AP Chemistry DPS Midterm Review Wynne

A neutral element with one unpaired electron in a p orbital will most likely have which of the following ion charges when an ion is formed?

-5 or +1

A solution is prepared by adding 16.0g of CH3OH to 90.0g of H20. The mole fraction of CH3OH in this solution is closest to which of the following?

0.1

The melting point of MgO is higher than that of NaF. Explainations for this observation include which o the following 1. Mg2+ is more positively charged than Na+ 2. O2- is more negatively charged than F- 3. The only O2- ion is smaller than F- ion

1 and 2 only

Which bonds are formed by a carbon with sp2 hybridization

1 pi bond and 3 sigma bonds

Which of the following is the electron configuration that shows an element is an excited state?

1s2 2S2 2P6 3S2 3P5 4S1

A 34.1 g sample of a copper(II) chloride hydrate was heated to drive off the water. The remaining anhydrous sample was 26.9g. Which of the following is the number of waters of hydration in the hydrate?

2

Which of the following are correcte resonance structures of SO3

2,3, and 4 only

In 1.00 mol of potassium zirconium sulfate trihydrate, K4Zr(SO4)4 3 H20, there are

2.41 x 10^24 potassium atoms

Ordinary bleach is 5.25% NaOCl by mass with a density of 1.11 g/mL. How many grams of NaOCl are in 50.0 mL of bleach?

2.91

Use the mass spectrograph below to determine the relative atomic mass of cadmium

20.18 amu

How many resonance forms can be written for the nitrate ion NO3-

3

How many sigma and pi bonds are in a molecule of ethane HCCH

3 sigma and 2 pi

The first ionization energy for Na is 495 kJ/mol. The BEST estimate for sodium's second ionization energy would be:

4560 jj/mol

In thye lewis structure of Formica acid HCOOH, how many bonding pairs and lone pairs of electrons are present?

5 bonding 4 lone

How many sigma bonds does propane C3H4 have

6

Naturally occurring chlorine has two principle isotopes: Cl-35 and Cl-37. Which of the following is the relative abundance of the two isotopes of chlorine?

77.5% for Cl-35 and 22.5% for Cl-37

Consider the following successive ionization energies in kJ/mol. E1=580 kJ/mol E2= 1815 kJ/mol E3= 2740 kJ/mol E4= 11600 kJ/mol E5= 14842 kJ/mol Which of the following elements could have this successive ionization energy data?

Al

Which of the following ionic compounds is likely to have the highest melting point

AlN

The O-N-O bond angles in the nitrate ion, NO3-, are best described as being

All 120

Based on coulombic forces, which of the following will have the highest melting point?

Aluminum

Consider an alloy contains CU and one other element. Which of the following would correctly describe an allow containing Cu?

An would form a substitution all allow with it due to their similar radii

The red curve in the figure below shows the variation in potential energy of the system as a function of distance between the two atoms as they move together to form a bond. The atoms are approaching from infinite separation towards eachother. which of the following best accounts for the change in the potential energy of the system going from point A ot point B

As the atoms get closer together, their nuclei begin to repel one another

Which of the following compounds has a non-zero dipole moment

AsH3

The mass spectrum of the element Sb is most likely represented by which of the following?

B

Which molecule has no permanent dipole moment?

BCl3

Which of the following best explains the relative positioning and intensity of the 2s peaks in the following spectra

Be has a greater nuclear charge than Li and more Electrons in the 2s orbital.

The nitrate ion NO20 may be represented by two major resonance forms. The lengths of the nitrogen to oxygen bonds in this ion are expected to be

Between the lengths of a nitrogen to oxygen single bond and a nitrogen to oxygen double bond

Which of the following elements is represented by this graph? (Multiply the mass/charge by abundance and add together the sum should be the amu of the element)

Boron

Which molecule contains three sigma bonds and two pi bonds

C2H2

Which molecules represented below contain carbon with sp2 hybridization

C2H2Cl2

Which of the following elements would be BESt to mix with Fe in the formation of an interstitial alloy, if Fe has an atomic radius of 156 pm?

C: 67 pm

Upon combustion, a 30.0 g sample of a compound containing only carbon, hydrogen, and oxygen produces 44.0g of carbon dioxide and 18.0g of water. Which of the following is the empirical formula of the compound?

CH2O

Pi bonding occurs in each of the following species except

CH4

Which of the following has the greatest percent by mass of carbon

CH4

On the basis of the information above, which of the following arranges the binary compounds in order of increasing bond polarity

CH4<SiCl4<SF4

In the table below, an element and its electronegativity are missing. Which of the following provides the correct element with the orrect electronegativity?

CL 3.16

For which species is the electron pair geometry around the central atom of the lewis dot structure the same as the geometry of the atoms?

CO2

Of the following compounds, which is the most ionic?

CaCl2

The table below shows the first six ionization energies for a second period element. Which of the following identifies the element and provides the best explanation?

Carbon because it has four valence electrons.

The radius of S2- ions is 184 pm, while the radius of Cl- ion is 181 pm. Which fo the following accounts for why this is true?

Cl has a greater effective nuclear charge than S2-

In metallic bonding, what is the dominant form of attraction between the lattice of positive ions and the sea of delocalized electrons?

Electrostatic

Which statement describes the energy changes that occur as bonds are broke and formed during a chemical reaction?

Energy is absorbed when bonds are broken and energy is released when bonds are formed.

Which pair of atoms has the most polar bond

H-Cl

Which fo the following has the bonds arranged in order of decreasing polarity?

H-F > N-F > F-F

The least polar bond is found in a molecule of

HI

The energy required to dissociate an ionic solid into gaseous ions (lattice energy) for the compounds NaF and MgF2 is shown in the table below. on the basis of Coulomb's law, which of the following best helps to explain the large difference between the lattice energy of NaF and MgF2?

He charge of the Mg cation is larger than that of the Na cation.

The elements I and Te have similar average atomic masses. A sample that was believed to be a mixture of I and Te was run through a mass spectrometer, resulting in the data below. If all of the following statements are true, which one would be the best basis for concluding that the sample was pure Te?

I consists of only one naturally occurring isotope with 74 neutrons whereas Te has more than one isotope.

Which of the following ranks the following elements (Si, N, In, Ne) in order of increasing first ionization energy?

In<Si<N<Ne

According to the VSEPR model, the progressive decrease in the bond angles in the series of molecules CH4, NH3, and H2O is best accounted for by the

Increasing number of unshared pairs of electrons

Properties of two elements on the same row of the periodic table are given below. Which of the following correctly predicts the type of bond that would form between an atom of each element and provides and accurate explanation?

Ionic since the electronegativity is greater than 1.5.

Two pure elements react to form a compound. One element is an alkali metal, X, and the other element is a halogen, Z. Which of the following is the most valid scientific claim that can be made about the compound?

It contains ionic bonds.

Which of the following correctly indicates whether the solid represents by the particulate model shown opposite conducts electricity and explains why or why not ?

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

Looking at the spectra for Na and K below, which of the following would best explain the difference in binding energy for 3s electrons?

K has a greater nuclear charge than Na.

A student has a 1g sample of each of the following compounds: NaCl, KBr, and KCl. Which of the following lists the samples in order of increasing number of moles in the sample?

Kbr < KCl < NaCl

Which of the following alkali metals would have the strongest Coulombic forces, leading to the highest melting point when paired with the corresponding halogen in the same period?

Li

A compound is found to contain 1.32 moles of Li, 0.66 moles of Se, and 2.64 moles of O2. Which of the following is the empirical formula of the compound?

Li2SeO4

Which of the following statements BEST explains the difference in melting points between MgO (2852) and NaF (1819)

Magnesium and oxygen have higher charge values and therefore have greater Coulombic attraction.

A solid substance is an excellent conductor of electricity. The chemical bonds in this substance are most likely

Metallic because the valence electrons are mobile.

Which of the following best explains why metals are good conductors of electricity?

Metallic bonding can be described as an electron sea with mobile valence electrons

Shown in the diagram are the electronic structures of lithium and calcium ions. The melting temperature of lithium is 181 while calcium's is 842. Based on their electronic structures of the atoms and the stream they of their metallic bonds, eplxian this difference in melting temperature.

Metallic bonds are weaker in lithium as there are fewer valence electrons, so less thermal energy is needed to break up the metal lattice.

The mass spectrum of a sample of pure element is shown below. Based on the data, the peak at 26 amu represents an isotope of which of the following elements

Mg with 14 neutrons

The lattice energy of a salt is related to the energy required to separate the ions. For which of the following pairs of ions is the energy that is required to separate the ions largest? (Assume that the distance between the ions in each pair is equal to the sum of the ionic radii.) (largest charges and smallest elements)

Mg2+ + O2

MgCl2 is a white crystalline solid with a melting point of 714ºC. Which o the following is most likely to have similar properties

MgF2, since F and Cl both have seven valence electrons.

According to the information in the table shown, a 1.00 g sample of which of the following contains the greatest mass of oxygen

MgO

A student obtains a sample of pure solid compound. In addition to avogardo's number, which of the following must the student know in order to determine how many molecules are in the sample.

Molar mass of the compound, mass of the sample

Which of the following elements has the mass spectrum represented below

Molybdenum (lines average to about 95.6)

A sample of nitrogen- and oxygen-containing molecules is decomposed into its elements. It is found to contain 14.0g of nitrogen and 40.0 of oxygen. Which of the following is the empirical formula of the compound?

N2O5

In which species is resonance most useful in explaining the observed bond lengths

NF3

Which of the following compounds contains both ionic and covalent bonds?

NH4Cl

Which species has a lewis diagram and structure most like that of the carbonate ion, CO3 2-

NO3-

Based on the data in the table opposite, which of the following statements provides the best prediction for the boiling point of NaCl?

NaCL will have a lower boiling point that's NaF because the coulomb ic attractions are weaker in NaCl than NaF

The lattice energies of four ionic compounds W, X, Y and Z are measured. The energies are found to be -922, -769, and -699 respectively. The four ionic compounds are NaCl, Naf, KBr, KCl. which of the following compounds could be identified as Compound X based on the lattice energies given?

NaCl

Which of the following is the best description of electrical conduction in a solid metal?

Negatively charged elementary particles flow through a lattice of positive ions

Which element could be represented by the complete PES spectrum below?

Nitrogen

Consider the simulated PES spectrum below, showing the energy required to remove a 1s electron from an isolated nitrogen atom (red) and an isolated oxygen atom (blue). Which of the following BEST accounts for the peak in the nitrogen atom being to the right of the peak for the oxygen atom?

Nitrogen atoms have a smaller nuclear charge than do oxygen atoms.

Which species has a different number of pi bonds than the others

O3

If A represents the central atom in which molecule is the F-A-F angle the smallest?

OF2

The first ionization energy for nitrogen is 1420 kJ/mol and oxygen is 314 kJ/mol. Which of the following is the best explanation for this data?

Oxygen has more electron-electron repulsion in its P orbital.

Which of the following sets of elements and/or ions contain species that are i so electric (same number of electrons)?

P3-,S2-,Ar

Which molecule is correctly matched with its shape as predicted by VSEPR theory

PCL3 trigonal pyramidal

Which of the following arranges the atoms in order of increasing radius?

Rb+<Kr<Br-

Given the photoelectron spectra below for phosphorus and sulfur which of the following best explains why the 2p peak for S is further to the left than the 2p peak for P, but the 3p peak for S is further to the right than the 3p peak for P

S has a greater effective nuclear charge than P and the 3p sub level in S has greater electron reclusion's than in P

In which species can we describe the central atom has having sp2 hybridization

SO2

Which of the following atoms would be BEST substitute for Cu in the formation of subsitituional alloy, if the atomic radius of Cu is 145

Sn: 145

The hybridization of carbon atoms in the molecule represented below can be described as

Sp3

Which of the following can be inferred from the diagram opposite that shows the dependence of potential energy on the internuclear distance between two atoms

The atoms form a bond with a bond length of 75 pm (bond length is the lowest part of the graphs x value)

The potential energy of a system of two atoms as a function of their internuclear distance is shown in the diagram opposite. which of the following is true regarding the forces between the atoms when their internuclear distance is x?

The attractive and repulsive forces are balanced, so the atoms will maintain their average internuclear distance x.

Which of the following scientific claims about the bond in molecular compound HF is most likely to be true?

The bond is highly polar

Al is a relatively malleable metal. When Al forms an alloy with Cu, however, it becomes less malleable. Which of the following explanations accounts for this observation?

The covalent bond between Al and Cu is much stronger than te metallic bonding within Al.

Metals are typically shiny and electrically conductive, while ionic solids are dull and electrically insulating. which feature of metals is responsible for this difference?

The delocalized electrons.

The image on the left is solid NaCl and the one on the right is solid MgO. As you can see, they both have the same lattice arrangement but MgO has a higher melting point. Which of the following primarily accounts for this difference in melting points?

The electrostatic attraction between Mg 2+ and O2- ions is stronger.

Which of the following statements best describes the first ionization energies of sodium compared to potassium?

The first ionization energy for sodium is greater than for potassium due to lower nuclear shielding.

Which of the following graphs correctly shows the relationship between potential energy and internuclear separation for two hydrogen atoms

The graph dips down below the dotted line

Which Lewis dot structure is the most likely representation for the sulfate ion, So3 2-

The one with all single bonds and a lone pair on S

Which of the following atoms would form a solid metal with the highest melting point

The one with the largest atom and the greatest amount of valence electrons.

The particle level diagram opposite 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 representation of the structure best helps to explain this phenomenon?

The spaced out one with larger atoms of Cl.

Consider the following table showing the melting and boiling points of three of the alkali metals along with their specific gravities.

The valence electrons in the metallic lattice are farther from the nuclei so they do not bind the atoms as tightly to eachother. As a result less thermal energy is needed to disrupt the solid lattice or to overcome the attractive forces between liquid atoms.

On the basis of VSEPR theory, what geometry is predicted for the central sulfur atom in SOCl2?

Trigonal Pyramidal

Which of the following is the best description of delocalized electrons in metallic bonding?

Valence electrons that can move freely between metal ions.

The potential energy as a function of the internuclear distance for there diatomic molecules, X2, Y2, and Z2, is shown in the graph opposite. Based on the data in the graph, which of the following correctly identifies the diatomic molecules?

X2= H2 Y2=N2 (triple bond) Z2=O2 (double bond)