chemistry final
The pressure, in atm, exerted by 1.85 mol of an ideal gas placed in a 3.00 L container at 35.0°C is given by which of the following expressions?
(1.85)(.0821)(308)/3.00 atm
A 360. mg sample of aspirin, C9H8O4, (molar mass 180. g), is dissolved in enough water to produce 200. mL of solution. What is the molarity of aspirin in a 50. mL sample of this solution?
0.0100 M
A flask contains 0.25 mole of SO2(g), 0.50 mole of CH4(g), and 0.50 mole of O2(g). The total pressure of the gases in the flask is 800 mm Hg. What is the partial pressure of the SO2(g) in the flask?
160 mm Hg
A sealed vessel contains 0.200 mol of oxygen gas, 0.100 mol of nitrogen gas, and 0.200 mol of argon gas. The total pressure of the gas mixture is 5.00 atm. The partial pressure of the argon is
2.00 atm
Based on periodic trends and the data in the table above, which of the following are the most probable values of the atomic radius and the first ionization energy for potassium, respectively?
242 pm, 419 kJ/mol
A 2 L sample of N2(g) and a 1 L sample of Ar(g), each originally at 1 atm and 0°C, are combined in a 1 L tank. If the temperature is held constant, what is the total pressure of the gases in the tank?
3 atm
If the absorbance of the mixture is 0.20 at 453 nm, how many moles of Fe3+(aq) were present in the 100. mL sample? (Assume that any volume change due to adding the KSCN(s) is negligible.)
4 × 10−6 mol
Which of the following is the most likely cause for the increase in pressure observed in the container as the reaction reaches equilibrium?
An increase in the number of molecules, which increases the frequency of collisions with the walls of the container
Which of the following properties generally decreases across the periodic table from sodium to chlorine?
Atomic radius
Atoms of Mg combine with atoms of F to form a compound. Atoms of which of the following elements combine with atoms of F in the same ratio?
Ba
Has the highest electronegativity
Br
A 23.0g sample of a compound contains 12.0g of C, 3.0g of H, and 8.0g of O. Which of the following is the empirical formula of the compound?
C2H6O
Is the LEAST soluble in water
CH3CH2CH2CH3
On the basis of the information above, which of the following arranges the binary compounds in order of increasing bond polarity?
CH4 < SiCl4 < SF4
The photoelectron spectra of the 1s electrons of two isoelectronic species, Ca2+ and Ar, are shown above. Which of the following correctly identifies the species associated with peak X and provides a valid justification?
Ca2+, because its nucleus has two more protons than the nucleus of Ar has
Has the largest atomic radius
Cs
Has the lowest first-ionization energy
Cs
Which of the following best helps to account for the fact that the F- ion is smaller than the O2- ion?
F- has a larger nuclear charge than O2- has.
Which of the following diagrams best represents the AgNO3 solution before the reaction occurs?
H2 ions face NO3- while O ions face Ag+. The two molecules are separate.
Has two lone pairs of electrons
H2O
Of the following molecules, which has the largest dipole moment?
HF
Which of the following complete Lewis diagrams represents a molecule containing a bond angle that is closest to 120°
HHCCOHH
A 0.5 mol sample of He(g) and a 0.5 mol sample of Ne(g) are placed separately in two 10.0 L rigid containers at 25°C. Each container has a pinhole opening. Which of the gases, He(g) or Ne(g), will escape faster through the pinhole and why?
He(g) will escape faster because the He(g) atoms are moving at a higher average speed than the Ne(g) atoms.
The percentage of silver in a solid sample is determined gravimetrically by converting the silver to Ag+(aq) and precipitating it as silver chloride. Failure to do which of the following could cause errors in the analysis? I. Account for the mass of the weighing paper when determining the mass of the sample II. Measure the temperature during the precipitation reaction III.Wash the precipitate IV. Heat the AgCl precipitate to constant mass
I, III, and IV
The diagram above shows two resonance structures for a molecule of C6H6. The phenomenon shown in the diagram best supports which of the following claims about the bonding in C6H
In the C6H6C6H6 molecule, all the bonds between the carbon atoms have the same length.
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 represented by the particulate model shown above conducts electricity and explains why or why not?
It does not conduct electricity because its ions cannot move freely within the solid.
What is the identity of the metal chloride?
KCl
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.)
Mg2+(g) and O2−(g)
According to the information in the table above, a 1.00 g sample of which of the following contains the greatest mass of oxygen?
MgO
Which of the following elements has the largest first ionization energy?
N
Has molecules with a pyramidal shape
NH3(g)
The effective nuclear charge experienced by the outermost electron of Na is different than the effective nuclear charge experienced by the outermost electron of Ne. This difference best accounts for which of the following?
Na has a lower first ionization energy than Ne.
The photoelectron spectra above show the energy required to remove a 1s electron from a nitrogen atom and from an oxygen atom. Which of the following statements best accounts for the peak in the upper spectrum being to the right of the peak in the lower spectrum?
Nitrogen atoms have a smaller nuclear charge than oxygen atoms.
The diagram above represents the photoelectric effect for a metal. When the metal surface is exposed to light with increasing frequency and energy of photons, electrons first begin to be ejected from the metal when the energy of the photons is
Orange
Of the following single bonds, which is the LEAST polar?
O—F
A sample containing atoms of C and F was analyzed using x-ray photoelectron spectroscopy. The portion of the spectrum showing the 1s peaks for atoms of the two elements is shown above. Which of the following correctly identifies the 1s peak for the F atoms and provides an appropriate explanation?
Peak X, because F has a greater nuclear charge than C has.
How many protons, neutrons, and electrons are in an 56/26 Fe atom?
Protons:26 Neutrons: 30 Electrons:26
The diagram above represents the absorption spectrum for a pure molecular substance. Which of the following correctly indicates the type of transition observed for the substance in each of the regions of the absorption spectrum?
Region X- Electronic transition Region Y- Molecular vibration Region Z- Molecular rotation
A compound contains 30. percent sulfur and 70. percent fluorine by mass. The empirical formula of the compound is
SF4
Is a polar molecule
SO2
Is best represented by two or more resonance forms
SO2
Three substances were studied in the laboratory, and the data in the table above were collected. Based on the data, which of the following shows the type of bonding in each substance?
Substance X Network covalent Substance Y Metallic Substance Z Ionic
In which flask do the molecules have the greatest average speed?
T=50 C P=.5 ATM
The mass spectrum of element X is presented in the diagram above. Based on the spectrum, which of the following can be concluded about element X?
The atomic mass of X is between 90 and 92.
Which of the following correctly compares periodic properties of two elements and provides an accurate explanation for that difference?
The atomic radius of Cl is smaller than that of S because Cl has a larger nuclear charge than S does.
Which of the following scientific claims about the bond in the molecular compound HF is most likely to be true?
The bond is highly polar.
Which of the following scientific claims about the bond in the molecular compound HF is most likely to be true? A
The bond is highly polar.
The elements C and Se have the same electronegativity value, 2.55. Which of the following claims about the compound that forms from C and Se is most likely to be true?
The carbon-to-selenium bond is nonpolar covalent.
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 ?
The charge of the MgMg cation is larger than that of the NaNa cation.
After completing an experiment to determine gravimetrically the percentage of water in a hydrate, a student reported a value of 38 percent. The correct value for the percentage of water in the hydrate is 51 percent. Which of the following is the most likely explanation for this difference?
The dehydrated sample absorbed moisture after heating.
When a sample of oxygen gas in a closed container of constant volume is heated until its absolute temperature is doubled, which of the following is also doubled?
The pressure of the gas
A sample of a solid labeled as NaCl may be impure. A student analyzes the sample and determines that it contains 75 percent chlorine by mass. Pure NaCl(s) contains 61 percent chlorine by mass. Which of the following statements is consistent with the data?
The sample contains NaCl(s) and LiCl(s).
The table above shows the first ionization energy and atomic radius of several elements. Which of the following best helps to explain the deviation of the first ionization energy of oxygen from the overall trend?
There is repulsion between paired electrons in oxygen's 2p orbitals.
In a paper chromatography experiment, a sample of a pigment is separated into two components, X and Y, as shown in the figure above. The surface of the paper is moderately polar. What can be concluded about X and Y based on the experimental results?
Y is more polar than X.
The mass spectrum of an average sample of a pure element is shown in the figure above. Which of the following is the identity of the element?
Zr
A certain crystalline substance that has a low melting point does not conduct electricity in solution or when melted. This substance is likely to be
a molecular solid
Of the following, the best explanation for the fact that most gases are easily compressed is that the molecules in a gas
are relatively far apart
At standard temperature and pressure, a 0.50 mol sample of H2 gas and a separate 1.0 mol sample of O2 gas have the same
average molecular kinetic energy
Lewis electron-dot diagrams for CO2 and SO2 are given above. The molecular geometry and polarity of the two substances are
different because S has a greater number of electron domains (regions of electron density) surrounding it than C has
A particle-level diagram of a metallic element is shown above. Typically, metals are both malleable and ductile. The best explanation for these properties is that the electrons involved in bonding among metal atoms are
equally shared and form nondirectional bonds
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
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?
picture with even amounts of copper and zinc
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?
small protons and larger electrons. Mixed together.
Which of the following Lewis diagrams best represents the bonding in the N2O molecule, considering formal charges
triple bond and single bond
