________ molecules of ethanol, C2H5OH, are added to water, the ethanol molecules __________.
polar; form hydrogen bonds with the polar water molecules
The concentration of arsenic in a drinking water supply is found to be 1.4 ppm. What is the concentration in units of mg/L?
1.4
Which of the following options correctly describes an exothermic reaction?
It releases more energy by forming product bonds than is needed to break reactant bonds.
Which change would be considered climate mitigation?
Using energy-efficient appliances
Fresh water found in an aquifer is located:
below ground
energy is required to ____ bonds while energy is released when bonds are _____
break formed
What is the correct systematic name for the ionic compound Li3N? Multiple choice question.
lithium nitride
A solution that contains equal concentrations of H+ and OH- ions is called a(n) _____ solution
neutral
Which occurrences or processes are expected to reduce the level of atmospheric carbon? i. Decaying plant and animal remains ii. The growth of trees iii. Formation of carbonate rock in the ocean iv. Animal respiration
ii and iii
Which of the following are considered possible effects of climate change?
Changes in freshwater distribution Rise in sea levels An increase in the incidence of insect-borne diseases
Which corresponds to the composition of the ion typically formed by magnesium?
D 12, 10, 2+
Which of the following equations correctly represents the neutralization reaction between H2SO4 and KOH in water?
H2SO4(aq)+2KOH(aq)→K2SO4(aq)+2H2O(l)
The levels of which of the following species will have an impact on the formation of the CaCO3 shells of marine organisms such as coral?
HCO3- CO32- CO2
Which of the following solvents would be best to dissolve pentane, a nonpolar hydrocarbon molecule?
Liquid carbon dioxide
Why are some lakes able to resist a decrease in pH when exposed to acidic precipitation and/or runoff?
The soils or rocks surrounding the lake may contain bases, which neutralize the acid.
In general, for molecular compounds of similar type, as the molar mass _____ the boiling point increases.
increases
What is the molarity of a 1.50-L solution containing 22.3 g of sodium chloride (NaCl)? The molar mass of NaCl is 58.44 g/mol.
0.254 M
Based on Table 6.2, how much energy is required to break a N-Cl covalent bond?
193 kJ/mol
What type of radiation is absorbed by all greenhouse gases?
IR radiation
What international agreement attempted to reduce greenhouse gas emissions?
Kyoto Protocol
Which of the following options correctly compare the effect of acid precipitation on lakes in different geological surroundings?
Lakes in granite areas tend to have lower pH values than lakes in limestone regions. Lakes in limestone regions have a higher acid-neutralizing capacity.
Predict the products of the chemical equation: 3 LiOH + H3PO4 →
Li3PO4 + 3 H2O
Which of the following gives the best explanation for why oil and water do not mix?
Oil does not mix with water because oil is nonpolar and water is polar.
Which one of the following compounds is considered to be a molecular compound?
PCl3
Which of the following human activities increase the levels of atmospheric CO2?
Respiration Replacing trees with cultivated crops Burning fossil fuels
Which of the following options correctly describe how to name an ionic compound?
When naming the anionic portion of the ionic compound, the element name is changed to end in -ide. The cation is named first and the anion second.
Isotopes are atoms of the same element that have the same _____ number but a different _____ number. This is because isotopes have the same number of protons but a different number of _____.
atomic; mass; neutrons
A substance that releases OH- ions in water is called a(n)
base
Which compound is insoluble in water?
calcium carbonate
The ability of a covalently bonded atom to attract the shared electrons is called
electronegativity
The attractions between anions and cations throughout a crystal are known collectively as
ionic bonds
Which of these units are commonly used to express heats of combustion?
kcal/g kJ/mol
The molar mass of any substance is the mass of 1 _______ of the particles of that substance.
mol
Which of the following CANNOT act as a greenhouse gas?
H2 Cl2
which compounds are not soluble at room temperature
I and II only CaSO4 PbCl2
Which of the following is NOT a likely consequence of increased carbon dioxide concentration in the atmosphere?
Increase in biodiversity
Which of the following statements correctly describe isotopes?
Isotopes have different numbers of neutrons. Each element's atomic mass is a weighted average of the masses of the elements' isotopes.
In order for a molecule to absorb IR radiation, which of the following must be true?
Its bond vibrations must involve a change in charge distribution.
An ecological footprint estimates the biologically productive space required to support a particular lifestyle. Which of the following are included in this estimate? Select all that apply.
Land Sea surface Fresh water
Which solution is acidic?
MOH− = 1.77 × 10−10 M
Match each ion to the correct description of its solubility when combined with an ion of opposite charge. Instructions
Na+;soluble in all combinations SO42-;soluble except with Sr2+, Ba2+, and Pb2+ CO32-;insoluble except with Group 1A cations or NH4+ Cl; soluble except with Ag+ and Hg22+
Which of the following are strong bases?
NaOH KOH
Which of the following are common oxidizing agents in combustion reactions?
O3 (g) H2O2 (l) O2 (g)
Match each of the following polyatomic ions with its correct name.
OH-hydroxide NO2-nitrite NO3-nitrate PO43-phosphate SO42-sulfate SO32-sulfite
Which of the following gases produce acidic solutions in water?
SO2 CO2 NO2
How is a calorie defined?
The energy needed to increase the temperature of 1 g of water by 1 oC
Which of the following are forms of potential energy?
The energy of an object suspended above the ground The energy stored in the chemical bonds of a compound
Which statement correctly describes the procedure used to predict the ion formed by Group 1 and Group 2 elements?
The metal loses enough electrons to attain the same number as its nearest noble gas.
A structural formula in which carbon-to-hydrogen bonds are not shown explicitly is called a(n) _____ structural formula.
condensed
Small changes in the average global temperatures are expected to have a(n) _______ impact on our climate.
huge
The majority of fuels in current use across the world are ______.
hydrocarbons
The species that forms when a proton associates with a molecule of H2O is known as the ____ ion.
hydronium
A base is a compound that releases _____ ions in aqueous solution.
hydroxide OH-
The main reason that water supplies are chlorinated is
to kill disease causing organisms in the water
The molecule shown has a _____ shape and the marked bond angle is approximately _____.
trigonal planar; 120o
Use bond energies (see table) to estimate the heat of combustion of C3H8.
-2024 kJ/mol
How many moles of sodium chloride are there in 250 mL of a 1.20 M sodium chloride solution?
.30
Calculate the mass of 2.50 × 104 molecules of nitrogen gas.
1.16 × 10−18 g
The numbers 1 through 4 are used to identify four different elements on the periodic table. Which element is expected to have 2+ charge when it forms an ion?
2
Approximately how many people on the Earth lack access to clean drinking water?
2,1 bil
How many atoms are present in 0.375 mol of palladium (Pd) atoms?
2.26 × 1023
A 4-L sample of water contains 80 µg of lead. What is this lead concentration, in parts per billion (ppb)?
20
Which of the following options correctly describe a 0.0050 M solution of glucose (molar mass 180.2 g/mol) in water?
20 mL of this solution contains 1.0 x 10-4 moles of glucose. This solution contains 9.01 x 105 ppb of glucose.
How much energy must be absorbed by 10 g of water to increase its temperature by 5 ∘C?
209 J
The standard temperature and pressure for reporting properties such as density are _____ and _______.
25°C 1 atm
How many bromide ions can combine with one ion of aluminum to form an ionic compound?
3
Numbers 1 through 4 are used to identify four different elements. Based on periodic table trends, which number identifies the element that is expected to have the greatest tendency to attract a shared pair of electrons?
3, Halogens
The recommended daily requirement of calcium is 1000 mg. Tap water in a Midwestern city contains approximately 150 mg Ca/L. A person living in the city who drinks two liters of water in one day would receive __________ percent of his/her RDA of calcium.
30
If C (carbon) releases 394 kJ/mol when burned, how many kJ of energy are released for each g of carbon burned?
32.8 kJ
In the combustion of methane, how many O-H bonds are formed?
4
The pH of lemon juice is approximately 2.40. At this pH, the hydronium ion concentration is closest to which concentration?
4.0 × 10−3 M
The atomic mass of magnesium is 24.31 g. Given that Avogadro's number is 6.02 x 1023, what is the average mass of one Mg atom?
4.04 x 10-23 g
What is the molarity of a solution that contains 5.0 ppm of tin?
4.2 x 10^-5M.
20.0 g of NaOH is weighed and dissolved in enough water to prepare a 0.10 M solution. What size volumetric flask would be required for this solution?
5.0 L
Write the balanced equation and draw Lewis structures of reactants and products to determine the number of C=O bonds formed during the combustion of propane.
6
A student wants to prepare exactly 250 mL of a 0.500 M aqueous potassium hydroxide solution. What mass of potassium hydroxide (molar mass = 56.10 g/mol) must the student dissolve in the 250 mL of solution?
7.01 g
The greenhouse and enhanced greenhouse effects refer to the return of approximately __________ percent and greater than __________ percent of the heat radiated by Earth.
80; 80
Although coal is a complex mixture of substances, its elemental composition can be approximated by the formula C135H96O9NS. Using this chemical formula, calculate the percentage, by mass, of carbon (C) in coal.
85%
The atomic mass of calcium is 40.08 g. Given that Avogadro's number is 6.02 x 1023, what is the average mass of 15 Ca atoms?
9.99 x 10-22 g
Which of the following correctly describe how Roman numerals are used in naming and writing chemical formulas?
A Roman numeral is included for any metal that can form more than one monatomic cation The ionic compound Fe(III) has a charge of +3.
Which of the following options correctly describes a greenhouse gas?
A gas that absorbs and traps infrared radiation, thus warming the atmosphere
Which statement correctly describes the procedure used to predict the ion formed by an element?
A metal loses enough electrons to attain the same number as its nearest noble gas.
Which of the following options correctly describe molecular polarity?
A molecule that contains only nonpolar bonds is nonpolar. A molecule that contains polar and nonpolar covalent bonds could be polar or nonpolar. Overall molecular polarity depends on the geometry of a molecule.
Which of the following options correctly describe the pH scale?
A solution with a pH of 3 is more acidic than a solution with a pH of 5 The more acidic a solution is, the lower its pH
Match each set of reagents used in the water treatment process with their purpose.
Al2(SO4)3 and Ca(OH)2; Flocculating agents Cl2, NaClO, or Ca(ClO)2;Antibacterial agents F;Prevents tooth decay
The compounds depicted in the illustration are classified as what type of compound? Multiple choice question.
Alcohols
Which of the following statements correctly define an aqueous solution?
An aqueous solution can have one or more solutes. An aqueous solution is a homogeneous mixture. Water is always the solvent in an aqueous solution
Which of the following statements correctly describe bond energy?
Bond energy values are always positive. The total energy required to break apart a molecule depends on the number and type of bonds.
Which of the following options correctly describes the reaction shown below? C3H8 (g) + 5O2 (g) → 3CO2 (g) + 4H2O (g) + 2,220 kJ
Burning 1 mole of C3H8 releases 2,200 kJ of heat.
Which of the following is the chemical formula for octane?
C8H18
Which of the following fuels would have the largest heat of combustion, in units of kJ/g?
CH4
Which gas is central to the discussion of global climate change?
CO2
Which of the following molecules is nonpolar?
CO2
Which reaction accounts for the fact that the pH of rain is naturally slightly acidic?
CO2 + H2O → H+ + HCO3−
Which of the following elements will form a cation?
Ca Rb
Which of the following formulas for ionic compounds are correct?
Ca3N2 CaO
he acid-neutralizing capacity of a lake or stream most often derives from the presence of __________ in the surrounding soil or rock.
CaCO3 (limestone)
Which of the following options correctly describe the bonding of carbon?
Carbon typically forms 4 covalent bonds. Before bonding carbon has 4 valence electrons. Carbon bonds to attain a total of 8 valence electrons.
All atomic masses are determined relative to the mass of an atom of _____.
Carbon-12
Which of the following options correctly describe variations in solar irradiance and its effect on Earth's climate?
Changes in the Earth's orbit can affect the amount of solar radiation that reaches the Earth. Seasonal variations in sunlight intensity affect local temperatures significantly.
Which explanation accounts for the fact that, on average, cloudy nights are warmer than clear nights?
Clouds are composed of water vapor and H2O is a strong greenhouse gas
Which of the following options correctly describe a fuel? Select all that apply.
Coal is a common fuel that has been used for centuries. Fuels can be burned to produce heat and/or work.
Which of the following processes release CO2 into the atmosphere?
Decomposition Combustion Respiration
Which of the following is an anthropogenic influence on the environment?
Diamond mining Airline transportation Landfills Cattle farming
Which techniques are used to desalinate water?
Distillation Reverse osmosis
Match each solar body with the primary type of radiation it emits.
Earth; infrared radiation Sun; ultraviolet, visible, and infrared radiation
Which statement best defines the first law of thermodynamics?
Energy can be neither created nor destroyed.
The most electronegative element is _______.
Fluorine
Which reaction most accurately represents the dissociation of nitrous acid (HNO2) in water?
HNO2 + H2O → H3O2+ + NO−
What is the name of C7H16?
Heptane
Which conclusion was considered "very likely" in the 2014 report of the Intergovernmental Panel on Climate Change?
Human-caused emissions are the main factor causing warming since 1951
Which of the following options correctly explain what is meant by the term "strong acid" in chemistry?
If a strong acid is dissolved in water there will be no undissociated acid molecules in solution. A strong acid dissociates completely in aqueous solution.
The world map shows the availability of safe drinking water around the world. Which statement is true?
In the United States and Canada, more than 90 percent of the population has access to clean water
Which of the following options correctly describe a condensed structural formula?
In the condensed formula CH3CH2CH2CH3, the carbon and hydrogen atoms are understood to be joined by single bonds. Carbon-to-hydrogen bonds are not drawn out explicitly.
Why is NH3 able to act as a weak base?
It reacts with H2O to release small amounts of OH- ions.
Which of the following options correctly describe the use of distillation as a desalination technique?
It requires a lot of energy to desalinate water by distillation. MSF distillation technique is a modern technique used on large scale. A new heating source used for distillation is solar power.
What is the modern metric unit of energy?
Joule (J)
Which of the following balanced equations correctly represents the dissociation of K2SO4 in water?
K2SO4 (s) → 2K+ (aq) + SO42- (aq)
Predict the products of this reaction: KOH + HNO3 →
KNO3 + H2O
Which one of the following compounds is considered to be an ionic compound?
LiF
According to the U.S. EPA, which of the following would be considered a water contaminant?
Mercury Arsenic
Which chemical equation shows the dissociation of magnesium hydroxide?
Mg(OH)2 → Mg2+ + 2OH−
If a solute dissolves in water to form a solution that does not conduct an electric current, the solute is a(n) _____________________
Nonelectrolyte
A compound is classified as an alcohol if it contains what type of bond?
O-H
Which of the following are methods of making seawater appropriate for drinking?
Reverse osmosis Distillation
What are methods used to remove ions from salt water?
Reverse osmosis Distillation Desalination
Which of the following statements correctly describe reverse osmosis?
Reverse osmosis utilizes pressure to move water. Most desalination plants utilize reverse osmosis.
How does ocean acidification affect marine organisms such as coral? Multiple choice question.
The CaCO3 in coral dissolves to replace the CO32- ions used up by excess H+ ions.
Which of the following options correctly describe exothermic and endothermic reactions?
The energy change for an endothermic reaction has a positive sign. Exothermic reactions produce heat when they occur.
Which of the following options correctly describe electronegativity and its trends? Select all that apply
The higher the electronegativity value of an element, the more strongly it attracts bonding electrons to itself. The element with the highest electronegativity is fluorine. Electronegativity increases from left to right in the periodic table.
Which of the following statements correctly describe the carbon cycle?
The main atmospheric form of carbon is CO2. CO2 is generated by the combustion of fossil fuels.
Which statement correctly describes the procedure used to predict the ion formed by nonmetal elements in Groups 15, 16, and 17?
The nonmetal gains enough electrons to attain the same number as its nearest noble gas.
Which of the following correctly reflects Avogadro's number?
There are 6.02 x 1023 atoms in 12 g of carbon-12.
Which of the following options correctly describe the enhanced greenhouse effect?
This effect has resulted in an increase in average global temperatures on Earth. Atmospheric gases trap and return more than 80% of the heat radiated by Earth.
The periodic table lists the atomic mass of nitrogen as 14.01. Which of the following options correctly interpret this value?
This is the average mass of an atom of nitrogen. This value takes into account the masses and abundances of the isotopes of nitrogen.
Reverse osmosis is illustrated in this diagram. What is this process used for?
To remove dissolved salts from sea water
Which of the following describe the purpose of the Kyoto Protocol? Select all that apply.
To set targets for reduced greenhouse gas emissions for participating countries To set legally binding limits on greenhouse gas emissions
Determine the shape or geometry of PH3. (Hint: Use the Periodic Table to arrive at the electron configuration for phosphorous.)
Trigonal pyramidal
Match each H+ concentration to its corresponding OH- concentration in aqueous solution.
[H+] = 1 × 10-10; [OH-] = 1 × 10-4 [H+] = 1 × 10-7; [OH-] = 1 × 10-7 [H+] = 3 × 10-7;[OH-] = 3 × 10-8 [H+] = 5 × 10-2; [OH-] = 2 × 10-13
Which of the following solutions are acidic?
[OH-] = 1 × 10-11 [H+] = 3 × 10-4 M
A strong base is _____.
a base that dissociates completely in water
The H+ ion released by an acid in water is often referred to as a proton because _____.
a hydrogen atom without an electron consists of a single proton
A substance that releases H+ ions in water is called a(n)
acid
The n in the name n-hexane indicates that ______.
all the carbon atoms are joined in a straight chain
Influences on the environment resulting from human activities are called _____ influences.
anthropogenic
ionic bond
attraction between oppositely charged ions
covalent bond
attraction between two nuclei and a shared pair of electrons
For any element, the atomic mass recorded on the periodic table is not a whole number since it is a(n) _____of the masses of its naturally occurring isotopes.
average
Normal seawater is slightly _____ with a pH of around _____. Multiple choice question.
basic; 8.2
Most fuels in current use across the world are hydrocarbons, meaning that they are made up of the elements _____ and ______
carbon hydrogen
The most abundant isotope of ________Correct Unavailable is the internationally accepted standard for determining atomic mass.
carbon, C, carbon-12, C-12, or carbon 12
When naming an ionic compound, the _____ is always named first. To name the anion, the root of the nonmetal name is added to the suffix _____.
cation; -ide
Combustion is best described as ________.
chemical reaction with oxygen to release energy
Which of the following are examples of fossil fuels?
coal natural gas petroleum
Nonpolar solvents are used for which of the following applications?
dry cleaning products drug production
An estimate of the biologically productive space necessary to support a particular standard of living is called a(n) _____.
ecological footprint
If a chemical reaction is reversible, it occurs in both the forward and reverse directions at once, allowing the system to reach a(n) _______ if the system is closed.
equilibrium
True or false: All ionic compounds are highly soluble in water.
false
True or false: Energy is required to form bonds.
false
Fuels formed by natural processes such as the decomposition of prehistoric organisms are called ________ fuels.
fossil
Lakes surrounded by __________ have very little acid-neutralizing capacity.
granite
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
According to the EPA, water contaminants _____
include anything that affects the taste of the water may affect water color are substances harmful to human health include radioactive materials
Acids are covalently bonded substances that nonetheless produce _____ when dissolved in water. The attraction between the polar acid molecule and polar H2O molecules causes the acid to _____ or break down to form ions.
ions; dissociate
The central oxygen atom in H2O is surrounded by four electron pairs. The two lone pairs occupy more space than the bonding pairs, causing the bond angle in H2O to be _____ the ideal angle of 109.5o.
less than
Radiative forcings _____.
may have either a cooling or a heating effect on Earth are factors that influence the balance of incoming and outgoing radiation on Earth
In general, a lone pair occupies _____ space than a bonding electron pair, and will therefore _____ the bond angle between bonding pairs.
more; decrease
The carbon cycle refers to the
movement of carbon through living organisms, the atmosphere, the sea, and the earth.
Hydrocarbons may have either straight or branched chains. A straight chain of carbon atoms is indicated by the prefix _____.
n-
Which of the following options are correct systematic names for ionic compounds?
potassium chloride copper(II) oxide
Factors that influence the balance of Earth's incoming and outgoing radiation are called _____.
radiative forcings
The chlorine-containing chemicals (HClO, ClO-, and Cl2) that remain in the water after the chlorination step in the water treatment process are called _____ chlorine.
residual
An acid that dissociates completely in aqueous solution is called a(n) ___ acid
strong
Methane has a _____ shape.
tetrahedral
Direct measurements of atmospheric CO2 levels in Hawaii show that since 1960 _____.
the CO2 levels in a given year fluctuate depending on the time of year the annual average CO2 levels have increased steadily
The bond energy of a C-H bond is ___.
the amount of energy consumed to break a C-H bond
The heat of combustion of a compound is best described as _____.
the amount of heat released when a specific amount of a substance burns
If the sign δ- is used to mark an atom in a covalent bond, it means that _____.
this atom has a higher electron density this atom has a partial negative charge this atom is more electronegative
True or false: A solution with pH equal to 3.2 is more acidic than a solution with a pH of 7.2.
true
True or false: Carbon dioxide is considered a nonpolar solvent.
true
A slice of pizza supplies 217 kcal (217 Cal). If a person weighing 140 lb expends 80 kcal per mile when walking at 2.0 miles per hour, approximately how long will it take to use up the calories from the pizza?
1 hour 20 minutes
A neutral solution is one that _____
contains equal concentrations of OH- and H+ ions
Sunspots typically occur about every _____.
11 years
Which of the following reflects the correct procedure to calculate the molar mass of CH2Cl2?
12.0 + 2(1.0) + 2(35.5) = 85.0 g/mol
Which of the following options correctly describe the concentration terms ppm and ppb?
1 ppm is equivalent to 1 mg/L. 1 ppb is equivalent to 1μg1L1μg1L.
What is the concentration of OH- ions in a solution that contains 1 × 10-3 M H+?
1 × 10-11 M
Which of the following options correctly describe the processes that contribute to ocean acidification?
1. Dissolved CO2 reacts with H2O to form H2CO3 2. Increased atmospheric CO2 leads to more CO2 dissolved in the ocean
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
Ethanol (C2H6O) is a common intoxicant and fuel produced from the fermentation of various grains. How many moles of ethanol are represented by 50.0 kg of ethanol?
1.09 × 103 mol
Evaluate the ratio MH+ (pH 3) / MH+ (pH 7).
10,000
Based on the following equation, which conversion factor can be used to determine how much energy is released when a certain amount of iso-octane burns? 2C8H18 (l) + 25O2 (g) → 16CO2 (g) + 18H2O (g) + 10,900 kJ
10,900kJ/2mol C8H18
The isotope Mg-25 isotope has _____ protons and _____ neutrons in its nucleus. Mg has an atomic number of 12.
12; 13
A 1 oz piece of dark chocolate supplies 720. kJ of energy. Convert this to kcal (nutritional calories or Cal) given that 1 kJ = 0.239 kcal.
172 Cal work: 720. kJ x 0.239Cal1kJ0.239Cal1kJ = 172 Cal
LP gas (liquid propane, C3H8) is the fuel used in gas grills as well as a main source of heat energy for many rural residences. What is the mass of 5.83 × 1017 molecules of liquid propane?
4.27 × 10¯5 g
CO2 emissions in China declined by 9 percent over the five-year period ending in 2000. If 5.00 × 108 metric tons (t) of CO2 was emitted in 1995, how much CO2 was released in 2000?
4.55 × 108 t
What, approximately, is the highest concentration of CO2 measured in the Earth's atmosphere in modern times?
415 ppm
What percentage of solar radiation that reaches Earth's atmosphere is absorbed by Earth?
46
Find the molar mass of ethanol, C2H6O.
46.07 g/mol
Carbon is in Group 14 (IVA) and has _____ valence electrons. In order to attain a full octet in its outer shell it will therefore form _____ covalent bonds.
4; 4
Most aquatic life in lakes cannot survive in water with a pH less than
5.0
The pH of a solution that contains 1×10−5 MH+1×10-5 M H+ ions is equal to
5.0
If propane burns according to the following equation, how much heat will be released when 0.250 mol of propane are burned? C3H8 (g) + 5O2 (g) → 3CO2 (g) + 4H2O (g) + 2,220 kJ
555 kJ
A molecule will absorb IR radiation if it is capable of vibrational mode _____. (Select all that apply.)
A C D
A sample of fuel is burned in oxygen, producing heat and light. Based on the first law of thermodynamics, which statement must be true?
A sample of fuel is burned in oxygen, producing heat and light. Based on the first law of thermodynamics, which statement must be true?
Which of the following options correctly defines an electrolyte?
A substance that conducts an electric current in aqueous solution
Which of the following options correctly describe the behavior of acids? Select all that apply.
Acids have a sour taste. An acid will cause the dye litmus to change from blue to pink. Acids dissolve carbonates, producing CO2 gas.
Which of the following is a characteristic reaction of acids?
Acids react with carbonates to produce carbon dioxide.
Which of the following options correctly describe how the chemical structure of a fuel impacts its heat of combustion?
As the number of hydrogen atoms per carbon atom decreases so does the heat of combustion. Hydrocarbons produce more energy per gram than alcohols or sugars, which contain greater number of oxygen atoms in their structure.
Which reaction represents an acid-base neutralization reaction?
Be(OH)2 + H2SO4 → BeSO4 + 2H2O
Which polyatomic ions are anions?
Bicarbonate Hypochlorite Acetate Hydroxide Nitrite
Which of the following options correctly describe the steps required to determine the shape of a molecule?
Both bonding and nonbonding electron pairs must be considered. The Lewis structure of the molecule must be drawn first. The shape of the molecule is dictated by the most stable arrangement of the outer electron pairs.
Which of the following are considered exothermic processes?
Burning a fuel Freezing water
Which human activity has the GREATEST net effect on atmospheric CO2 levels?
Burning fossil fuels
Marine organisms such as mollusks, sea urchins, and coral have shells composed of _____ and these species are affected by the levels of _____ ion in seawater.
CaCO3; CO32-
Which of the following reactions corresponds to the balanced reaction between calcium chloride and silver nitrate?
CaCl2 + 2AgNO3 → Ca(NO3)2 + 2AgCl
Which of the following statements describe the drawbacks of using chlorine-containing chemicals in the water treatment process?
Chlorine-containing chemicals can themselves be toxic. Chlorine can react with organic matter to form trihalomethanes (THMs). The taste and odor of residual chlorine is objectionable.
Which of the following statements correctly defines concentration?
Concentration is the ratio of the amount of solute to the amount of solution.
Which process plays the most important role in the greenhouse effect?
Energy radiated by the earth is absorbed by the atmosphere
True or false: A bond between O and H within any molecule is called a hydrogen bond.
False
Which of the following options correctly describe a fuel?
Fuels can be burned to produce heat and/or work. Coal is a common fuel that has been used for centuries.
An acid is a compound that releases _____ ions in aqueous solution. Multiple choice question.
H+
Which of the following are common products of combustion?
H2O CO2
Which of the following products form when a solution of HCl reacts with Ca(OH)2?
H2O (l) CaCl2 (aq)
Which of the following species play a role in maintaining the normal pH of seawater?
HCO3-, CO3^2-, H2CO3
Rank the following compounds, from lowest to highest boiling points. For your ranking, place the lowest-boiling compound on the top.
HCl HBr HI
Which of the following is the strongest type of intermolecular force?
Hydrogen Bond
Which of the following options correctly describe the effect of pH on life in a lake or stream?
If the pH drops to 4.0, a lake is essentially a dead ecosystem. Fish begin to be affected when the pH of a lake or stream drops below 6.0. Some hardy aquatic species can survive at a pH of below 5.0.
What is the effect of the absorption of infrared energy on matter?
It increases the vibration of chemical bonds
An acidic fog in Pasadena was found to have a pH of 2.50. Which expression represents this pH measurement?
MOH− = 3.2 × 10−12 M
Which concentration is consistent with a basic solution?
MOH− = 3.4 × 10−3 M
The fact that carbon (C) is less electronegative than nitrogen (N) means that in a C — N bond, the
N atom takes the electrons from the C atom forming C+ and N−.
Which greenhouse gases were specifically targeted by the Kyoto Protocol?
N2O hydrofluorocarbons CO2
Which of the following compounds would have the highest boiling point?
NH3
Which of the following molecules is polar?
NH3
A proton released by an acid in aqueous solution quickly reacts with water to form a hydronium ion. What product is formed when a proton reacts with ammonia (NH3)?
NH4+
The weak base NH3 reacts with H2O to form _____ and _____ ions.
NH4+ OH-
The release of _______ gas causes acid rain through formation of nitric acid, HNO3.
NO2
Which of the following gases cause acid rain?
NO2 SO3
Which of the following ions always form soluble ionic compounds?
NO3- NH4+ Na+
Which of the following species will be present in an aqueous solution of Na2CO3?
Na+ CO32-
Which of the following ion combinations will result in an ionic compound that has a balanced number of positive and negative charges?
Na+ and Br - 2 Li+ and S2- Ca2+ and 2 F -
Mixing which of the following will produce a precipitation reaction (give an insoluble product)?
Na2SO4(aq) and Ba(OH)2(aq)
Which of the following options correctly describes the effects of the observed increase in global temperatures over the last century?
On average the planet is warmer than it was a century ago.
Which of the following options correctly describe the different sources of fresh water?
Sea water can be used as a source of water. Surface water is found in lakes, streams, and rivers. Groundwater is found in aquifers.
Solution A has a pH of 6.0, while solution B has a pH of 9.0. Which of the following options correctly describe these two solutions?
Solution A is more acidic than solution B. The [H+] in solution A is 1000 times greater than the [H+] in solution B.
Which of the following statements correctly describe the process by which an ionic compound dissolves in water?
The attraction between the H2O molecules and the ions is stronger than the attraction of the ions for each other. The positive and negative ions dissociate from each other. The positive ions are attracted to the partially negative O atom of the H2O.
Which of the following options correctly describe the changes observed in global temperature over time?
The average global temperature has increased over the same period as atmospheric CO2 levels have increased. The average global temperature of the Earth has increased over the past century.
Which of the following statements correctly describe molar mass?
The molar mass of oxygen is 16.00 g/mol. This means that 1 mole of oxygen atoms has a mass of 16.00 g. The periodic table can be used to calculate the molar mass of any substance. The molar mass of a molecular substance is the mass per mole of its molecules.
Which of the following options correctly interpret the information given? Select all that apply. Molar mass of NO2 = 46.0 g/mol; molar mass of nitrogen = 14.0 g/mol; molar mass of oxygen = 16.0 g/mol
The percentage oxygen in NO2 is equal to 32.046.032.046.0 x 100%. There are 14.0 g of nitrogen in every 46.0 g of NO2. The percentage of nitrogen in NO2 is equal to 30.4%.
Which of the following factors influence the ability of a molecule to act as a greenhouse gas?
The shape of the molecule
Which of the following options correctly describes how an acid produces ions when dissolved in water?
The strong attraction between H2O molecules and the H of the acid causes the acid molecule to break apart.
In what way does the structural formula of a compound differ from its molecular formula?
The structural formula shows the arrangement of atoms and bonds.
Which of the following can be used to determine the heat released by a combustion reaction performed in a calorimeter?
The temperature increase of the calorimeter system
Which of the following options correctly describe the isotope Cr-53,if the element Cr (chromium) has an atomic number of 24?
This isotope contains 29 neutrons in its nucleus. The element contains 24 protons in its nucleus.
Which of the following options correctly describe the expected greenhouse gas activity of CH2Cl2? Select all that apply.
This molecule can undergo bending vibrations that will absorb IR radiation. This molecule will absorb IR radiation and can behave as a greenhouse gas.
Which of the following options correctly describe the electron groups and geometry of the molecule shown?
This molecule is trigonal pyramidal in shape. There are 4 electron groups around the central P atom.
Why is water a liquid a room temperature instead of a gas?
Water has hydrogen bonds between the molecules
Which of the following options correctly expresses the relationship between [OH-] and [H3O+] in solution?
[H+][OH-] = 1 × 10-14
The capacity of a lake or other body of water to resist a decrease in pH when exposed to acidic precipitation or runoff is called its _____ capacity.
acid-neutralizing
SO2, NO2, and CO2 all produce _____ solutions in water. Multiple choice question.
acidic
As [H+] in solution increases, the pH of the solution __
decreases
In any aqueous solution, as [H+] increases, [OH-] _____.
decreases
Which type of water may be considered pure?
distilled water
The process by which atmospheric gases trap and return more than 80% of the heat energy radiated by Earth is called the ______ greenhouse effect, resulting in an increase in average global temperatures.
enhanced
The H+ ions produced by an acid in aqueous solution associate strongly with H2O to form the ______ ion, which has the formula ______.
hydronium; H3O+
Which characteristics pertain to the problem of global warming? i. Possible consequences include altered climate and increased sea level. ii. Heat energy radiated by the earth is captured by atmospheric molecules. iii. Increased skin cancer incidence and damage to radiation sensitive species has been observed. iv. The concentration of stratospheric ozone is declining.
i and ii
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
In a(n) _____ compound electrons are transferred from one atom or group of atoms to another. Conversely, in a(n) _____ compound electrons are shared.
ionic; covalent
One______ of any substance contains Avogadro's number of particles.
mol or mole
The symbol ⇌ used in an equation indicates that a particular reaction _______.
occurs in both the forward and reverse directions at the same time
Match each pair of solutions to the correct description of their relative acidity
pH of A = 3.0; pH of B = 4.0 ;A is 10 times more acidic than B. pH of A = 8.0; pH of B = 4.0;B is 10,000 times more acidic than A pH of A = 6.0; pH of B = 8.0;A is 100 times more acidic than B. pH of A = 10.5; pH of B = 7.5; B is 1000 times more acidic than A
Match each pair of solutions to the correct description of their relative acidity.
pH of A = 3.0; pH of B = 4.0; A is 10 times more acidic than B. pH of A = 8.0; pH of B = 4.0; B is 10,000 times more acidic than A pH of A = 6.0; pH of B = 8.0; A is 100 times more acidic than B. pH of A = 10.5; pH of B = 7.5; B is 1000 times more acidic than A
The general solubility rule "like dissolves like" explains why polar solutes are soluble in ______ solvents and nonpolar solutes are soluble in ______ solvents.
polar; nonpolar
An acid releases H+ ions in water. The H+ ion is a hydrogen atom that has lost its electron, and is therefore often referred to as a(n)_____
proton
Which corresponds to the composition of the ion typically formed by fluorine?
protons - 9 electrons - 10 net charge - 1-
In order to predict if a given molecule can act as a greenhouse gas, we must determine its molecular ________ using the Lewis structure.
shape
The quantity of heat energy that must be absorbed to increase the temperature of 1 gram of a substance by 1°C is called its _____. Multiple choice question.
specific heat
Ocean acidification is correctly described as _____.
the lowering of ocean pH due to increased atmospheric CO2
True or false: Water and ethanol will mix, since they are both polar.
true
A polar covalent bond is created when
two atoms share their bonding electrons unequally.
Electronegativity generally increases _______ on the periodic table, excluding noble gases.
up and to the right
The internationally accepted atomic mass standard is carbon-12 because this isotope
was arbitrarily selected as a convenient standard.
Which is not a consequence of hydrogen bonding between water molecules?
water is colorless and odorless
Ice core data shows that atmospheric CO2 levels _____. Multiple choice question.
were relatively constant from the beginning of the last millennium until around 1800