AP Chem Ch. 10 AP Questions

A sample of a hard, solid binary compound at room temperature did not conduct electricity as a pure solid but became highly conductive when dissolved in water. Which of the following types of interactions is most likely found between the particles in the substance? A Ionic bonds B Metallic bonds C Covalent bonds D Hydrogen bonds

A Ionic bonds

Ne, HF, C2H6, CH4 Which of the substances listed above has the highest boiling point, and why? A Ne, because its atoms have the largest radius B HF, because its molecules form hydrogen bonds C C2H6 , because each molecule can form multiple hydrogen bonds D CH4 , because its molecules have the greatest London dispersion forces

B HF, because its molecules form hydrogen bonds

Four different liquid compounds in flasks at 20°C are represented above. The table below identifies the compounds. Flask C shows the most particles in the vapor phase. Which of the following is not shown in the model but best helps to explain why flask C must contain pentane? Name Chemical Formula Boiling Point (°C) Pentane CH3CH2CH2CH2CH3 36 Hexane CH3CH2CH2CH2CH2CH3 69 Heptane CH3CH2CH2CH2CH2CH2CH3 98 Octane CH3CH2CH2CH2CH2CH2CH2CH3 126 A The random motion of the particles within the liquids B The relative speeds of the vapor particles in each flask C The strength of the intermolecular forces between the particles in the liquids D The structural formula of the molecules of the liquid and vapor in each flask

C The strength of the intermolecular forces between the particles in the liquids

In the diagram above, which of the labeled arrows identifies hydrogen bonding in water? A B C D

D

In which of the following liquids do the intermolecular forces include dipole-dipole forces? A F2(l) B CH4(l) C CF4(l) D CH2F2(l)

D CH2F2(l)

of F2 , however, HF has a much higher boiling point than F2 has. Which of the following explains how the dispersion-force model of intermolecular attraction does not account for the unusually high boiling point of HF? A F2 F 2 is soluble in water, whereas HF HF is insoluble in water. B The F2 F 2 molecule has a greater mass than the HF HF molecule has. C Liquid F2 F 2 has weak dispersion force attractions between its molecules, whereas liquid HF HF has strong ionic interactions between H+ H + and F− F − ions. D Liquid F2 has weak dispersion force attractions between its molecules, whereas liquid HF has both weak dispersion force attractions and hydrogen bonding interactions between its molecules.

D Liquid F2 has weak dispersion force attractions between its molecules, whereas liquid HF has both weak dispersion force attractions and hydrogen bonding interactions between its molecules

The energy required to dissociate an ionic solid into gaseous ions (lattice energy) for the compounds NaF and MgF2 is shown in the table above. On the basis of Coulomb's law, which of the following best helps to explain the large difference between the lattice energies of NaF and MgF2 ? A The solubility of MgF2 MgF 2 is less than that of NaF NaF . B The electronegativity of Mg Mg is greater than that of Na Na . C The mass of the Mg Mg cation is greater than that of the Na Na cation. D The charge of the Mg cation is larger than that of the Na cation.

D The charge of the Mg cation is larger than that of the Na cation

In solid methane, the forces between neighboring CH4 molecules are best characterized as A ionic bonds B covalent bonds C hydrogen bonds D ion-dipole forces E London (dispersion) forces

E London (dispersion) forces

The boiling points of the elements helium, neon, argon, krypton, and xenon increase in that order. Which of the following statements accounts for this increase? A The London (dispersion) forces increase. B The hydrogen bonding increases. C The dipole-dipole forces increase. D The chemical reactivity increases. E The number of nearest neighbors increases.

A The London (dispersion) forces increase.

Based on the data in the table above, which of the following liquid substances has the weakest intermolecular forces? A C6H6(l) B C2H5OH(l) C CH3OH(l) D C2H6O2(l)

C CH3OH(l)

The particle-level diagram above represents the structure of solid KF. Although the molar mass of KCl is greater than that of KF, the density of KCl is actually less than that of KF. Which of the following representations of the structure of KCl best helps to explain this phenomenon? A The figure presents a particle diagram consisting of 5 small shaded circles, which represent positive ions and 4 large unshaded circles, which represent negative ions. The circles are arranged in 3 rows of 3, alternating between positive and negative ions. Rows 1 and 3 begin with a positive ion, and row 2 begins with a negative ion. There is quite a bit of space between the circles. B The figure presents a particle diagram consisting of 4 shaded circles, which represent positive ions and 5 unshaded circles, which represent negative ions. The circles are all the same size and are arranged in 3 rows of 3, alternating between negative and positive ions. Rows 1 and 3 begin with a negative ion, and row 2 begins with a positive ion. The circles are close together but none of the circles are touching. C The figure presents a particle diagram consisting of 4 large shaded circles, which represent positive ions and 5 small unshaded circles, which represent negative ions. The circles are arranged in 3 rows of 3, alternating between positive and negative ions. Rows 1 and 3 begin with a positive ion, and row 2 begins with a negative ion. The circles are close together but none of the circles are touching. D The figure presents a particle diagram consisting of 6 shaded circles, which represent positive ions and 3 unshaded circles, which represent negative ions. The circles are all the same size and are arranged in 3 rows of 3. Rows 1 and 3 each have 3 positive ions, and row 2 has 3 negative ions. The circles are close together but none of the circles are touching.

A

Based on the data in the table above, which of the following correctly predicts the relative strength of the attraction of Zn2+, Ca2+, and Ba2+ ions to water molecules in a solution, from strongest to weakest, and provides the correct reason? A Zn2+ > Ca2+ > Ba2+ because the smaller ions have a stronger coulombic attraction to water B Zn2+ > Ca2+ > Ba2+ because the smaller ions are more electronegative C Ba2+ > Ca2+ > Zn2+ because the larger ions are more polarizable D Ba2+ > Ca2+ > Zn2+ because the larger ions are less electronegative

A Zn2+ > Ca2+ > Ba2+ because the smaller ions have a stronger coulombic attraction to water

At 298 K and 1 atm, Br2 is a liquid with a high vapor pressure, and Cl2 is a gas. Those observations provide evidence that under the given conditions, the A forces among Br2 molecules are stronger than those among Cl2 molecules B forces among Cl2 molecules are stronger than the Cl−Cl bond C Br−Br bond is stronger than the Cl−Cl bond D Cl−Cl bond is stronger than the Br−Br bond

A forces among Br2 molecules are stronger than those among Cl2 molecules

Copper atoms and zinc atoms have the same atomic radius, 135 picometers. Based on this information, which of the following diagrams best represents an alloy containing only copper and zinc atoms? A The figure presents a particulate-level diagram containing two types of particles: large white particles and small grey particles. The large white particles are arranged in a square lattice. The small grey particles are located throughout this lattice, at every other intersection of four large white particles. B The figure presents a particulate-level diagram containing two types of particles: white particles and grey particles of equal size. The particles are arranged in a diagonal lattice such that each particle is directly adjacent to four others: to the top left, to the top right, to the bottom left, and to the bottom right. About a quarter of the particles are grey. Each grey particle is adjacent only to white particles. C The figure presents a particulate-level diagram containing two types of particles: large negatively charged grey particles and small positively charged white particles. The two types of particles are arranged in a checkerboard pattern, such that each positively charged white particle is adjacent to four negatively charged grey particles, and that each negatively charged grey particle is adjacent to four positively charged white particles. D The figure presents a particulate level diagram containing grey particles arranged in a square lattice.

B

Steel is an alloy consisting of Fe with a small amount of C. Elemental Cr can be added to steel to make the steel less likely to rust; Cr atoms react with oxygen in the air to form a nonreactive layer of chromium oxide on the surface of the steel, preventing the oxidation of underlying Fe atoms. A sample of steel-chromium alloy contains 15 percent Cr by mass. Which of the following diagrams best shows a particle-level view of a surface section and an interior section of the alloy represented below at the left? (The atomic radii of the atoms involved are given in the table below at the right.) Option A. The diagram on the left shows twenty large circles in 4 rows and 5 columns. The circles are not touching each other and are labeled F e. In each space surrounded by 4 large circles is a small circle labeled O. There is also a row of small circles labeled O on top of the first, top, row of large circles. A The diagram on the left shows twenty large circles in 4 rows and 5 columns. The circles are not touching each other and are labeled F e. In each space surrounded by 4 large circles is a small circle labeled O. There is also a row of small circles labeled O on top of the first, top, row of large circles. The diagram on the right is very similar to the diagram on the left. The small circles are labeled C instead of O, and there is no row of small circles on top of the first row of large circles. B The diagram on the left shows twenty large circles in 4 rows and 5 columns. The circles are not touching each other and most are labeled F e. Two large circles in the first, top, row and one large circle in the bottom, fourth, row are labeled C r. There is a row of small circles labeled O on top of the first row of large circles. In some of the spaces surrounded by 4 large circles are small circles labeled either O or C. There are small circles labeled O between the first and second rows of large circles, and there are small circles labeled C between the second and third rows and between the third and fourth rows of large circles. The diagram on the right is very similar to the diagram on the left. One of the large circles labeled C r is in the third row instead of the first row. There are no small circles labeled O, and there is an additional circle labeled C above the top row of large circles. C The diagram on the left shows twenty large circles in 4 rows and 5 columns. The circles are not touching each other, and are labeled F e. In each space surrounded by 4 large circles is a small circle. Most of these small circles are labeled C r, but 2 of them are labeled C. There is also a row of small circles labeled O on top of the first, top, row of large circles. The diagram on the right is identical except there is no row of small circles labeled O on top of the first row of large circles. D The diagram on the left shows twenty large circles in 4 rows and 5 columns. The circles are not touching each other and most are labeled F e. Two large circles in the first, top, row and one large circle in the third row are labeled C r. In some of the spaces surrounded by 4 large circles are small circles labeled either O or C. The small circles labeled O are between the first and second rows of large circles, and the small circles labeled C are between the second and third rows and between the third and fourth rows of large circles. There is also a row of small circles labeled O on top of the first, top, row of large circles. The diagram on the right is very similar to the diagram on the left. One of the large C r circles is in the second row instead of the first row. There is no row of small circles labeled O on top of the first row of large circles. The small circles labeled O are between the first and second rows and between the second and third rows of large circles, and the small circles labeled C are between the first and second rows and between the third and fourth rows of large circles.

B

Steel is an alloy containing Fe atoms and C atoms. Which of the following diagrams best represents the particle-level structure of steel? A The figure presents a particle diagram consisting of 12 large unshaded circles, which represent C atoms and 6 small shaded circles, which represent F e atoms. The large C atoms are arranged in a 3 by 4 array. The small F e atoms are located throughout this lattice, at every intersection of four large C atoms. B The figure presents a particle diagram consisting of 12 large unshaded circles, which represent F e atoms and 6 small shaded circles, which represent C atoms. The large F e atoms are arranged in a 3 by 4 array. The small C atoms are located throughout this lattice, at every intersection of four large F e atoms. C The figure presents a particle diagram consisting of 6 unshaded circles, which represent C atoms and 6 shaded circles, which represent F e atoms. The circles are all the same size and are in a 3 by 4 array, alternating between F e atoms and C atoms. Rows 1 and 3 begin with a F e atom, and row 2 begins with a C atom. D The figure presents a particle diagram consisting of 6 large unshaded circles and 3 small unshaded circles, which represent C atoms, and 6 large shaded circles and 3 small shaded circles, which represent F e atoms. The large C and F e atoms are in a 3 by 4 array, alternating between F e atoms and C atoms. Rows 1 and 3 begin with a F e atom, and row 2 begins with C atom. The small C and F e atoms are located throughout this lattice, at every intersection of four large atoms. The small atoms alternate between C and F e atoms, such that the first row of intersections begins with a C atom, and the second row of intersections begins with a Fe atom.

B

The ionic compounds NaCl and MgS are represented by the diagrams above. Which statement correctly identifies diagram 1 and identifies the compound with the lower melting point, explaining why? A Diagram 1 represents NaCl NaCl ; it has a lower melting point than MgS MgS has because the coulombic attractions between the singly charged Na+ Na + ions and the Cl− Cl − ions in NaCl NaCl are stronger than those between the ions in MgS MgS . B Diagram 1 represents NaCl; it has a lower melting point than MgS because the coulombic attractions between its singly charged Na+ ions and the Cl− Cl − ions are weaker than those between the ions in MgS MgS . C Diagram 1 represents MgS MgS ; it has a lower melting point than NaCl NaCl because the coulombic attractions between its doubly charged Mg2+ Mg 2 + ions and the S2− S 2 − ions are stronger than those between the ions in NaCl NaCl . D Diagram 1 represents MgS MgS ; it has a lower melting point than NaCl NaCl because the coulombic attractions between the doubly charged Mg2+ Mg 2 + ions and the S2− S 2 − ions are weaker than those between the ions in NaCl NaCl

B

Which statement best helps to explain the observation that NH3(l) boils at −28°C, whereas PH3(l) boils at −126°C? A The dispersion forces in NH3 NH 3 are weaker than the dispersion forces in PH3 PH 3 . B The dispersion forces in NH3 NH 3 are stronger than the dipole-dipole forces in PH3 PH 3 . C NH3 NH 3 has hydrogen bonding that is stronger than the dipole-dipole forces in PH3 PH 3 . D NH3 NH 3 has hydrogen bonding that is weaker than the dipole-dipole forces in PH3 PH 3

C

Which of the following correctly indicates whether the solid represented by the particulate model shown above conducts electricity and explains why or why not? A It conducts electricity because it is made of positive and negative ions. B It conducts electricity because it is made of particles of different sizes. C It does not conduct electricity because its ions cannot move freely within the solid. D It does not conduct electricity because there are small spaces between the particles.

C It does not conduct electricity because its ions cannot move freely within the solid

Consider the molecules represented above and the data in the table below. The figure shows a table with 4 columns and 3 rows. The top row contains the column labels, from left to right: column 1, Compound; column 2, Molecular Formula; column 3, Molar Mass (grams per mole); column 4, Boiling Point (degree Celsius). From top to bottom, the data is as follows: Row 2; Compound, Nonane, Molecular Formula, C 9 H 20, Molar Mass, 128, Boiling Point, 151. Row 3; Compound, 2,3,4 trifluoropentane, Molecular Formula, C 5 H 9 F 3, Molar Mass, 126, Boiling Point, 89. Nonane and 2,3,4-trifluoropentane have almost identical molar masses, but nonane has a significantly higher boiling point. Which of the following statements best helps explain this observation? A The C-F bond is easier to break than the C-H bond. B The C-F bond is more polar than the C-H bond. C The carbon chains are longer in nonane than they are in 2,3,4-trifluoropentane. D The carbon chains are farther apart in a sample of nonane than they are in 2,3,4- trifluoropentane.

C The carbon chains are longer in nonane than they are in 2,3,4-trifluoropentane

A student is given a sample of a pure, white crystalline substance. Which of the following would be most useful in providing data to determine if the substance is an ionic compound? A Examining the crystals of the substance under a microscope B Determining the density of the substance C Testing the electrical conductivity of the crystals D Testing the electrical conductivity of an aqueous solution of the substance

D Testing the electrical conductivity of an aqueous solution of the substance