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According to the wave-mechanical model of the atom, an orbital is a region of the most probable location of*
Which particles have approximately the same mass?*
During a flame test, a lithium salt produces a characteristic red flame. This red color is produced when electrons in excited lithium atoms*
Compared to the energy and charge of the electrons in the first shell of a Be atom, the electrons in the second shell of this atom have*
Which quantity can vary among atoms of the same element?*
Which substances have atoms of the same element but different molecular structures?*
An atom that has 13 protons and 15 neutrons is an isotope of the element*
Which elements have the most similar chemical properties?*
Which list includes three types of chemical formulas for organic compounds?*
In a bond between an atom of carbon and an atom of fluorine, the fluorine atom has a*
A sample of CO2(s) and a sample of CO2(g) differ in their*
Which statement defines the temperature of a sample of matter?*
For a chemical reaction, the difference between the potential energy of the products and the potential energy of the reactants is equal to the*
Which equation represents sublimation?*
Which statement describes the particles of an ideal gas, based on the kinetic molecular theory?*
Two grams of potassium chloride are completely dissolved in a sample of water in a beaker. This solution is classified as*
Which compound has the strongest hydrogen bonding between its molecules?*
Powdered sulfur is yellow, and powdered iron is gray. When powdered sulfur and powdered iron are mixed at 20°C, the powdered iron*
An effective collision between reactant particles requires the particles to have the proper*
Which term is defined as a measure of the disorder of a system?*
Which process is used to determine the concen- tration of an acid?*
The compounds CH3OCH3 and CH3CH2OH have different functional groups. Therefore, these compounds have different*
Which term identifies the half-reaction that occurs at the anode of an operating electro- chemical cell?*
During the operation of a voltaic cell, the cell produces*
In which type of chemical reaction are electrons transferred?*
A substance that dissolves in water and produces hydronium ions as the only positive ions in the solution is classified as*
According to one acid-base theory, a base is an*
Which compound is an electrolyte?*
Which term identifies a type of nuclear reaction?*
Which radioisotopes have the same decay mode and have half-lives greater than 1 hour?*
The diagram below represents the bright-line spectra of four elements and a bright-line spectrum produced by a mixture of three of these elements.
Which element is not present in the mixture?*
What is the overall charge of an ion that has 12 protons, 10 electrons, and 14 neutrons?*
As the elements in Period 3 are considered in order of increasing atomic number, there is a general decrease in*
Which electron configuration represents the electrons of a sulfur atom in an excited state?*
Given the word equation:
sodium chlorate → sodium chloride + oxygen
Which type of chemical reaction is represented by this equation?*
Which compound has the highest percent com- position by mass of strontium?*
Given the formula for hydrazine:
How many pairs of electrons are shared between the two nitrogen atoms?*
Which formulas represent one ionic compound and one molecular compound?*
Which Kelvin temperature is equal to 200.°C?*
A 10.0-gram sample of H2O(ℓ) at 23.0°C absorbs 209 joules of heat. What is the final temperature of the H2O(ℓ) sample?*
Given the equation representing a system at equilibrium:
When the concentration of Cl−(aq) is increased, the concentration of Ag+(aq)*
Which particle diagram represents a sample of matter that can not be broken down by chemical means?
Which formula represents an unsaturated hydrocarbon?*
When the pH of a solution is changed from 4 to 3, the hydronium ion concentration of the solution*
Three samples of the same solution are tested, each with a different indicator. All three indicators, bromthymol blue, bromcresol green, and thymol blue, appear blue if the pH of the solution is*
A 10.0-milliliter sample of NaOH(aq) is neutral- ized by 40.0 milliliters of 0.50 M HCl. What is the molarity of the NaOH(aq)?*
Radiation is spontaneously emitted from hydrogen-3 nuclei, but radiation is not spontaneously emitted from hydrogen-1 nuclei or hydrogen-2 nuclei. Which hydrogen nuclei are stable?*
Given the equation representing a nuclear reaction in which X represents a nuclide:
23290Th → 42He + X
Which nuclide is represented by X?*
After decaying for 48 hours, 1/16 of the original mass of a radioisotope sample remains unchanged. What is the half-life of this radioisotope?*
Which balanced equation represents nuclear fusion?*
Base your answers to questions 51 through 53 on the information below and on your knowledge of chemistry.
When magnesium is ignited in air, the magnesium reacts with oxygen and nitrogen. The reaction between magnesium and nitrogen is represented by the unbalanced equation below.
Mg(s) + N2(g) → Mg3N2(s)
Balance the equation below for the reaction between magnesium and nitrogen, using the smallest whole-number coefficients.
In the ground state, which noble gas has atoms with the same electron configuration as a magnesium ion?*
Explain, in terms of electrons, why an atom of the metal in this reaction forms an ion that has a smaller radius than its atom.*
Base your answers to questions 54 through 56 on the information below and on your knowledge of chemistry.
The balanced equation below represents a reaction.
O2(g) + energy → O(g) + O(g)
Identify the type of chemical bond in a molecule of the reactant.*
In the space in your answer booklet, draw a Lewis electron-dot diagram of one oxygen atom.*
Explain, in terms of bonds, why energy is absorbed during this reaction.*
Base your answers to questions 57 through 59 on the information below and on your knowledge of chemistry.
Starting as a solid at −25°C, a sample of H2O is heated at a constant rate until the sample is at 125°C. This heating occurs at standard pressure. The graph below represents the relationship between temperature and heat added to the sample.
Describe what happens to both the potential energy and the average kinetic energy of the molecules in the H2O sample during interval AB.*
Using the graph, determine the total amount of heat added to the sample during interval CD.*
Explain, in terms of heat of fusion and heat of vaporization, why the heat added during interval DE is greater than the heat added during interval BC for this sample of water.*
Base your answers to questions 60 through 62 on the information below and on your knowledge of chemistry.
Cylinder A has a movable piston and contains hydrogen gas. An identical cylinder, B, contains methane gas. The diagram below represents these cylinders and the conditions of pressure, volume, and temperature of the gas in each cylinder.
Compare the total number of gas molecules in cylinder A to the total number of gas molecules in cylinder B.*
State a change in temperature and a change in pressure that will cause the gas in cylinder A to behave more like an ideal gas.*
In the space in your answer booklet, show a numerical setup for calculating the volume of the gas in cylinder B at STP.*
Base your answers to questions 63 through 65 on the information below and on your knowledge of chemistry.
There are several isomers of C6H14. The formulas and boiling points for two of these isomers are given in the table below.
Identify the homologous series to which these isomers belong.*
Write the empirical formula for isomer 1.*
Explain, in terms of intermolecular forces, why isomer 2 boils at a lower temperature than isomer 1.*
Base your answers to questions 66 through 69 on the information below and on your knowledge of chemistry.
Before atomic numbers were known, Mendeleev developed a classification system for the 63 elements known in 1872, using oxide formulas and atomic masses. He used an R in the oxide formulas to represent any element in each group. The atomic mass was listed in parentheses after the symbol of each element. A modified version of Mendeleev’s classification system is shown in the table below.
Identify one characteristic used by Mendeleev to develop his classification system of the elements.*
Based on Mendeleev’s oxide formula, what is the number of electrons lost by each atom of the elements in Group III?*
Based on Table J, identify the least active metal listed in Group I on Mendeleev’s table.*
Explain, in terms of chemical reactivity, why the elements in Group 18 on the modern Periodic Table were not identified by Mendeleev at that time.*
Base your answers to questions 70 through 73 on the information below and on your knowledge of chemistry.
In a laboratory apparatus, a sample of lead(II) oxide reacts with hydrogen gas at high temperature. The products of this reaction are liquid lead and water vapor. As the reaction proceeds, water vapor and excess hydrogen gas leave the glass tube. The diagram and balanced equation below represent this reaction.
Determine the change in oxidation number for the hydrogen that reacts.*
Write a balanced half-reaction equation for the reduction of the Pb2+ ions in this reaction.*
Explain why the reaction that occurs in this glass tube can not reach equilibrium.*
State one change in reaction conditions, other than adding a catalyst, that would cause the rate of this reaction to increase.*
Base your answers to questions 74 through 77 on the information below and on your knowledge of chemistry.
In the late 19th century, the Hall-Herroult process was invented as an inexpensive way to produce aluminum. In this process, Al2O3(ℓ) extracted from bauxite is dissolved in Na3AlF6(ℓ) in a graphite-lined tank, as shown in the diagram below. The products are carbon dioxide and molten aluminum metal.
Compare the chemical properties of a 300.-kilogram sample of Al2O3(ℓ) with the chemical properties of a 600.-kilogram sample of Al2O3(ℓ).*
Write the chemical name for the liquid compound dissolved in the Na3AlF6(ℓ).*
What is the melting point of the substance that collects at the bottom of the tank?*
Compare the density of the Al(ℓ) with the density of the mixture of Al2O3(ℓ) and Na3AlF6(ℓ).*
Base your answers to questions 78 through 80 on the information below and on your knowledge of chemistry.
One process used to manufacture sulfuric acid is called the contact process. One step in this process, the reaction between sulfur dioxide and oxygen, is represented by the forward reaction in the system at equilibrium shown below.
2SO2(g) + O2(g) ⇌ 2SO3(g) + 394 kJ
A mixture of platinum and vanadium(V) oxide may be used as a catalyst for this reaction. The sulfur trioxide produced is then used to make sulfuric acid.
Determine the amount of energy released when 1.00 mole of sulfur trioxide is produced.*
Write the chemical formula for vanadium(V) oxide.*
On the labeled axes in your answer booklet, complete the potential energy diagram for the forward reaction represented by this equation.*
Base your answers to questions 81 and 82 on the information below and on your knowledge of chemistry.
Two very stable compounds, Freon-12 and Freon-14, are used as liquid refrigerants. A Freon-12 molecule consists of one carbon atom, two chlorine atoms, and two fluorine atoms. A Freon-14 molecule consists of one carbon atom and four fluorine atoms.
In the space in your answer booklet, draw a structural formula for Freon-12.*
To which class of organic compounds do Freon-12 and Freon-14 belong?*
Base your answers to questions 83 through 85 on the information below and on your knowledge of chemistry.
Chemical concepts are applied in candy making. A recipe for making lollipops is shown below.
Explain, in terms of the polarity of sugar molecules, why the sugar dissolves in water.*
Determine the concentration, expressed as percent by mass, of the sugar dissolved in the mixture produced in step 1.*
Explain, in terms of the concentration of sugar molecules, why the boiling point of the mixture in step 3 increases as water evaporates from the mixture.*