chem final exam compilation
What are the values of ΔS for the water, the surroundings, and the universe for the evaporation of water from an open pan at 25°C?
+ - +
When 2.00 kJ of energy is transferred as heat to nitrogen in a cylinder fitted with a piston with an external pressure of 2.00 atm, the nitrogen gas expands from 2.00 to 5.00 L. What is the change in internal energy of this system?
+1.39 kJ
Calculate the standard entropy of vaporization of ethanol at its boiling point, 352 K. The standard molar enthalpy of vaporization of ethanol at its boiling point is 40.5 kJ/mol.
+115 J/mol·K
The temperature of 2.00 mol Ne(g) is increased from 25°C to 200°C at constant pressure. Assuming the heat capacity of Ne is 20.8 J/K·mol, calculate the change in the entropy of neon. Assume ideal gas behavior.
+19.2 J/K
Calculate the standard reaction enthalpy for the following chemical equation. CH4 (g) + H2O (g) → CO (g) + 3H2 (g) Use the following thermochemical equations to solve for the change in enthalpy. 2H2 (g) + CO (g) → CH3OH (l) ΔH° = -128.3 kJ/mol 2CH4 (g) + O2 (g) → 2CH3OH (l) ΔH° = -328.1 kJ/mol 2H2 (g) + O2 (g) → 2H2O (g) ΔH° = -483.6 kJ/mol
+206.1 kJ/mol
When 4.00 kJ of energy is transferred as heat to nitrogen in a cylinder fitted with a piston at an external pressure of 3.00 atm, the nitrogen gas expands from 1.00 L to 4.00 L against this constant pressure. What is ΔU for the process? Note: 1 L*atm = 0.1013 kJ.
+3.09 kJ
a reaction is spontaneous when delta G is (+, -)
-
For a given reaction, if delta H is (negative/positive/either) and delta S is (negative/positive/either), then the value of ∆G◦rxn will always be negative, regardless of the tem- perature.
- +
Automobile airbags contain solid sodium azide, NaN3, that reacts to produce nitrogen gas when heated, thus inflating the bag. 2NaN3(s)⟶2Na(s)+3N2(g) Calculate the value of work, w, for the system if 19.4 g NaN3 reacts completely at 1.00 atm and 22 °C.
-1.10 x 10^3
Calculate the enthalpy change for the following chemical equation. 2SO2(g) + O2(g) → 2SO3(g) Use the following thermochemical data to solve for the change in enthalpy. ΔHf for SO2(g) = -16.9 kJ/mol ΔHf for SO3(g) = -21.9 kJ/mol
-10.0 kJ/mol rxn
Calculate the standard enthalpy change for the following chemical equation. 2HCl (g) + F2 (g) → 2HF (l) + Cl2 (g) Use the following thermochemical equations to solve for the change in enthalpy. 4HCl (g) + O2 (g) → 2H2O (l) + 2Cl2 (g) ΔH° = -202.4 kJ/mol rxn ½ H2 (g) + ½ F2 (g) → HF (l) ΔH° = -600.0 kJ/mol rxn H2 (g) + ½ O2 (g) → H2O (l) ΔH° = -285.8 kJ/mol rxn
-1015.4 kJ/mol rxn
Nitric acid can be manufactured in a multi-step process, during which nitric oxide is oxidized to create nitrogen dioxide. 2NO (g) + O2 (g) → 2NO2 (g) Calculate the standard reaction enthalpy for the above reaction using the following thermodynamic data. N2 (g) + O2 (g) → 2NO (g) ∆H˚1 = 180.5 kJ/molrxn N2 (g) + 2O2 (g) → 2NO2 (g) ∆H˚2 = 66.4 kJ/molrxn
-114.1 kJ/mol rxn
Using the bond energy data provided, calculate ΔH for the following reaction: H2 (g) + Cl2 (g) → 2HCl (g) Bond Bond Energy (kJ/mol) H‒H 436 Cl‒Cl 242 H‒Cl 432
-186 kJ/mol
The enthalpy of fusion of H2O (s) at its normal melting point is 6.01 kJ/mol. What is the entropy change for freezing 1 mole of water at this temperature?
-22.0 J/mol·K
What is the entropy change for the following chemical reaction at at 25°C? C2H2 (g) + 2H2 (g) → C2H6 (g) What is the enthalpy change for the chemical reaction in question 20? Find the standard reaction free energy for the chemical reaction in question 20 Assuming ΔH°rxn and ΔS°rxn are unaffected by temperature changes, find the temperature at which ΔG° is zero for the chemical reaction in question 20.
-232.7 J/mol·K -311.41 kJ/mol -242.03 kJ/mol 1338 K
Ammonia (NH3) gives windex and cat urine its odor. It has a ΔH°vap of 23.35 kJ/mol and a ΔS°vap of 97.43 J/mol·K. What is the normal boiling point of ammonia?
-33.3°C
The standard molar enthalpy of formation of NH3 (g) is -46.11 kJ/mol. What is the standard molar internal energy of formation of NH3 (g)?
-43.63 kJ/mol
A system gains 642 kJ of heat, resulting in a change in internal energy of the system equal to +166 kJ. How much work is done? Is work done on or by the system?
-476 kJ done by
A 1.00 g sample of n-hexane (C6H14) undergoes complete combustion with excess O2 in a bomb calorimeter. The temperature of the 1502 g of water surrounding the bomb rises from 22.64°C to 29.30°C. The heat capacity of the hardware component of the calorimeter (everything that is not water) is 4042 J/°C. What is ΔU for the combustion of n-C6H14? One mole of n-C6H14 is 86.1 g. The specific heat of water is 4.184 J/g·°C.
-5.92 x 103 kJ/mol
When 0.485 g of compound X is burned completely in a bomb calorimeter containing 3000 g of water, a temperature rise of 0.285°C is observed. What is ΔU of the reaction for the combustion of compound X? The hardware component of the calorimeter has a heat capacity of 3.81 kJ/°C. The specific heat of water is 4.184 J/g·°C, and the MW of X is 56.0 g/mol.
-538 kJ/mol
Calculate the standard enthalpy change for the following chemical equation. 4FeO (s) + O2 (g) → 2Fe2O3 (s) Use the following thermochemical equations to solve for the change in enthalpy. Fe (s) + ½ O2 (g) → FeO (s) ΔH = -269 kJ/mol 2Fe (s) + 3/2 O2 (g) → Fe2O3 (s) ΔH = -825 kJ/mol
-574 kJ/mol
For a certain reaction at constant pressure, the change in internal energy is -52 kJ. In addition, the system does 46 kJ of expansion work. What is ΔH for this process?
-6 kJ
What is the value of work when a piston of volume 0.2 L expands against an external pressure of 200 kPa to a volume of 3.4 L?
-640 J
Consider the following chemical reaction. Calculate ΔG° for the reaction at 298 K. CO (g) + Cl2 (g) → COCl2 (g)
-73.3 kJ/mol
A system does 586 kJ of work and loses 241 kJ of heat to the surroundings. What is the change in internal energy of the system?
-827 kJ
The diameter of the electron density of an atom is roughly...
.1-.5 nm
Calculate the formal charge on N in the molecule NH3.
0
How many double bonds are present in the 'best' resonance structure of the phosphate ion?
1
How many lone pairs of electrons are on nitrogen in NF3?
1
How many values of mℓ are allowed for an electron in a 2s subshell?
1
How many total bonds and lone pairs exist in the Lewis structure for chlorine fluoride (ClF)?
1, 6
Which sub shell is designated by each set of quantum numbers? 1. n=2, l=1 2. n=5, l=4 3. n=4, l=0 4. n=3, l=1
1. 2p 2. 5g 3. 4s 4. 3p
How many electrons in an atom could have these sets of quantum numbers? 1. n=2 2.n=5, l=0 3. n=7, l=3, ml=-1
1. 8 2. 2 3. 2
What are the chemical symbols for the following electron configurations? 1. 1s2 2s2 2p3 2. 1s3 2s2 2p6 3s2 3p6 4s2 3d10 4p6 3. 1s2 2s2 2p6 3s2 3p6 4. 1s2 2s2 2p6 3s2 3p3
1. N 2. Kr 3. Ar 4. P
In 1 sec, a 60 W bulb emits 11 J of energy in the form of infrared radiation (heat) of a corresponding wavelength of 1850 nm. How many photons of infrared radiation does the lamp generate in 1 sec?
1.02 x 10^20
A photon has a frequency of 223 MHz. What is the energy of this photon?
1.48 x .10^-25
Microwave ovens emit microwave energy with a wavelength of 12.1 cm. What is the energy of exactly one photon of this microwave radiation?
1.66 x 10 ^-24 J
Calculate the energy for one mole of photons (an einstein) for light absorbed at 685 nm
1.75 x 10^5 J
Calculate the energy of a photon emitted when an electron in a hydrogen atom undergoes a transition from n=3 to n=1.
1.94 x 10^-18
A sample of gas occupies a volume of 72.5 mL. As it expands, it does 122.2 J of work on its surroundings at a constant pressure of 783 Torr. What is the final volume of the gas?
1243 mL
What is the effective nuclear charge experienced by the 2p and 3p electrons of a chlorine atom, respectively?
15, 7
When an electron beam strikes a block of copper, x-rays of frequency 1.97 x 1019 Hz are emitted. What is the wavelength of these x-rays?
15.2 pm
How many p electrons does Se (atomic number 34) possess?
16
What mass of liquid ethanol (C2H5OH) must be burned to supply 500 kJ of heat? The standard enthalpy of combustion of ethanol at 298 K is -1368 kJ/mol.
16.8 g
Calculate the standard reaction entropy for the decomposition of 1 mol calcite to carbon dioxide gas and solid calcium oxide at 25°C. CaCO3 (s) → CO2 (g) + CaO (s) Substances & their S CaO (s) = 39.75 CO2 (g) = 213.74 CaCO3 (s) = 92.9
160.6 J/mol*K
The P2‒ anion has how many total electrons and how many valence electrons respectively?
17, 7
The electron configuration for the Mn atom is...
1s2 2s2 2p6 3s2 3p6 4s2 3d5
How many resonance structures can be drawn for N2O? Disregard any structure with formal charges other than 0, +1, and -1.
2
How many unshared electrons and bonding electrons exist around the central atom in ozone (O3)?
2, 6
Burning 1 mol of methane in oxygen to form CO2 (g) and H2O (g) produces 803 kJ of energy. How much energy is produced when 3 mol of methane is burned?
2409 kJ
What total number of valence electrons should appear in the dot formula for the chlorate ion ClO3‒?
26
Which of the following chemical reactions exhibit a positive ΔS? Select all of the correct answers. 2H20 (L) + O2 (G) --> H2O2(L) 2H2O (G) --> 2H2 (G) + O2 (G) H2O (G) --> H2O (L) 3O2 (G) --> 2O3 (G)
2H2O (G) --> 2H2 (G) + O2 (G)
Which one of the following reactions has a positive entropy change? BF3 (g) + NH3 (g) --> F3BNH3 (s) H2O (g) --> H2O (l) 2NH4NO3 (s) --> 2N2 (g) + 4H2O (g) + O2 (g 2SO2 (g) + O2 (g) --> 2SO3 (g)
2NH4NO3 (s) --> 2N2 (g) + 4H2O (g) + O2 (g)
How many subshells are there in the shell with n=3?
3
The carbonate ion (CO32-) has how many resonance configurations?
3
What is the bond order of the C‒C bond in acetylene (ethyne, C2H2)?
3
In the n=3 level... How many sub levels? How many orbitals? How many electrons?
3 9 18
A system releases 900 J of heat to the surroundings (27°C). What is ΔS of the surroundings?
3 J/K
How many total bonds and lone pairs exist in the Lewis structure for boron trichloride (BCl3)?
3, 9
If a photon's wavelength is 663 µm, what is its energy?
3.00 x 10^-22
A 200 nm photon has ______ times the energy of a 700 nm photon.
3.5
Sodium vapor lamps, used for public lighting, emit yellow light of a wavelength of 570 nm. How much energy is emitted by an excited sodium atom when it generates a photon?
3.5 x 10^-19 J
Calculate the average S‒F bond energy in SF6 using the following ΔHf values: SF6 (g) = -1209 kJ/mol S (g) = 279 kJ/mol F (g) = 79 kJ/mol
327 kJ/mol bonds
Calculate the normal boiling point of chloroform given that the standard entropy and enthalpy of vaporization of chloroform is 93.7 J/mol·K and 31.4 kJ/mol, respectively.
335 K
Consider the following vaporization reaction. Br2 (l) → Br2 (g) At a certain pressure, ΔH° = 34 kJ/mol and ΔS° = 0.098 kJ/mol·K. What is the lowest temperature at which this process is spontaneous?
347 K
How many orbitals are in the n=2 shell?
4
Light from hydrogen can be emitted at the wavelength of 486.0 nm. What is the energy of one photon of light?
4.09 x 10^-19
What is the change in entropy (∆S) for the heating of 20.0 grams of methanol (CH3OH, liquid) from 34◦C to 62◦C?
4.42 J/K
How much work must be done on a system to decrease its volume from 15.0 L to 6.0 L by exerting a constant pressure of 5.0 atm?
4.56 kJ
A certain shade of blue has frequency of 7.32 x 10^14 Hz. What is the energy of exactly one photon of this light?
4.85 x 10^-19
Light with a frequency of 7.30 x 1014 Hz lies in the violet region of the visible spectrum. What is the wavelength of this frequency of light?
411 nm
Consider the sodium vapor lamps described in question 13. How much energy is emitted by 45.8 mg of sodium atoms emitting light at this wavelength? Assume each sodium atom emits one photon.
420 J
Use the Rydberg formula for atomic hydrogen to calculate the wavelength of the photon emitted in the transition of an electron from n=4 to n=2. What is the name given to the spectroscope series to which the transition described in question 3 belongs? In what region of light will the photons emitted in question 3 lie?
486 nm Balmer series visible blue light
The three quantum numbers for an electron in a hydrogen atom in a certain state are n=4, ℓ=2, and mℓ=1. The electron is located in what type of orbital?
4d
For which H-atom wavefunction are you most likely to find the electron farthest from the nucleus?
4p
How many sub shells are in the n=5 shell?
5
How many values of the quantum number ℓ are possible when n=5?
5
The wavelength of some green light is 530.0 nm. What is the frequency of this green light?
5.66 x 10^14 hz
Carbon emits photons at 745 nm when exposed to blackbody radiation. How much energy would be obtained if 44g of carbon were irradiated? Assume each carbon atom emits one photon.
5.9 x 10^5 J
Consider the following specific heat capacities: H2O (s) = 2.09 J/g·°C H2O (l) = 4.18 J/g·°C H2O (g) = 2.03 J/g·°C The heat of fusion for water is 334 J/g and its heat of vaporization is 2260 J/g. Calculate the amount of heat required to convert 93 g of ice at -36°C completely to liquid water at 35°C.
52 kJ
Consider the following chemical equation: C3H8 (g) + 5O2 (g) → 3CO2 (g) + 4H2O (l) ΔH = -2220 kJ/mol rxn How much thermal energy is given off when 11.0 g of propane gas (C3H8) is burned at constant pressure?
555 kJ
Consider the following unbalanced equation. What is the standard free energy for the reaction of 7.2 moles of Al2O3(s) at 298K? Al2O3 (s) + CO (g) → Al (s) + CO2 (g)
5800 kJ
How many s electrons does P (atomic number 15) possess?
6
A 100 W electric heater (1 W = 1 J/s) operates for 11 min to heat the gas in a cylinder. At the same time, the gas expands from 1 L to 6 L against a constant atmospheric pressure of 3.527 atm. What is the change in internal energy of the gas?
64.21 kJ
For this problem, you will have to look up ΔHf° and the S° values from a table. Estimate the minimum temperature at which magnetite can be reduced to iron by graphite. Fe3O4 (s) + 2C (s, graphite) → 2CO2 (g) + 3Fe (s)
670°C
The specific heat for liquid argon and gaseous argon is 25.0 J/mol·°C and 20.8 J/mol·°C, respectively. The enthalpy of vaporization of argon is 6506 J/mol. How much energy is required to convert 1 mole of liquid Ar from 5°C below its boiling point to 1 mole of gaseous Ar at 5°C above its boiling point?
6735 J
In the Aufbau order of occupancy of electronic energy levels, the level occupied just after 5p is...
6s
How many values of mℓ are allowed for an electron in a 5f subshell?
7
What is the frequency of light with a wavelength of 4.0 x 10-7 m?
7.5 x 10^14
What is the maximum number of electrons that can have the quantum number n=2 in an atom?
8
Assume n1 and n2 are two adjacent energy levels of an atom. The emission of radiation with the longest wavelength would occur for which two values of n1 and n2?
8,7
Carbon monoxide reacts with oxygen to form carbon dioxide by the following reaction: 2CO(g) + O2(g) → 2CO2(g) ΔH for this reaction is -135.28 kcal. How much heat would be released if 12.0 moles of carbon monoxide reacted with sufficient oxygen to produce carbon dioxide? Use only the information provided in this question.
812 kcal
The specific heats and densities of several materials are given below: Steel .118 (Specific Heat) 7 (density) Calculate the change in temperature produced by the addition of 1 kcal of heat to 100 g of steel.
84.7°C
Find the standard entropy change for the formation reaction of CO (g) at 298 K. What is the standard free energy change for the chemical reaction in question 26?
89.36 J/mol·K -137.16 kJ/mol
Rocket fuel would be useless if its oxidation is not spontaneous. A chemist exploring potential fuels for use in space considered using vaporized aluminum chloride. What is the coefficient of O2 (g) in the following balanced chemical equation that contains only whole numbered coefficients (i.e. no fractions)? AlCl3 (g) + O2 (g) → Al2O3 (s) + ClO (g) The below table contains thermodynamic data for the chemical reaction in question 28 at 2000 K. What is ΔGrxn at 2000 K? Consider the reaction in questions 28 and 29. Would this choice of reactants make a good rocket fuel?
9 +700 kJ/mol rxn No. G is positive
It takes light with a wavelength of 212 nm to break the N‒H bond in ammonia. What energy is required per photon to break this bond? What is the N‒H bond strength in terms of kJ per mole?
9.4 x 10^-22 kJ/photon; 565 kJ/mol
A piece of metal with a mass of 22 g at 92 °C is placed in a calorimeter containing 53.7 g of water at 21 °C. The final temperature of the mixture is 55.3 °C. What is the specific heat capacity of the metal? Assume that there is no energy lost to the surroundings.
9.5 J g-1 °C-1
If a system has 3.50×102 kcal of work done to it, and releases 5.00 × 102 kJ of heat into its surroundings, what is the change in internal energy of the system?
9.64 x 10^2 kJ
A particular metal has a work function of 1.05 eV. A light is shined onto this metal with a corresponding wavelength of 324 nm. What is the maximum velocity of the photoelectrons produced? (Hint: 1eV = 1.6022 x 10-19 J, mass of an electron = 9.11 x 10-31 kg)
9.89 x 10^5 m/s
The graph below shows the radial distribution plots for the 1s wavefunctions for H and He+. Which plot (A or B) is the 1s wavefunction for the He+ ion?
A
a trigonal bipyramidal electronic geometry and seesaw molecular geometry
A central atom is surrounded by four chlorine atoms. Which of the following combinations is possible?
The dye that absorbs at 530 nm.
A chemist has synthesized two new dyes based on the molecular structure of plant-based dyes. The lowest energy absorption line for the first dye is light in the visible region at 530 nm. The lowest energy absorption line for the second dye is light in the visible region at 645 nm. Based on this evidence, which molecule has the larger HOMO-LUMO gap?
four, zero, four
A mole with a tetrahedral geometry has _____ regions of high electron density around the central atom. These molecules have central atoms with ______ lone pairs and _______ atoms bonded to them.
He2
According to molecular orbital theory, which of the following is NOT predicted to exist? He2 He2+ He2- He
the overlap of the corresponding atomic orbitals leads to destructive interference.
An antibonding orbital is formed when...
Which of the following would be expected to have the highest first ionization energy? Si, Xe, Ar, Cl, Na
Ar
If the following crystallize in the same type of structure, which has the lowest lattice energy? BaO CaO SrS SrO BaS
BaS
polar nonpolar
BeCl2 polar or nonpolar bonds? polar or nonpolar molecule?
Which of the following atoms has the largest radius? F, Br, N, Cl
Br
more, the C-F bonds are more polar than the C-I bonds
CHF3 is (less, more) polar than CHI3 because...
Consider the following processes. Which entropy will increase as the process proceeds from left to right? Select all of the correct answers H20 (L) --> H20 (S) CaCO3 (S) --> CaO (S) + CO2 (G) NaCl (s) --> Na+ (aq) + Cl- (aq)
CaCO3 (S) --> CaO (S) + CO2 (G) NaCl (s) --> Na+ (aq) + Cl- (aq)
Name the compound CaBr2.
Calcium Bromide
Name the compound CaC2O4.
Calcium Oxalate
Which of the following is the best representation of the individual components of the compound calcium sulfide?
Ca²⁺, S²⁻
polar molecule, polar bonds
Classify polarity of the molecule PBr3
180
Consider a 3-atom molecule A-B-A for which B has a total of only four valence electrons - enough to make two bonds. Predict the A-B-A bond angle.
paramagnetic, 2
Consider the molecule B2 (explored above in question #4). What is the magnetism and number of unpaired electrons in B2?
Determine the element of lowest atomic number that contains a complete d subshell in the ground state.
Cu
Write an equation that represents the second ionization energy of copper.
Cu+(g) --> Cu2+(g) + e-
bent or angular
Determine the molecular geometry of the ion NO2-.
1, 1, 0, 1
Draw the Lewis structure for NO2-. How many single bonds, double bonds, triple bonds, and unshared pairs of electrons are on the central atom, in that order, when considering a single contributing structure (ignoring the averaging effects of resonance)?
An element E has the electronic configuration [Ne] 3s2 3p1. Write the formula of its compound with sulfate.
E₂(SO₄)₃
H2 burning in O2 to form H2O (l) is an example of a system where the entropy of the universe decreases.
False
True/False: All entropies of fusion are negative.
False
True/False: For a given transfer of energy, a greater change in entropy occurs when the temperature is high.
False, because as temperature decreases there is a greater change in entropy.
Consider the elements lithium, oxygen, fluorine, and neon. Based on their position in the periodic table, which element would you expect to have the GREATEST tendency to attract a shared pair of electrons?
Fluorine
What form does N2 take at the standard state?
Gas
Which do you predict to have the strongest C‒N bond? NHCH2 HCN NH2CH3 All are equal.
HCN
4 outer atoms 2 lone pairs
How many outer atoms and lone pairs are present in a molecule with a square planar shape?
trigonal planar t-shaped bent (about 120) linear bent (about 109) see saw square pyrimadal square planar
If the symbol X represents a central atom, Y represents outer atoms, and Z represents lone pairs on the central atom. Classify each molecule according to shape. X Y3 Z X Y3 Z2 X Y2 Z X Y2 Z3 Z Y2 Z2 X Y4 Z X Y5 Z X Y4 Z2
carbon is also involved in a pi bond.
In a new compound, it is found that the central carbon atom is sp2 hybridized. This implies that...
120 180
In the bond... H2C=C=CH2 What is the bond angle of H-C-H? What about the C=C=C angle?
H: 1s, C: sp2
In the molecule, C2H4, what are the atomic orbitals that participate in forming the sigma bond between the C and H atoms?
Which of the following statements concerning the first law of thermodynamics is/are true? Select all of the correct answers. Internal energy lost by a system is always gained by the surroundings. The universe is an isolated system. The internal energy of the universe is always increasing.
Internal energy lost by a system is always gained by the surroundings. The universe is an isolated system.
non polar
Is CCl4 polar or non polar?
Yes
Is IF4- non-polar?
An element E has the electronic configuration 1s2 2s2 2p4. What is the formula of its compound with lithium?
Li₂E
Microwave radiation vs. UV radiation Which has a longer wavelength? Which has a greater frequency? Which has greater energy?
Microwave UV UV
What information is needed to determine the orientation of an orbital?
Ml
Which of the following elements would be expected to have the highest electronegativity? Al P Na He C N
N
more, shorter, higher
N2 has a bond order of 3 and O2 has a bond order of 2. Based on this information, choose the response that best completes the following sentence: N2 is (less, more) stable than O2, and has a (larger, shorter) bond length and a (higher, lower) bond energy.
Which of the following substances have ΔHf° = 0? Select all of the correct answers. HCl (aq) Na (s) F2 (g) C (s, diamond) HCl (g) C (s, graphite)
Na F2 C
Using what you know about periodic trends, rank the following atoms in terms of decreasing atomic radius. Mg, O, F, N, Na
Na, Mg, N, O, F
Give the formula for sodium nitrate.
NaNO₃
Which substance has the lower molar entropy? Kr (g) at 298 k and 1 atm Ne (g) at 298 k and 1 atm they are the same there is no way to know
Ne (g) at 298 k and 1 atm
Write an equation that represents the second ionization energy of nickel.
Ni+(g) --> Ni2+(g) + e-
What does a formation reaction produce?
One mole of a substance from elements in their standard state
Which bond is most polar? I-Cl P-Cl P-I Cl-Cl
P-Cl
Which of the following compounds contains exactly one unshared pair of valence electrons? PH3 C2H4 H2S SiH4
PH₃
Tetrahedral Trigonal pyramidal
Phosphorus trichloride, PCl3, is commonly used in the chemical industry as a source of phosphorus in various reactions. Indicate the electron pair geometry and the molecular geometry of the PCl3 molecule. Electron pair geometry? Molecular geometry?
At a constant volume, what is internal energy equal to?
Q
For which of the following elements would the size of the neutral atom (atomic radius) be the largest? Sr, Rb, Na, Ca
Rb
Blue light vs. Red light Which has longer wavelength? Which has a greater frequency? Which has the greater energy?
Red Blue Blue
Arrange from longest to shortest wavelength. Green light, X ray photon, red photon, high frequency UV radiation, low frequency UV radiation
Red photon Green light low frequency UV radiation high frequency UV radiation x ray photon
Which of the following bonds will be the most polar? C-N Cl-O S-F C-H
S-F
square pyramidal
Shape of ClF5?
seesaw
Shape of SF4?
tetrahedral
Shape of SiH4?
An atom of which element, moving at 240 m/s, would possess a de Broglie wavelength of 1.40 x 10‒11 m?
Sn
Why do the elements at the bottom of the periodic table have lower ionization energies than their group/family partners at the top of the periodic table?
The effective nuclear charge is essentially constant moving down a group/family but the valence shells get farther from their nuclei.
25%, 75%
The sp3 hybridization has what percent s character and what percent p character respectively?
A system had 150 kJ of work done on it and its internal energy increased by 60 kJ. How much energy did the system gain or lose as heat?
The system lost 90 kJ of energy as heat.
Why is it harder to remove an electron from fluorine than from carbon? To put it another way, why are the valence electrons of fluorine more strongly bonded than those of carbon?
The valence electrons of both fluorine and carbon are found at about the same distance from their respective nuclei, but the greater positive charge of the fluorine nucleus attracts its valence electrons more strongly.
C8H9NO2
This is the condensed structural formula for acetaminophen, the active ingredient in the over-the-counter medication Tylenol. What is the molecular formula?
sp
What hybridization would you expect for C in ethyne (C2H2)?
sp3
What hybridization would you expect for Se when it is found in SeO42-?
octahedral
What is the electronic geometry of IF4-?
1
What is the expected bond order for the diatomic species B2?
C4 H10 O
What is the formula?
trigonal planar
What is the geometry around the left-most carbon in the molecule CH2CHCH3?
square planar
What is the molecular geometry of IF4-?
trigonal planar
What is the shape (molecular geometry) of COCl2?
square planar
What is the shape?
tetrahedral
What is the shape?
1, 2, and 3
Which of the following are important contributions that MO theory makes to chemistry? 1. The ability to use MO theory with a computer to calculate the minimum energy geometry of a molecule. 2. The ability to predict the energy at which a molecule will absorb light. 3. The ability to predict whether or not a molecule should be paramagnetic or diamagnetic.
sp3 trigonal pyrimdal
Which of the following combinations of hybridization and molecular geometry is possible? sp3, trigonal pyrimadal sp2, linear sp3d, octahedral sp2, tetrahedral
SF4
Which of the following has bond angles of 90°, 120°, and 180°? ICl4- PF6- SF4 IF5 XeF4
O3
Which of the following has bond angles slightly LESS than 120°?
SF4
Which of the following is a polar molecule? SF4 CO2 CCl4 SO3 XeF2
HCl
Which of the following molecules has the largest dipole moment? H2 HCl F2 HI
BF3
Which of the following molecules is nonpolar? NF3 H2O BF3 SO2 CH3Br
Aufbau Principle, Hund's Rule, and Pauli Exclusion Principle
Which of the following must be observed when filling a molecular orbital energy diagram? Aufbau Principle, Conservation of Matter and Energy, and Planck's Law, Hund's Rule, Pauli Exclusion Principle, Dalton's Law
NO3-
Which of the following species possesses a delocalized bond? H2O NO3- NCl3 H2S
CF4 is a polar molecule.
Which of the following statements about polarity is FALSE? CF4 is a polar molecule. Polar molecules must have a net dipole moment. Lone (unshared) pairs of electrons on the central atom play an important role in influencing polar Linear molecules can be polar Dipole moments can "cancel," giving a net non-polar molecule.
1 and 2
Which of the following statements concerning molecular orbital theory is true? 1. Bonding orbitals are lower in energy than their corresponding anti-bonding orbitals. 2. If a molecule has an odd number of electrons, then it is paramagenetic. 3. The MO diagrams for O2, F2, Ne2 are NOT filled using the Aufbau principle.
2
Which of the following statements concerning molecular orbital theory is/are true? 1. Bonding orbitals are equal in energy to their corresponding anti-bonding orbitals. 2. Adding electrons to anti-bonding orbitals destabilizes molecules. 3. Unlike when we fill atomic orbitals, we DON'T use Hund's Rule to fill molecular orbitals.
The molecule has a single bond.
Which of the following statements is true about a molecule with a bond order of one? The molecule has a single bond. The molecule has no electrons in antibonding orbitals. The molecule is as stable as molecules with bond orders of two and three. Two side-by-side p orbitals combine to form pi bond and pi antibond orbitals; therefore, the bond order is 1.
B
Which of the three Lewis structures is the most important for the fulminate ion (CNO-)? Select all of the correct answers.
BH4 is a trigonal planar shape. Trigonal planar molecules have three regions of high electron density around the central atom.
Which of these is true? BH4 is a trigonal planar shape. NH3 has a trigonal planar shape. Molecules with three outer atoms always have a trigonal planar shape. Trigonal planar molecules have three regions of high electron density around the central atom.
C-F
Which pair of bonded atoms has the largest dipole moment? C-N C-Cl C-F C-O
less stable; H2+ has one less electron in bonding orbitals
Will H2+ be more or less stable than H2 and why?
At a constant volume, is work or heat zero?
Work
Let X be a hypothetical element. Which of the following would be the largest? X - X X 2+ X 2- X +
X ²⁻
Can work and heat both be positive at the same time?
Yes
Will a jump from n=1 to n=3 be absorption or emission?
absorption
The de Broglie equation was important for a number of reasons, not least of which was that it demonstrated that _______.
all objects have a wavelength. however, in the case of macroscopic objects, these wavelengths are so small that they can be ignored
The ground state electron configuration of a neutral silver atom is [Kr] 5s1 4d10 instead of [Kr] 5s2 4d9. This observation can be explained (theoretically) by the fact that...
an enhanced stability is associated with filled sets of equivalent orbitals
polar non polar polar
are the following molecules polar or non-polar? H2O BCl3 BrF3
when H is - and S is +, when is the reaction spontaneous?
at all T
when H is + and S is +, when is the reaction spontaneous?
at high T
when H is - and S is -, when is the reaction spontaneous?
at low T
The existence of quantized energy levels in an atom can be inferred from...
atomic spectral lines
The transition metals are elements with partially filled...
d subshells
The conditions for a specific exothermic re- action are such that it is currently non- spontaneous. Which of the following changes to the conditions will likely make the reaction spontaneous? 1. increase the temperature 2. the reaction spontaneity, in this case, cannot be changed with temperature 3. decrease the temperature
decrease the temperature
Would a jump from n=2 to n=1 be emission or absorption?
emission
Is the formation of bonds exothermic or endothermic?
exothermic; it releases energy (delta H is negative)
(Extensive/Intensive) properties depend on the amount of material present
extensive
Classify each as a state or path function. heat energy distance traveled work enthalpy
heat P energy S distance traveled P work P enthalpy S
The electronegativity of nonmetals is relatively __________ as compared to the electronegativity of metals.
high
the more massive the object, the (lower, higher) the entropy
higher
With fusion, will entropy increase or decrease?
increase
Generally speaking, in the periodic table, electronegativity (decreases, increases) when moving from left to right and (decreases, increases) when moving from top to bottom of the periodic table.
increases, decreases
Arrange the following from lowest to highest frequency. infrared radiation, gamma ray radiation, short wavelength X-rays, blue light, long wavelength X-rays
infrared radiation blue light long wavelength X rays short wavelength X rays gamma ray radiation
Iron metal will react with oxygen gas to form a variety of iron oxides. This oxidation reaction is typically referred to as the iron "rusting". The fact that this reaction is spontaneous at room temperature tells you that 1. the 2nd law of thermodynamics has been violated 2. iron oxides have a higher standard en- tropy compared to oxygen and iron 3. iron oxides have a positive enthalpy of formation 4. iron oxides have a negative Gibbs energy of formation
iron oxides have a negative Gibbs energy of formation
If the products of a reaction have higher energy than the reactants, then the reaction...
is endothermic
As an atom's radius decreases, what happens to ionization energy?
its ionization energy increases.
What information is needed to determine the general shape of an orbital?
l
What information is needed to determine the energy of an electron in a many-electron atom? Select all that apply.
l and n
If ml = 4, what can you say about l?
l is greater than or equal to 4
What are the possible magnetic quantum numbers (m𝓁) associated with each indicated value of 𝓁? l = 2
ml = -2, -1, 0, 1, 2
How do you find delta N?
moles of product - moles of reactants
are solutions more or less disordered than pure substances?
more
What information is most important in determining the size of an orbital?
n
What does each quantum number tell you?
n - distance from the nucleus/energy level l - shape ml - orientation ms - direction of spin
Which quantum number tells you orbital, subshell, and shell? What are each of these things?
n - shell l - subshell ml - orbital
If l=2, what can you deduce about n?
n is greater than 2
An electron in a 3d orbital could have which of the following quantum numbers?
n=3, l=2, ml=0
When ΔG is (+ or -), a process will proceed spontaneously and is referred to as (endergonic or exergonic).
negative, exergonic
If a process is carried out at constant pressure and the volume of the system decreases, then ΔV is _________and the work is __________.
negative, positive
when H is + and S is -, when is the reaction spontaneous?
never
A particular metal has a work function of 3.05 eV. A light is shined onto this metal with a corresponding wavelength of 524 nm. What is the maximum velocity of the photoelectrons produced? (Hint: 1eV = 1.6022 x 10-19 J, mass of an electron = 9.11 x 10-31 kg)
no photoelectrons are produced
When a sugar cube dissolves in a cup of coffee (an endothermic process), entropy changes of the sugar plus water, the surroundings, and the universe respectively are... - - - + + + + - + - + + none of these
none of these
Which of the following is the valence electronic structure for a halogen?
ns2 np5
Identify the generic outer electron configuration for the noble gases.
ns^2 np^6
polar
polar or nonpolar?
A phosphorous‒chlorine bond would be expected to be...
polar, with the chlorine end having a partial negative charge.
If a change is endothermic, is delta H positive or negative?
positive
Max Planck's theory averted the so called "UV Catastrophe" of classical mechanics. Which of the following best describes how Planck's theory avoided the "UV Catastrophe"?
radiation given off by blackbody radiators can only be emitted in quantized amounts
What is the correct order of increasing frequency? UV radiation, visible light, radio waves, infrared radiation
radio waves, infrared radiation, visible light, UV radiation
trigonal bipyramidal
shape of PCl5?
Which of the following lists phases in order of increasing entropy?
solid, liquid, gas
trigonal planar symmetry
sp2 hybrid orbitals have...
Which element is predicted to have the ground-state electron configuration shown below? [Ne] 3s2 3p4
sulfur
Which of the following will best help determine the direction of heat flow in a system? temperature enthalpy internal energy work pressure
temperature
Wavelength is..
the distance between successive peaks in a wave
In order for an endothermic reaction to be spontaneous,
the entropy increase in the system must be greater than the entropy decrease in the surroundings.
Frequency is...
the number of waves passing a fixed point in one second
Which of the following experiments provided evidence that the electrons in atoms are arranged in distinct energy levels?
the observation of line spectra from gas discharge tubes
The number that describes the main energy level of an electron in an atom is...
the principal quantum number, n
Consider an ideal gas enclosed in a 1.00 L container at an internal pressure of 20.0 atm. Calculate the work, w, if the gas expands against a constant external pressure of 1.00 atm to a final volume of 20.0 L. Now calculate the work done if this process is carried out in two steps. First, let the gas expand against a constant external pressure of 2.00 atm to a volume of 10.0 L. From the end point of step 1, let the gas expand to 20.0 L against a constant external pressure of 1.00 atm.
w = -1930 w = -2800 J
109.5
what is the bond angle around each central carbon?
94 g/mol
what is the molar mass?
Resonance is a concept that describes the bonding in molecules...
where there is more than one choice of location for a double or triple bond as deduced from Lewis dot structures. The true bonding is the average over all possible multiple bond locations.
CH2Cl2 IOF5 AsF3
which of the following are polar? CH2Cl2 IOF5 CF4 AsF3
Can an electron in an atom be in an energy level described by the set of quantum numbers n=5, ℓ=3, mℓ=-2?
yes
At constant temperature and pressure, the change in Gibbs free energy is defined as...
ΔG=ΔH−TΔS
The definition of internal energy is ΔU = q + w Which of these three values are state functions? Select all of the correct answers. ΔU w q
ΔU
A particular protein folds spontaneously at 25 ◦C and 1 atm. During this folding, the pro- tein changes conformation from a higher en- tropy unfolded state to a lower entropy folded state. For this process, ∆H is 1. No way to know 2. ∆H < 0 3. ∆H = 0 4. ∆H > 0
∆H < 0