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The mass of a proton is approximately equal to the mass of*
An orbital of an atom is defined as the most probable location of*
What must occur when an electron in an atom returns from a higher energy state to a lower energy state?*
Which element is a liquid at 305 K and 1.0 atmosphere?*
Which list of elements consists of a metal, a metalloid, and a nonmetal?*
At STP, which physical property of aluminum always remains the same from sample to sample?*
Which statement describes a chemical property of silicon?*
Which diagram represents a mixture of two different molecular forms of the same element?
A compound is broken down by chemical means during*
Which quantities must be conserved in all chemical reactions?*
Which phrase describes the distribution of charge and the polarity of a CH4 molecule?*
What is the charge of the nucleus of an oxygen atom?*
Which ion has no electrons?*
To break a chemical bond, energy must be*
Which Lewis electron-dot diagram represents a nitrogen atom in the ground state?*
What is the most likely electronegativity value for a metallic element?*
Which polyatomic ion has a charge of 3−?*
Every chlorine atom has*
Which substance can not be broken down by a chemical change?*
At standard pressure, which substance becomes less soluble in water as temperature increases from 10.°C to 80.°C?*
Which type of concentration is calculated when the grams of solute is divided by the grams of the solution, and the result is multiplied by 1 000 000?*
Which type of energy is associated with the random motion of atoms and molecules in a sample of air?*
The temperature of a sample of matter is a measure of the*
Which unit is used to express the pressure of a gas?*
Which sample of matter sublimes at room temperature and standard pressure?*
Given the diagram representing a closed system at constant temperature:
Which statement describes this system at equilibrium?*
Which reaction occurs at the cathode in an electrochemical cell?*
Which substance yields H+(aq) as the only positive ion in an aqueous solution?*
Compared to the mass and the penetrating power of an alpha particle, a beta particle has*
During a nuclear reaction, mass is converted into*
An atom in the ground state has two electrons in its first shell and six electrons in its second shell. What is the total number of protons in the nucleus of this atom?*
A bromine atom in an excited state could have an electron configuration of*
The atomic masses and the natural abundances of the two naturally occurring isotopes of lithium are shown in the table below.
Which numerical setup can be used to deter- mine the atomic mass of lithium?*
Element X reacts with chlorine to form an ionic compound that has the formula XCl2. To which group on the Periodic Table could element X belong?*
Which general trend is found in Period 3 as the elements are considered in order of increasing atomic number?*
Given the formula for a compound:
Which molecular formula and empirical formula represent this compound?*
What is the gram-formula mass of (NH4)3PO4?*
In the ground state, which atom has a completely filled valence electron shell?*
Given the formula:
The bond between which two atoms has the greatest degree of polarity?*
Given the diagram representing a heating curve for a substance:
During which time interval is the average kinetic energy of the particles of the substance constant while the potential energy of the particles increases?*
At 50.°C and standard pressure, intermolecular forces of attraction are strongest in a sample of*
At 101.3 kPa and 298 K, what is the total amount of heat released when one mole of aluminum oxide, Al2O3(s), is formed from its elements?*
Given the balanced equation representing a reaction:
2H2O(ℓ) + 571.6 kJ → 2H2(g) + O2(g)
What occurred as a result of this reaction?*
Given the potential energy diagram representing a reversible reaction:
The activation energy for the reverse reaction is represented by*
Which formula represents a molecule of 2-chlorobutane?*
Which formula represents an unsaturated hydrocarbon?*
Which ion is most easily reduced?*
HSO4−(aq) + H2O(ℓ) → H3O+(aq) + SO42−(aq)
According to one acid-base theory, the H2O(ℓ) molecules act as*
Which equation represents an oxidation- reduction reaction?*
Which equation represents natural transmutation?*
What is the mass of KNO3(s) that must dissolve in 100. grams of water to form a saturated solution at 50.°C?*
Base your answers to questions 52 through 55 on the information below.
The reaction between aluminum and an aqueous solution of copper(II) sulfate is represented by the unbalanced equation below.
Al(s) + CuSO4(aq) → Al2(SO4)3(aq) + Cu(s)
Identify the type of chemical reaction represented by the equation.*
Balance the equation below, using the smallest whole-number coefficients.
Explain why the equation represents a chemical change.*
Determine the total mass of Cu produced when 1.08 grams of Al reacts completely with 9.58 grams of CuSO4 to produce 6.85 grams of Al2(SO4)3.*
Base your answers to questions 56 through 59 on the information below.
A total of 1.4 moles of sodium nitrate is dissolved in enough water to make 2.0 liters of an aqueous solution. The gram-formula mass of sodium nitrate is 85 grams per mole.
Write the chemical formula for the solute in the solution.*
Show a numerical setup for calculating the mass of the solute used to make the solution.*
Compare the boiling point of the solution at standard pressure to the boiling point of H2O at standard pressure.*
Determine the molarity of the solution.*
Base your answers to questions 60 through 62 on the information below.
Calcium reacts with water. This reaction is represented by the balanced equation below. The aqueous product of this reaction can be heated to evaporate the water, leaving a white solid, Ca(OH)2(s).
Ca(s) + 2H2O(ℓ) → Ca(OH)2(aq) + H2(g)
Compare the electrical conductivity of the aqueous product in the reaction to the electrical conductivity of the white solid that remains after the water is evaporated from the solution.*
Write the chemical name of the base produced in the reaction.*
State one change in reaction conditions that will increase the rate of the reaction.*
Base your answers to questions 63 through 65 on the information below.
In a titration, 20.0 milliliters of 0.15 M HCl(aq) is exactly neutralized by 18.0 milliliters of KOH(aq).
Complete the equation below for the neutralization reaction by writing the formula of each product.
Compare the number of moles of H+(aq) ions to the number of moles of OH−(aq) ions in the titration mixture when the HCl(aq) is exactly neutralized by the KOH(aq).*
Determine the concentration of the KOH(aq).*
Base your answers to questions 66 through 68 on the information below.
John Dalton, an early scientist, sketched the structure of compounds using his own symbols for the elements known at the time. Dalton’s symbols for four elements and his drawing of potassium aluminum sulfate are represented by the diagram below.
Today, it is known that the chemical formula for potassium aluminum sulfate is KAl(SO4)2•12H2O. It is a hydrated compound because water molecules are included within its crystal structure. There are 12 moles of H2O for every 1 mole of KAl(SO4)2. The compound contains two different positive ions. The gram-formula mass of KAl(SO4)2•12H2O is 474 grams per mole.
Identify one positive ion in the hydrated compound. Your response must include both the chemical symbol and charge of the ion.*
Describe, in terms of composition, one way in which Dalton’s perception of potassium aluminum sulfate differs from what is known today about the compound.*
Show a numerical setup for calculating the percent composition by mass of water in KAl(SO4)2•12H2O.*
Base your answers to questions 69 through 71 on the information below.
At standard pressure, hydrogen peroxide, H2O2, melts at −0.4°C, boils at 151°C, and is very soluble in water. A bottle of aqueous hydrogen peroxide, H2O2(aq), purchased from a pharmacy has a pressure-releasing cap. Aqueous hydrogen peroxide decomposes at room temperature, as represented by the balanced equation below.
2H2O2(aq) → 2H2O(ℓ) + O2(g) + 196.0 kJ
State, in terms of both melting point and boiling point, why H2O2 is a liquid at room temperature.*
State evidence that indicates the decomposition of H2O2(aq) is exothermic.*
Explain why a hydrogen peroxide bottle needs a pressure-releasing cap.*
Base your answers to questions 72 through 75 on the information below.
A student constructs an electrochemical cell during a laboratory investigation. When the switch is closed, electrons flow through the external circuit. The diagram and equation below represent this cell and the reaction that occurs.
State the direction of electron flow through the wire when the switch is closed.*
Write a balanced half-reaction equation for the oxidation that occurs when the switch is closed.*
Determine the number of moles of Al(s) needed to completely react with 9.0 moles of Ni2+(aq) ions.*
State, in terms of energy, why this cell is a voltaic cell.*
Base your answers to questions 76 through 78 on the information below.
The diagram below shows typical pH values found in four parts of the human digestive system. In the small intestine, the enzyme lipase acts as a catalyst, increasing the rate of fat digestion.
Which labeled part of the digestive system has the most acidic environment?*
What is the color of thymol blue at the pH of the small intestine?*
State how the catalyst lipase increases the rate of the fat digestion.*
Base your answers to questions 79 through 81 on the information below.
One type of soap is produced when ethyl stearate and sodium hydroxide react. The soap produced by this reaction is called sodium stearate. The other product of the reaction is ethanol. This reaction is represented by the balanced equation below.
Identify the type of organic reaction used to make soap.*
To which class of organic compounds does ethyl stearate belong?*
Identify the two types of bonds in the compound sodium stearate.*
Base your answers to questions 82 through 85 on the information below.
Nuclear fission has been used to produce electricity. However, nuclear fusion for electricity production is still under development. The notations of some nuclides used in nuclear reactions are shown in the table below.
Compare the atomic masses of nuclides used in fusion to the atomic masses of nuclides used in fission.*
Complete the table below that compares the total number of protons and the total number of neutrons for the hydrogen nuclides used for fusion.
Complete the nuclear equation below for the fission of 23592U by writing the notation of the missing product.
State one potential benefit of using nuclear fusion instead of the current use of nuclear fission to produce electricity.*