Chemistry J117 Past Exam/Practice Exam Questions

-5,161

A 0.500 g sample of naphthalene (C10H8) is burned in a bomb calorimeter with an initial temperature of 20.0 °C. After the reaction, the final temperature is 26.4 °C. The heat capacity of the calorimeter is 3.15 kJ/°C. Calculate the energy of combustion of naphthalene in kJ/mol.

0.739

A 35.5 g sample of a metal is heated to 155 °C in an oven and added to 125.0 g of water at 25.0 °C. Once the metal and water reach equilibrium, the temperature is 31.2 °C. What is the specific heat capacity of the metal? The specific heat capacity of water is 4.184 J/ g·C.

35.08 degrees

A 52.1 g sample of a metal is heated to 172 °C in an oven and added to 125.0 g of water at 25.0 °C. Calculate the temperature once the metal and water reach equilibrium. The specific heat capacity of the metal is 0.739 J/(g °C). The specific heat capacity of water is 4.184 J/(g °C)

2

A bomb calorimeter was calibrated by burning a sample of benzoic acid (C6H5COOH), whose energy of combustion is -3227 kJ/mol. When 1.890 g of benzoic acid is burned in the calorimeter, the temperature of the calorimeter increases by 20.4 °C. Calculate the heat capacity of the calorimeter in kJ/°C.

The carbon-oxygen bond length is between 143 pm and 121 pm. (~132 pm)

A carbon-oxygen single bond has an average length of 143 pm and a carbon-oxygen double bond has an average length of 121 pm. What statement best describes the carbon-oxygen bond length in formamide?

delta H = +235 kJ delta E = +212 kJ

A reaction absorbs 235 kJ of heat and does 23 kJ of work. What is the value of ΔH and ΔE for the reaction?

0.235

Ammonia (NH3) is formed via the following reaction between hydrogen (H2) and nitrogen (N2): 3 H2 (g) + N2 (g) ⟺ 2 NH3 (g) For a particular experiment at equilibrium, it was found that the molar concentrations of the three species were as follows: [H2(g)] = 0.162 M, [N2(g)] = 0.100 M, and [NH3(g)] = 0.0100 M. What is the equilibrium constant (Kc) for this experiment?

915

Ammonia is commonly used as a fertilizer and is produced in the reaction: N2 (g) + 3 H2 (g) --> 2 NH3 (g) How many grams of ammonia are produced when 756 grams of nitrogen are reacted with 250.0 grams of hydrogen?

Electron not only have particlelike properties, but they also exhibit wavelike properties.

An beam of electrons is directed at a surface with two narrow slits. A screen that detects electron collisions is placed on the opposite side. What conclusions about the nature of electrons can be drawn from this result?

1s

An electron in which orbital experiences the highest effective nuclear charge?

no

Are the following structures resonance structures?

yes

Are the following structures resonance structures?

0.128

At 100∘ C, Kp = 60.6 for the reaction: 2 NOBr (g) ⇔ 2 NO (g) + Br2 (g) What is the value of Kp for the reaction below? NO (g) + 1/2 Br2 (g) ⟺ NOBr (g)

delta H

At constant pressure, what quantity is equal to the heat transfer (q)?

delta E

At constant volume, what quantity is equal to the heat transfer (q)?

Ethane<pentane<docosene

At room temperature docosene (C22H44) is a solid, ethane (C2H4) is a gas, and pentane (C5H12) is a liquid. a. Order the substances from weakest to strongest intermolecular forces.

dispersion forces

At room temperature docosene (C22H44) is a solid, ethane (C2H4) is a gas, and pentane (C5H12) is a liquid. b. What types of intermolecular forces are present in each substance?

Docosene is a very long molecule that also has a much higher molar mass. Therefore, it will have the strongest IMF also because it is a solid at room temperature. Long molecules tend to have stronger IMF due to the increase in dispersion forces. Ethane is a short molecule that is a gas at room temperature. It will have weaker IMF and not held tightly together.

At room temperature docosene (C22H44) is a solid, ethane (C2H4) is a gas, and pentane (C5H12) is a liquid. c. Explain how differences in intermolecular forces lead to the different phases of the substances ethane, pentane, and docosene.

1200

At what distance from the nucleus is the 90% boundary surface for a 3s orbital?

K2TiO4

Based on the electron configuration of titanium, which of the following compounds in unlikely to exist? K2TiO4 TiCl3 K3TiF6 TiCl4

7.41 x 10^14 Hz

Blu-Ray discs are read by a laser with a wavelength of 405 nm. Calculate the frequency of the radiation.

3,623

Calculate the amount of heat (in joules) needed to raise the temperature of 64.2 grams of water from 24.2 to 37.7 ∘C. The specific heat of water is 4.18 J/ g ∘C.

96

Calculate the amount of heat (in kilojoules) needed to raise the temperature of 325 mL of water from 22.1 to 92.4 °C. The specific heat of water is 4.18 J/(g °C).

-1

Calculate the formal charge on nitrogen in the electron-dot structure for OCN ̶

-2,857

Calculate the work (in Joules) associated with a chemical reaction with an initial volume of 1.1 L and a final volume of 8.0 L. The external pressure is 4.1 atm.

+48.6 kJ/mol

Calculate ΔH°f in kJ/mol for benzene (C6H6) from the following data: 2 C6H6(l) + 15 O2(g) ⟶ 12 CO2(g) + 6H2O(l) ΔH° = -6534 kJ ΔH°f (CO2) = -393.5 kJ/mol ΔH°f (H2O) = -285.8 kJ/mol

2, 39 C

Compare the following two ionic liquids. One figure represents tetraheptylammonium bromide and the other represents tetraheptylammonium iodide. One compound has a melting point of 88 ∘C and the other has a melting point of 39 ∘C. Tetraheptylammonium bromide is represented by figure _____. Tetreheptylammonium bromide has a melting point of _____.

Cl2 (g) + CHCl3 (g) --> HCl (g) + CCl4 (g)

Consider the three-step mechanism. a. Write the overall reaction

CCl3 (g) and Cl (g)

Consider the three-step mechanism. b. Identify any intermediates

rate = k[Cl2]^1/2[CHCl3]

Consider the three-step mechanism. c. Derive the rate law

2 bonds, 2 lone pairs of electrons

Draw the electron dot structure for ClF2+. How many bonds and how many lone pairs of electrons are around Cl?

2 bonds, 2 lone pairs of electrons

Draw the electron dot structure for H2Se. How many bonds and lone pairs of electrons are around Se?

high, vacant

Elements that have large negative electron affinities generally have _____ (high/low) values for Zeff and _____ (filled/vacant) valence orbitals.

503.25 kJ/mol

Estimate the strength of the carbon-carbon bond strength in benzene given the reaction and bond dissociation energies.

Each carbon in the ring contains the same number of sigma and pi bonds and also contains an even sharing of eectron density.

Experimental measurements show that all the carbon-carbon bonds in benzene are the same length and have an equal distribution of electron density in all the carbon-carbon bonds. Explain why this is observed.

1.07%

Fluorine-18 is a diagnostic radioactive isotope used to investigate the uptake of glucose within the body. The reaction is first order in fluorine-18 and has a rate constant of 6.3 x 10-3 min-1. What percent of the initial sample would remain in the patient's system after 12 h?

2, 0, 2

For OF2, the central atom has _____ single bonds, _____ double bonds, and _____ lone pairs of electrons.

4

For a first-order reaction, calculate the half-life (in years) of an isotope if it decays to 12.5% of its initial concentration in 12 years.

0.0303 h^-1

For a general first order reaction, A → products, 35.0% of A has reacted after 14.2 hours. What is the value of the rate constant in units of h-1?

2, 1, 0

For nitrate (NO3-), the central atom has _____ single bonds, _____ double bonds, and _____ lone pairs of electrons.

480 kJ

Gasoline (octane) burns according the following equation. 2 C8H18 (l) + 25 O2 (g) →16 CO2 (g) +18 H2O (l) ΔH°= ̶ 10,943 kJ How much heat is released when 10.0 g of octane is burned? (The molar mass of C = 12.0 g/mol, the molar mass of H = 1.0 g/mol).

T-shaped, 90 degrees, 180 degrees

Give the geometry and bond angles around chlorine in ClF3.

trigonal pyramidal, approximately 109.5 degrees

Give the geometry and bond angles around chlorine in ClO3-.

bent, approximately 120 degrees

Give the geometry and bond angles around selenium in SeO2.

2.1 x 10^-5

Given 2SO2(g)+O2(g)⇔2SO3(g) Kc=2.2×102 What is the value of Kc for the reaction below? 4SO3(g)⟺4SO2(g)+2O2(g)

-1,300

Given the following thermochemical equations, P4 (s) + 3 O2 (g) → P4O6 (s) ΔH° = ̶ 1640.1 kJ P4 (s) + 5 O2 (g) → P4O10 (s) ΔH° = ̶ 2940.1 kJ calculate ΔH° for the following reaction in kJ. P4O6 (s) + 2 O2 (g) → P4O10 (s)

156.1

Given the following thermochemical equations, calculate delta H for the final reaction in kJ. N2O(g) + NO2(g) ⟶ 3NO(g)

0.23 M/s

HI dissociates to for I2 and H2 according to the following reaction: 2HI(g) ⟶ H2(g) + I2(g) If the rate of loss of HI is 0.45 M/s, what is the rate of appearance of I2?

2

How many nodes does a 3s orbital have?

16

How many total orbitals are in the shell n = 4?

1.68 x 10^3 kJ

How much energy is required to decompose 765 g of PCl3, according to the reaction below? 4 PCl3(g) → P4(s) + 6 Cl2(g) ΔH° = +1207 kJ The molar mass of PCl3 is 137.32 g/mol.

Ga

Identify the atom with the following orbital filling diagram.

Ni2+

Identify the ion with the following orbital filling diagram. (Zn2+, Fe2+, Cu2+, Co+, or Ni2+)

17

If the rate of a reaction increases by a factor of 1.7 when the temperature is raised from 25 to 50 degrees Celsius, what is the value of the activation energy in kJ/mol?

35

If the rate of a reaction increases by a factor of 1.8 when the temperature is raised from 45 to 60 degrees Celsius, what is the activation energy in kJ/mol?

36 s

In aqueous solution, hypobromite ion, BrO−, reacts to produce bromate ion, BrO3−, and bromide ion, Br−, according to the following chemical equation. 3 BrO− (aq) → BrO3− (aq) + 2 Br−(aq) A plot of 1/[ BrO−] vs. time is linear and the slope is equal to 0.056 M-1 s-1. If the initial concentration of BrO− is 0.50 M, how long will it take one-half of the BrO− ion to react?

0.21454

In the reaction AB-->A+B, was monitored as a function of time. A plot of ln[AB] vs. time was found to have a slope equal to -0.059 min-1. If the initial concentration of AB is 0.500 M, what are the concentrations of A and B after 9.5 minutes?

23.2

Instant cold packs contain a solid and a pouch of water. When the pack is squeezed, the pouch breaks and the solid dissolves, decreasing the temperature of the solution. The following reaction is used to make a cold pack. NH4NO3(s)⟶NH4NO3(aq)ΔH=+26.0kJ What is the final temperature of the solution in ∘C when 16.5 grams of NH4NO3 is added to 92.2 grams of water at 35.0 ∘C ? The specific heat of the solution is 4.18 J/ g ∘C and the molar mass of NH4NO3 is 80.0 g/mol.

lower, the valence electron in K is in a higher energy orbital

K has a _____ ionization energy than Na because _________.

false, false, true, true

Label the following statements about equilibrium as true or false: 1. Adding a catalyst will increase the amount of products. 2. The concentrations of reactants and products are constant. 3. The rate of the forward reaction equals the rate of the reverse reaction. 4. The value of the equilibrium constant will change if the temperature changes.

dispersion, dipole-dipole

Name all the intermolecular forces in a sample of CH3F.

dispersion

Name all the types of intermolecular forces in a sample of C6H14.

hydrogen bonding, dispersion, dipole-dipole

Name all the types of intermolecular forces in a sample of CH3OH.

Bi<As<N Bi would have the lowest first ionization energy due to the fact that it has an abundance of more, larger orbitals as it is further down in the group, meaning that it would experience a lesser Zeff and therefore less of a positive nuclear pull, making it easier to ionize. N would have the highest first ionization energy as it experiences a greater Zeff, and it really wants to attract an electron in order to become very stable.

Order the following elements from lowest to highest first ionization energy and explain why: As, N, Bi

Br<Co<Ca; Of these elements, bromine has the smallest atomic radius because it is farthest to the right on the periodic table. This means that this element experiences the strongest effective nuclear charge (Zeff) because there is a stronger pull from a more positive nucleus than the other two elements. This then means that the positively charged nucleus will hold the negatively charged electrons much stronger as well. Calcium has the largest atomic radius as it is farthest to the left on the periodic table, given the fact that all three elements are in the same row on the periodic table. Because calcium is farthest to the left, it will experience a lesser effective nuclear charge as there are not as many positively charged protons in the nucleus pulling the negatively charged electrons as strong as you would see in bromine, for example. This means that the electrons are not held as tightly and therefore has a larger atomic radius.

Order the following elements from smallest to largest atomic radius and explain why: Br, Ca, Co

b < a < d < c

Order the following liquids from lowest to highest boiling point.

Sr2+ < Rb+ < Br- < Se2-

Order the following set of ions from smallest to largest ionic radius. Sr2+, Se2-, Rb+, Br-

CH2F2

Predict which substance has the highest boiling point. CH2F2 CF4 CH4 F2

H2O

Predict which substance has the highest boiling point. H2Se O2 H2O H2Te

negative, negative

Propane is a fuel used in camping stoves. The combustion reaction is: C3H8 (g) + 5 O2 (g) ⟶ 3 CO2(g) + 4 H2O (g) The sign of q for the reaction is _____, and the sign of work for the reaction is _____.

dipole-dipole, hydrogen bonding, dispersion

Select all the types of intermolecular forces in a sample of HF.

dipole-dipole, dispersion

Select all the types of intermolecular forces in a sample of PH3.

0.042 M

Sucrose, a sugar, decomposes in acidic solution to produce glucose and fructose. The reaction is first order in sucrose and at 25°C the rate constant is: k = 3.60×10−3h−1 . If the initial concentration of sucrose is 0.050 M, what is the concentration after 2 days?

gold

Suppose that 10.0 g of different metal objects, initially at 25°C, each absorb 175 J of heat. Which metal will have the highest final temperature? The specific heat capacity of each metal is given in units of J/(g∙°C). silver (c = 0.235) gold (c = 0.129) aluminum (c = 0.902) copper (c = 0.385) iron (c = 0.450)

128 kJ/mol

Suppose that the activation energy (Ea) for a forward reaction is 173 kJ/mol and ΔE for the forward reaction is 45 kJ/mol. Calculate Ea for the reverse reaction.

-55.8

Suppose you mix 200.0 mL of 0.200 M RbOH(aq) with 100.0 mL of 0.400 M HBr (aq) in a coffee cup calorimeter. The initial temperature of each of the two solutions was 24.40 °C and after mixing the temperature of the solution was 26.18 °C. Assume the specific heat capacity of the solution is the same as water, 4.18 J/(g ·°C). The density of the solution is 1.0 g/mL. What is ΔH° (in kJ per mole of RbOH) for the reaction shown below? RbOH (aq) + HBr (aq) → H2O (l) + RbBr (aq)

-50.2

Suppose you mix 50.0 mL of 0.600 M NaOH(aq) with 100.0 mL of 0.3 M HCl(aq) in a coffee cup calorimeter. The initial temperature of each of the two solutions was 24.9 °C and after mixing the temperature of the solution was 27.3 °C. Assume the specific heat capacity of the solution is the same as water, 4.184 J/(g °C). The density of the solution is 1.0 g/mL. What is ΔH° (in kJ/mole of NaOH) for the reaction shown below? NaOH(aq) + HCl(aq) ⟶ H2O(l) + NaCl(aq)

true

T/F: The carbon atoms and hydrogen atoms in benzene all lie in the same plane.

false

T/F: The carbon atoms and hydrogen atoms in cyclohexane all lie in the same plane.

weaker, low, large

The attractive forces between ions in an ionic liquid are _____ than the attractive forces between ions in an ionic solid. When choosing ions for an ionic liquid, you should select ions with _____ charges and _____ sizes.

Yes, it makes sense because it is close to the average of the two bond disassociation energies. This is observed due to the equal sharing of electrons in benzene and because each carbon contains the same amount of double and single bonds.

The average carbon-carbon single bond has a bond dissociation energy of 350 kJ/mol. The average carbon-carbon double bond has a bond dissociation energy of 728 kJ/mol. Does your calculated answer make sense based on these measured bond strengths? Explain.

89

The fertilizer, ammonia, is produced in the following reaction: N2 (g) + 3 H2 (g) --> 2 NH3 (g) How many grams of ammonia (NH3) are produced when 500.0 grams of nitrogen (N2) are reacted with 15.7 g of hydrogen (H2)?

Al

The figure represents successive ionization energies for a third period element. Identify the element.

polar

The following image shows an electrostatic potential map for lithium hydride (LiH). a. The lithium hydride molecule is _____ (polar/nonpolar)

partially negative, red

The following image shows an electrostatic potential map for lithium hydride (LiH). b. The side of the molecule with hydrogen is _____ _____ (partially negative/positive) and is shown in the color _____.

partially positive, blue

The following image shows an electrostatic potential map for lithium hydride (LiH). b. The side of the molecule with lithium is _____ _____ (partially negative/positive) and is shown in the color _____.

Attractive forces affect the energy. When two atoms are far apart, they will have little to no interaction energy, as there is too much distance between them to have a significant force of attraction. When the atoms get closer, the interaction energy decreases, which indicates a favorable interaction and the forming of a bond. But, if they get too close, then they will start to repel from one another and becomes unfavorable.

The following image shows the potential energy as two atoms approach to make a bond. a. Explain the shape of the curve. What forces affect the energy?

around 3.7

The following image shows the potential energy as two atoms approach to make a bond. b. At what internuclear distance is the bond length?

termolecular, first, rate = k[H2][NO]^2

The following two-step mechanism has been proposed for the reduction of NO by hydrogen. Step 1: H2(g) + 2 NO(g) ⟶ N2O(g) + H2O(g) (slow) Step 2: N2O(g) + H2(g) ⟶ N2(g) + H2O(g) (fast) 1. The molecularity of rate law for the first step of the mechanism is _____. 2. The order of N2O in the rate law for the second step of the mechanism is _____ order. 3. The rate law for the overall reaction is: ___________________.

2.5 x 10^-5 M/s

The graph shows the data for the reaction 2NO2 (g) --> 2 NO (g) + O2 (g) Use the graph to calculate the average rate of loss of NO2 in the time period 0-100 seconds.

n=3; there are 2 nodes (3s orbital)

The graphs represent an s orbital in the hydrogen atom. The graphs plot the wavefunction, ψ (top), the square of the wavefunction, ψ2 (middle), and the square of the wavefunction times 4 π r2 (bottom) which is the radial distribution function for the same orbital. a. What is the principal quantum number, n, for this orbital? Explain how you were able to determine the value of n from these plots.

~700 pm

The graphs represent an s orbital in the hydrogen atom. The graphs plot the wavefunction, ψ (top), the square of the wavefunction, ψ2 (middle), and the square of the wavefunction times 4 π r2 (bottom) which is the radial distribution function for the same orbital. b. At what distance from the nucleus are you most likely to find the electron in this orbital?

~1200 pm

The graphs represent an s orbital in the hydrogen atom. The graphs plot the wavefunction, ψ (top), the square of the wavefunction, ψ2 (middle), and the square of the wavefunction times 4 π r2 (bottom) which is the radial distribution function for the same orbital. c. If we were to represent this s orbital in the usual way by drawing a sphere to represent a 90% probability surface, at what radius would we want to draw the sphere?

0.070 M

The half-life for the first order decomposition of H2O2 is 10.7 hours. If the initial concentration of H2O2 is 0.56 M, what is the concentration after 3 half-lives?

421 kJ/mol

The ionization energy of an atom can be measured by photoelectronic spectroscopy, in which light is directed at an atom, causing an electron to be ejected. What is the ionization energy of an element in (kJ/mol) if light with a wavelength of 142 nm produces electrons with a velocity of 1.240 x 106 m/s? The mass of an electron is 9.11 x 10-31 kg.

Ea = 60 kJ/mol and ΔE = -20 kJ/mol

The potential energy profile for the one step reaction AB + CD → AC + BD is shown. The energies are given in units of kJ/mol. What are the values of Ea and ΔE for the REVERSE reaction?

50

The rate constant (k) for the first-order decay of tritium (3H) is 0.056 y-1. Tritium concentration can be used as a dating technique for wine samples. When a wine sample was analyzed for its 3H content, it was found to contain 6.08% of the 3H originally present when the wine was produced. How old is the wine (in years)?

new rate = 4.5 x original rate

The reaction 2NO(g) + 2H2(g) ⟶ N2(g) + 2H2O(g) has the following rate law: rate=k[H2][NO]2. By what factor does the rate change if the concentration of hydrogen is halved and the concentration of nitric oxide is tripled?

first, second, third

The reaction O2(g)+ 2 NO (g) ⟶ 2 NO2(g) has the rate law: Rate = k[O2][NO ]^2. The reaction is _____ order in O2 and _____ order in NO. The overall order of the reaction is _____.

The rate constant is found by plotting [A] vs. time. The slope = -k.

The reaction A --> B is zeroth order. Which of the following statements is correct? a. The rate constant is found by plotting [A] vs. time. The slope = -k. b. The rate constant is found by plotting 1/[A] vs. time. The slope = k. c. The rate constant is found by plotting ln [A] vs time. The slope = -k

The difference between diagram I and diagram II is likely due to a difference in the temperature of the reaction.

The reaction A → B is represented by the energy diagrams I and II. Which statement is FALSE? a. Diagram II represents a mechanism with a fast first step and a slow second step. b. In diagram I, the activation energy for the reverse reaction is greater than the activation energy for the forward reaction. c. The difference between diagram I and diagram II is likely due to the addition of a catalyst. d. The difference between diagram I and diagram II is likely due to a difference in the temperature of the reaction. e. The reaction A→B is exothermic.

reaction mixture 4

The reaction A2 + B2 ⇌ 2 AB has an equilibrium constant Kc = 9. The following pictures represent reaction mixtures that contain A2 molecules (shaded) and B2 molecules (unshaded), and AB molecules. Which reaction mixture is at equilibrium?

rate = k[A][B]

The relative rates of the reaction A+ B → products in vessels (1)-(4) are 1 : 2 : 2 : 4. Red spheres represent A molecules and blue spheres represent B molecules. What is the rate law of the reaction?

no electrons emitted, no current measured

The wavelength required to cause the photoelectric effect in potassium is 541 nm. a) What is observed when bright light with a wavelength of 580 nm is shown on the potassium?

no electrons emitted, no current measured

The wavelength required to cause the photoelectric effect in potassium is 541 nm. b) What is observed when dim light with a wavelength of 580 nm is shown on the potassium?

electrons emitted, relatively high current measured

The wavelength required to cause the photoelectric effect in potassium is 541 nm. c) What is observed when bright light with a wavelength of 535 nm is shown on the potassium?

electrons emitted, relatively low current measured

The wavelength required to cause the photoelectric effect in potassium is 541 nm. d) What is observed when dim light with a wavelength of 535 nm is shown on the potassium?

81,723

To produce a high-quality image with an electron microscope the wavelength of an electron must be about 10 times less than the diameter of the particle to be imaged. What electron velocity (in m/s) is required if a 89 nm particle is to be imaged? The mass of an electron is 9.11 x 10-31 kg.

-109 kJ

Use data for bond dissociation energies to estimate ΔH° for the following reaction in kJ. CH4(g) + Cl2 (g) → CH3Cl (g) + HCl (g)

structure 1

Use formal charge to determine which of the following resonance structures makes the largest contribution to the resonance hybrid.

-2855 kJ/mol

Use the following standard enthalpy of formation data to calculate ΔH° for the combustion reaction of butane, [C4H10 (l)].

11,517.7

Use the following thermochemical equation to calculate the amount of heat (in kJ) evolved when 80.6 grams of hydrogen gas reacts with excess oxygen to form liquid water. 2H2(g)+O2(g)⟶2H2O(l) ΔH=−571.6kJ

5.2

Use the graph to determine the value of the equilibrium constant (Kc) for the reaction, A2 (g) ⇌ 2A (g).

Mg(s) + C(s) + 3/2 O2(g) ⟶ MgCO3(s)

What equation represents the standard enthalpy of formation reaction for MgCO3?

positive and negative phases

What is represented by the pink and blue lobes of the orbital?

CaO

What is the chemical formula for the compound that forms between the elements calcium and oxygen?

a quantized region of space where an electron is likely to be found

What is the definition of an orbital?

sp

What is the hybridization of the central atom in the SCN- ion?

sp2

What is the hybridization of the central atom in the SO2 molecule?

trigonal planar, 120 degrees

What is the molecular shape/bond angles of COCl2?

tetrahedral, 109 degrees

What is the molecular shape/bond angles of SiBr4?

404

What is the wavelength (in nm) of light with an energy of 296 kJ/mol?

97.2 nm

What is the wavelength of the photon emitted when an electron drops from a 4f orbital to a 1s orbital in a hydrogen atom? (nm)

a. sigma C(sp2)-O(sp2) and pi C(2px)-O(2px) b. C(sp3)-O(sp3)

What orbitals overlap to form a) bond 1 b) bond 2 in the following molecule.

-3,540

When 0.187 g of benzene, C6H6, is burned in a bomb calorimeter, the temperature rises by 3.45 C. If the heat capacity of the calorimeter is 2.46 kJ/C, calculate the combustion energy (ΔE) in units of kJ/mol of benzene.

-22.8

When 13.0 g of KCl dissolves in 400.0 mL of water in a coffee cup calorimeter, the temperature of the water changes from 22.6 °C to 24.9 °C. Assume the specific heat capacity of the solution is the same as water, 4.18 J/(g ·°C). What is ΔH° for the reaction shown below in kJ/mol of KCl? KCl(s) → K+(aq) + Cl ̶ (aq) (The molar mass of KCl is 74.55 g/mol)

-42.9

When 13.0 g of NaOH dissolves in 400.0 mL of water in a coffee cup calorimeter, the temperature of the water changes from 22.6°C to 30.7°C. Assume the specific heat capacity of the solution is the same as water, 4.18 J/(g ·°C). What is ΔH° for the reaction shown below in kJ/mol of NaOH? NaOH (s) → Na+ (aq) + OH ̶ (aq)

negative, positive

When hot steam condenses on a cold mirror, the sign of q is _____ and the sign of w is _____.

This occurs because the energy levels are quantized. Electrons can only jump to defined levels, and cannot be between levels.

When sodium chloride is burned in a flame, a brilliant yellow color results. The yellow color results when an electron falls from a 3p to a 3s orbital. a. Explain why the emission spectrum for sodium only contains sharp "lines".

n=3, l=1, ml= -1, 0, +1, ms=+/- 1/2

When sodium chloride is burned in a flame, a brilliant yellow color results. The yellow color results when an electron falls from a 3p to a 3s orbital. b. Write a set of quantum numbers for the electron when it is in the 3p orbital (the excited state).

n=3, l=0, ml=0, ms=+/- 1/2

When sodium chloride is burned in a flame, a brilliant yellow color results. The yellow color results when an electron falls from a 3p to a 3s orbital. c. Write a set of quantum number for the electron when it is the 3s orbital (the ground state).

3.37 x 10^-19 J/photon

When sodium chloride is burned in a flame, a brilliant yellow color results. The yellow color results when an electron falls from a 3p to a 3s orbital. d. Sodium emits light with a wavelength of 589.0 nm. Calculate the energy change when one electron falls from a 3p to a 3s orbital.

203 kJ/mol

When sodium chloride is burned in a flame, a brilliant yellow color results. The yellow color results when an electron falls from a 3p to a 3s orbital. e. Calculate the energy change when one mole of electrons falls from a 3p to a 3s orbital. (kJ/mol)

This would require a high amount of energy, therefore a very small wavelength. This spectrum only portrays 400 nm as its smallest wavelength, which the energy required to excite an electron to this degree would require a much shorter wavelength.

When sodium chloride is burnterm-33ed in a flame, a brilliant yellow color results. The yellow color results when an electron falls from a 3p to a 3s orbital. f. An electron can also be excited from a 3s to a 4p orbital, but we do not observe this emission line in the above spectrum. Explain.

A

Which arrow in the energy diagram for an atom represents the absorption of light with the shortest wavelength?

As

Which element has the following quantum numbers for its valence electrons?

figure d

Which figure shows the correct electron-dot structure for a molecule with the following connections of atoms?

B

Which is the correct orbital filling diagram for Mn4+?

4, 2 (d orbital)

Which n and l quantum numbers correspond to the fourth shell orbital shown below?

CaS

Which of the following compounds has the highest lattice energy? KCl CaS Rb2S Cs2Br

KI

Which of the following ionic compounds will have the LOWEST lattice energy? KBr, KF, KI, or K2O

structure 3

Which of the following resonance structures makes the largest contribution to the resonance hybrid?

3s

Which orbital has the highest energy?

iridium (1.298)

You have a series of metal blocks, weighing 20 g each, that are initially at 72 °C. The blocks each absorb 125 J of heat. Which metal block will have the lowest final temperature? iridium (1.298) potassium (0.7536) lead (0.125) cadmium (0.2303) scandium (0.5862)