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Which phrase describes an Al atom?*
What is the number of electrons in an atom that has 20 protons and 17 neutrons?*
The mass of a proton is approximately equal to the mass of*
When a sample of CO2(s) becomes CO2(g), there is a change in*
Which properties are characteristic of Group 2 elements at STP?*
Compared to an atom of C-12, an atom of C-14 has a greater*
Elements that have atoms with stable valence electron configurations in the ground state are found in*
A magnesium atom that loses two electrons becomes a*
An atom of which element has the strongest attraction for the electrons in a bond?*
Which type of matter can not be broken down into simpler substances by a chemical change?*
According to Table F, which substance is most soluble in water?*
Given the equation representing a reaction:
H + H → H2
Which statement describes the energy change in this reaction?*
Which sample of matter is a mixture?*
Paper chromatography can separate the components of a mixture of colored dyes because the components have differences in*
At standard pressure, the boiling point of an unsaturated NaNO3(aq) solution increases when*
Which term identifies a form of energy?*
According to kinetic molecular theory, which statement describes one characteristic of an ideal gas system?*
The temperature of a substance is a measure of the*
A real gas behaves most like an ideal gas at*
A reaction is most likely to occur when the colliding particles have proper orientation and*
At STP, a 12.0-liter sample of CH4(g) has the same total number of molecules as*
At standard pressure, during which physical change does the potential energy decrease?*
Which equation represents a chemical equilibrium?*
The amount of randomness of the atoms in a system is an indication of the*
When a sample of Ca(s) loses 1 mole of electrons in a reaction with a sample of O2(g), the oxygen*
Which reaction occurs at the anode of an electrochemical cell?*
Which substance is an electrolyte?*
In which process does a heavy nucleus split into two lighter nuclei?*
Which process converts mass into energy?*
Which radioisotope is used to determine the age of once-living organisms?*
Which electron configuration represents the electrons in an atom of calcium in an excited state?*
The table below gives the atomic mass and the abundance of the two naturally occurring isotopes of bromine.
Which numerical setup can be used to calculate the atomic mass of the element bromine?*
Given the formulas of two substances:
These diagrams represent substances that have*
What is the chemical formula of titanium(II) oxide?*
Which equation shows conservation of mass and energy for a reaction at 101.3 kPa and 298 K?*
Which two particle diagrams each represent a sample of one substance?
According to Table G, which substance forms an unsaturated solution when 80. grams of the substance are stirred into 100. grams of H2O at 10.°C?*
What is the concentration of AgCl in an aqueous solution that contains 1.2 × 10−3 gram of AgCl in 800. grams of the solution?*
A sample of gas is in a rigid cylinder with a movable piston. The pressure of the gas is kept constant. If the Kelvin temperature of the gas is doubled, the volume of the gas is*
What is the amount of heat required to completely melt a 200.-gram sample of H2O(s) at STP?*
As a 15.1-gram sample of a metal absorbs 48.75 J of heat, its temperature increases 25.0 K. What is the specific heat capacity of the metal?*
Given the formula:
What is a chemical name of this compound?*
Which type of reaction is represented by this equation?*
Atoms of which element react spontaneously with Mg2+(aq)?*
In a titration, 5.0 mL of a 2.0 M NaOH(aq) solution exactly neutralizes 10.0 mL of an HCl(aq) solution. What is the concentration of the HCl(aq) solution?*
Given the equation representing a reaction at equilibrium:
NH3(g) + H2O(ℓ) ⇌ NH4+(aq) + OH−aq)
If an acid is defined as an H+ donor, what is the acid in the forward reaction?*
Compared to a solution with a pH value of 7, a solution with a thousand times greater hydronium ion concentration has a pH value of*
Which Lewis electron-dot diagram represents the bonding in potassium iodide?*
The table below shows properties of two compounds at standard pressure.
Which statement classifies the two compounds?*
Given two balanced equations, each representing a reaction:
Equation 1: 22688Ra →22286Rn + 42He + 4.8 × 108 kJ
Equation 2: C3H8 + 5O2 → 3CO2 + 4H2O + 2.2 × 103 kJ
Which statement compares the energy terms in these two equations?*
Base your answers to questions 51 and 52 on the information below and on your knowledge of chemistry.
The formula below represents a molecule of butanamide.
State the type of chemical bond between a hydrogen atom and the nitrogen atom in the molecule.*
Explain, in terms of charge distribution, why a molecule of butanamide is polar.*
Base your answers to questions 53 and 54 on the information below and on your knowledge of chemistry.
An equilibrium system in a sealed, rigid container is represented by the equation below.
CO(g) + H2O(g) ⇌ CO2(g) + H2(g)
Compare the rate of the forward reaction to the rate of the reverse reaction at equilibrium.*
State the effect on the concentrations of H2O(g) and CO2(g) when more H2(g) is added to the system.*
Base your answers to questions 55 through 58 on the information below and on your knowledge of chemistry.
The table below contains selected information about chlorine and two compounds containing chlorine. One piece of information is missing for each of the substances in the table.
Identify the phase of the chlorine at STP.*
Determine the molar mass for calcium chloride.*
The liquid compound has an empirical formula of CHCl. Write the molecular formula for this compound.*
Explain, in terms of electrons, why the compound containing calcium and chlorine is classified as an ionic compound.*
Base your answers to questions 59 and 60 on the information below and on your knowledge of chemistry.
The equation below represents the reaction between 2-methylpropene and hydrogen chloride gas.
Explain, in terms of chemical bonds, why the hydrocarbon is unsaturated.*
Identify the class of organic compounds to which the product belongs.*
Base your answers to questions 61 through 65 on the information below and on your knowledge of chemistry.
Many scientists made observations of the elements that led to the modern Periodic Table. In 1829, Dobereiner found groups of three elements that have similar properties and called each of these groups a triad. Dobereiner noticed a relationship between the atomic masses of the elements in each triad. Triad 1, shown in the table below, consists of sulfur, selenium, and tellurium. The middle element, selenium, has an atomic mass that is close to the sum of the atomic masses of sulfur and tellurium, divided by 2.
The other triads shown in the table below demonstrate the same mathematical relationship.
Identify the triad that contains a metalloid.*
Explain, in terms of electrons, why the elements in triad 2 have similar chemical properties.*
State the trend in first ionization energy as the elements in triad 3 are considered in order of increasing atomic number.*
Compare the volume of a 100.-gram sample of the first element in triad 4 to the volume of a 100.-gram sample of the third element in triad 4 when both samples are at room temperature.*
Show a numerical setup that demonstrates Dobereiner’s mathematical relationship for triad 2.*
Base your answers to questions 66 through 68 on the information below and on your knowledge of chemistry.
Wood is mainly cellulose, a polymer produced by plants. One use of wood is as a fuel in campfires, fireplaces, and wood furnaces. The molecules of cellulose are long chains of repeating units. Each unit of the chain can be represented as C6H10O5. The balanced equation below represents a reaction that occurs when C6H10O5 is burned in air.
C6H10O5 + 6O2 → 6CO2 + 5H2O + heat
State evidence from the equation that this reaction is exothermic.*
Explain, in terms of substances in the reaction, why the equation represents a chemical change.*
Show a numerical setup for calculating the percent composition by mass of carbon in C6H10O5 (gram-formula mass = 162.1 g/mol).*
Base your answers to questions 69 through 72 on the information below and on your knowledge of chemistry.
Millions of tons of ammonia are produced each year for use as fertilizer to increase food production. Most of the hydrogen needed to produce ammonia comes from methane gas reacting with steam. This reaction, which occurs in a container under controlled conditions, is shown below in unbalanced equation 1.
Equation 1: CH4(g) + H2O(g) + energy → CO(g) + H2(g)
The reaction that produces ammonia is represented by balanced equation 2, shown below. A catalyst can be used to increase the rate of the reaction.
Equation 2: N2(g) + 3H2(g) → 2NH3(g) + energy
A potential energy diagram for equation 2 is shown below.
Balance equation 1 shown below, using the smallest whole-number coefficients.
Explain, in terms of collision theory, why an increase in temperature increases the rate of reaction between methane gas and steam.*
State what is represented by interval A on the potential energy diagram.*
Determine the number of moles of hydrogen gas required to react completely with 50.0 moles of nitrogen gas in the production of ammonia.*
Base your answers to questions 73 through 77 on the information below and on your knowledge of chemistry.
Diethyl ether is used as a laboratory and industrial solvent. The boiling point of diethyl ether at standard pressure is 34.6°C. The equation below represents a reaction that produces diethyl ether.
Identify the element in diethyl ether that allows it to be classified as an organic compound.*
State the number of electrons shared between the carbon atoms in one molecule of the organic reactant.*
State why the reaction is classified as a synthesis reaction.*
Explain, in terms of the strength of intermolecular forces, why the boiling point of diethyl ether at standard pressure is lower than the boiling point of water at standard pressure.*
Draw a structural formula for an isomer of the product that has the same functional group.*
Base your answers to questions 78 through 81 on the information below and on your knowledge of chemistry.
The electrolysis of brine, a concentrated aqueous sodium chloride solution, produces three important industrial chemicals: chlorine gas, hydrogen gas, and sodium hydroxide. The diagram and equation below represent a brine electrolysis cell. Before the battery is connected, the pH value of the brine solution is 7.0.
Explain, in terms of energy, why this cell is an electrolytic cell.*
Explain, in terms of ions, why the aqueous solution in the cell conducts an electric current.*
State the oxidation number of oxygen in the aqueous product.*
Compare the pH value of the solution before the battery is connected to the pH value of the solution after the cell operates for 20 minutes.*
Base your answers to questions 82 through 85 on the information below and on your knowledge of chemistry.
The isotope Rn-222 is produced by the decay of uranium in Earth’s crust. Some of this isotope leaks into basements of homes in areas where the ground is more porous. An atom of Rn-222 decays to an atom of Pb-206 through a series of steps as shown on the graph below.
Determine the number of neutrons in an atom of Pb-214.*
Complete the nuclear equation below for the decay of Po-218 by writing a notation for the missing product.
Determine the fraction of an original sample of Rn-222 that remains unchanged after 7.646 days.*
Explain, in terms of elements, why the decay of Bi-210 is considered a transmutation.*