Quimica Inorganica Spellbook

Question 1

What type of bond is found in carbon monoxide?

A) Nonpolar single bond

B) Polar single bond

C) Polar double bond

D) Polar triple bond

Answer 1

(D) The Lewis Dot Structure for carbon monoxide has a triple bond that is polar, with the oxygen being slightly negative due to its higher electronegativity.

Question 2

The Ksp value for silver iodide, AgI, is 4 x 10^-16. What is the molar solubilitry of silver iodide?

A) 2 x 10^-8

B) 2 x 10^-16

C) 8 x 10^-16

D) 8 x 10^-32

Answer 2

(A) Because the concentrations of silver and iodide ions are equal, the expression to be solved is 4 x 10^-16 = x² where x = 2 x 10^-8

Question 3

If a sample of gas is heated from 10°C to 20°C, the volume of the gas will:

A) increase slightly from the original volume

B) be double the original volume

C) decrease slightly from the original volume

D) be half of the original volume

Answer 3

(A) In order to qualitatively determine the effects of temperature on a gas, the temperature must be in Kelvin, so the change in temperature is from 283 K to 293 K, or about 3%.

Question 4

Which of these elements have the highest electronegativity?

A) Sodium

B) Silicon

C) Sulfur

D) Selenium

Answer 4

(C) High electronegativities are features of nonmetallic elements, with the highest electronegativity value assigned to fluorine.

Question 5

What type of reaction is taking place in the precipitate formations?

A) Hydrolysis reaction

B) Single replacement reaction

C) Synthesis reaction

D) Double replacement reaction

Answer 5

(D) Each precipitate reaction is a double replacement (or double displacement) reaction.

Question 6

The solubility product constant for silver chloride is 4 x 10^-10. What is the solubility of silver chloride in a solution of 0.1 M NaCl?

A) 2 x 10^-5

B) 4 x 10^-5

C) 4 x 10^-9

D) 4 x 10^-11

Answer 6

(C) This is an applicaiton of the common ion effect. Because the concentration of the Cl- ion is 0.1 M, the addition of a very small amount of the Cl- ion from AgCl is small enough to be ignored, so 4 x 10^-10 = 0.1x where x is going to be equal to 4 x 10^-9 M.

Question 7

Ice at zero degrees Celsius is palced in water at zero degrees Celsius. Which of the following would occur?

A) The ice melts

B) All of the ice melts but part of the water also freezes

C) None of the ice melts and none of the water freezes

D) Some of the ice melts and some of the water freezes

Answer 7

(C) If the temperature is the same, no heat flow.

Question 8

Pure bromine has a density of 3.2 g/cm³ at room temperature. What is the molarity of pure bromine?

Answer 8

20.0 M. At room temperature, there are (3.2 g/cm³ x 1000 cm³/L) 3200 g of bromine and so dividing it by 160 (Br₂ = 80 + 80 = 160) would make a molarity of 20.0 M.

Question 9

When 20.0 mL of a 0.1 M solution of potassium hypochlorite is added to 10.0 mL of a solution of 0.1 M solution of hypochlorous acid with a few drops of phenol red added to it, what color change, if any, would be observed?

(Hint: Phenol Red is yellow in acidic conditions and red in basic conditions)

Answer 9

Adding the basic salt KClO to a weak acid would increase the pH enough for it to become basic. So it would turn from yellow to red.

Question 10

The equation below is unbalanced:

ClO₃^-1 + Mn⁺² -> Cl₂ + MnO₄^-1

What happens to the chlorine atoms in the process of the equation?

Answer 10

Chlorine atoms are reduced and each chlorine atom gains 5 electrons.

Oxidation Number of chlorine in the reactants: x - 6 = -1

x = 5

Oxidation Number of chlroine in the products: x = 0

x = 0

Question 11

Consider the following excerpt from a reaction:

H₂SO₄(aq) -> 2CO₂

What volume of 4.0 M sulfuric acid is needed to produce 44.8 L of carbon dioxide gas at STP?

Answer 11

250 mL. To have a 4.0 M concentration, sulfuric acid needs to have 1 mole / 0.25 L. Seeing as one mole would create 2 moles of carbon dioxide (which is 44.8 L at STP), we need 250 mL of sulfuric acid.

Question 12

The heat of combustion of tristerain (molar mass = 926) is 37,000 kj/mole. By how many degrees Celsius could 1000 grams of water be heated using the heat produced by the combustion of one gram of tristearin? The specific heat capacity of water is 4.181 J/g ºC

Answer 12

The temperature change of water could be found using ΔH = mCΔT. 37,000 J = (926 g)(4.184 J/gºC)(ΔT)

ΔT = 9.5 degrees.

Question 13

The compound arsenic trichloride obeys the octet rule. What is the molecular geometry and polarity of phosphorous trichloride?

Answer 13

It is trigonal pyramidal in shape and it is polar.

Question 14

Which of the following pairs of 0.1 M solutions will produce a precipitate?

A) Silver nitrate and lead(II) chloride

B) Lead(II) nitrate and nitric acid

C) sodium bromide and calcium chloride

D) potassium nitrate and mercury(II) acetate

Answer 14

Silver chloride is an insoluble solid. So: (A)

Question 15

Given the equilibrium constants for the synthesis of hydrogen iodide (10^-1) and hydrogen chloride (10¹⁶), the rate of synthesis of HCl compared to the rate of formation of HI at the same temperature is:

Answer 15

Reaction rates cannot be determined from equilibrium constants or other thermodynamic data.

Question 16

Compared to aqueous HCl, the acidity of aqueous HI is:

Answer 16

HI is a stronger acid because I- ions are larger than Cl- ions, making HI bonds weaker than HCl bonds so HI more readily dissociates.

Question 17

When the boiling points of the silver nitrate [AgNO₃] and lead nitrate [Pb(NO₃)₂] solutions are compared, what results are obtained if both solutions are 0.1 M?

Answer 17

Boiling point elevation depends on the number of moles dissolved particles. Because the comparison is between equimolar solutions of lead nitrate and silver nitrate and because lead nitrate dissociates into three ions while silver nitrate dissociates into two ions, lead nitrate will have a higher boiling point.

Question 18

When a piece of magnesium metal is placed in a solution of copper(II) nitrate, what occurs?

Answer 18

Because magnesium is more reactive than copper, the magneisum metal will be oxidized to magnesium ion and the copper ion is reduced to copper metal.

Question 19

When lead (II) reacts with sulfuric acid, what is the most likely aqueous product?

Answer 19

PbSO₄ because SO₄ has a -2 charge and Pb has a +2 charge.

Question 20

What prediction can be made about the miscibility of hexane and toluene?

Answer 20

Hexane and toluene will be miscible in each other because they can have London dispersion forces to facilitate mixing. Both are nonpolar, which rules out hydrogen bonding and dipole interactions.

Question 21

Sulfur atoms can sometimes form compouns with more than four pairs of bonding electrons. Which orbitals are responsible for allowing sulfur atoms to do this?

A) 2p

B) 2d

C) 3d

D) 3p

Answer 21

(C) Expanded octets involve d orbitals. The second energy level has no d orbitals, so it cannot be correct.

Question 22

How do the rates of diffusion of Ar (molar mass = 40) and Br₂ (molar mass = 160) compare assuming both gases are at the same temperature and pressure?

Answer 22

Use Graham’s law, the rate of diffusion of gases are inversely proportional to the square root of their molar masses: v1/v2 = sqrt(m2/m1) so: v1/v2 = sqrt(160/40): Ar will diffuse twice as fast as Bromine.

Question 23

Water can be a Bronsted Lowry base because it can:

Answer 23

Accept a proton.

Question 24

Zn + HCl → ZnCl₂ + H₂
Consider the above unbalanced reaction. How many mL of a 4 M solution of HCl would be required to produce 22.4 L of H₂ gas at STP?

Answer 24

Since the reaction is unbalanced, we should balance it first, so we see

Zn + 2HCl → ZnCl₂ + H₂
which means that we need 2 moles of HCl for each mole of H₂ we want to produce. 22.4 L of gas at STP is 1 mole, so we need 2 moles of HCl to react. In a 4 M solution, 2 moles would be found in 1/2 L or 500 mL since the solution has 4 moles per liter and therefore 2 moles per half-liter.

Question 25

How many moles of Na+ ions were are there in the initial Na₂SO₄ solution used in this reaction:

Initially, 15.0 mL of 0.300 M Pb(NO₃)₂ was mixed with 15.0 mL of 0.300 M Na₂SO₄. All the Pb(NO₃)_a reacted to form Compound A, a white precipitate. Compound A was removed by filtration.

Answer 25

0. 009 moles. The initial solution in this reaction is 15 mL of 0.300 M Na₂SO₄:
   (15. 0 mL)(1 L)(0.300 mol Na₂SO₄)(2 mol Na^2+‑) / (1000 mL) (1 L Na₂SO₄)(1 mol Na₂SO₄) = 0.009 moles.

Question 26

Pb(OH)₂(s) is slightly soluble in water. How would the amount of Pb(OH)₂(s) that normally dissolves in 1 L of water be affected if the pH were 9.0?

A) Less would dissolve

B) The same amount would dissolve

C) More would dissolve

D) There is no way to predict the effect of the change in pH of the water

Answer 26

(A). Less would dissolve. At pH 9, the concentration of OH- is greater than the concentration of OH- at pH 7.Pb(OH)_s à Pb²⁺ + 2 OH- and so according to Le Chatelier’s Principle, with more products available, the reaction would shift toward the reactants

Question 27

Answer 27

Question 28

Answer 28

Question 29

Answer 29

Question 30

The ability of NH₃ to form coordination compounds with transition metal ions can best be accounted for by the fact that NH₃:

A) acts as an electron pair donor

B) is capable of hydrogen bonding

C) is a weak base in aqueous solution

D) contains N with a -3 oxidation number

Answer 30

(A) In a coordination compound between ammonia and a transition metal ion, a covalent bond is formed between the nitrogen atom of ammonia and the metal ion. The formation of such a bond is often called a Lewis acid-base reaction. The metal ion is deficient in electrons, and ammonia has a pair of electrons available for bonding. Therefore, both electrons that compromise the new covalent bond come from ammonia.

Question 31

An aqueous solution of a salt made by mixing which of the following acids and bases displays the lowest pH?

A) strong acid, weak base

B) strong acid, strong base

C) weak acid, weak base

D) weak acid, strong base

Answer 31

(A) Consider each of the interactions:

Strong acid, weak base

pH < 7

Strong acid, strong base

pH = 7

Weak acid, weak base

pH = 7

Weak acid, strong base

pH > 7

Question 32

At the stoichiometric (equivalence) point in a titration of benzoic acid with NaOH, the pH is:

A) < 4

B) > 4 and < 7

C) = 7

D) > 7

Answer 32

(D) The pH at the equivalence point in any titration is the pH of the salt solution formed. At the equivalence point, the solution contains sodium benzoate and water. Benzoic acid is a weak acid, so it must have a pH greater than 7

Question 33

If a student did NOT remove all the moisture from the KHP before the titration with NaOH to standardize the NaOH solution, then the molarity determined for the NaOH would be:

a) too high because the actual number of moles of KHP titrated would be less than the number used in the calculations
b) too low because the actual number of moles of KHP titrated would be more than the number used in the calculations
c) too low because the actual number of moles of KHP titrated would be less than the number used in the calculations
d) unaffected because the weighed KHP was dissolved in water, making any moisture in the sample unimportant

Answer 33

(A) If a student weighs a sample of KHP that contains moisture, the measurement will include the mass of KHP and water and will be larger than the mass of KHP alone. This will make the number of moles of KHP too high and since the number of moles of NaOH equals the number of moles of KHP at the equivalence point, the number of moles of NaOH will also be too high.

Question 34

Crystals precipitate when each of the following compounds is added to a saturated of KNO₃(aq) EXCEPT:

A) NH₄NO₃

B) Ca(NO₃)₂

C) NH₄Cl

D) KCl

Answer 34

(C) A saturated solution of KNO₃ contains the maximum number of K+ and NO₃ ions the solution can hold without precipitating solid KNO₃. The addition of any salt that adds either of these two ions will cause KNO₃(s) to form.

Question 35

Suppose that CH₄ reacts completely with O₂ to form CO₂ and H₂O with a total pressure of 1.2 torr. What is the partial pressure of H₂O?

A) 0.4 torr

B) 0.6 torr

C) 0.8 torr

D) 1.2 torr

Answer 35

(C)The balanced equation for the complete combustion of CH₄ is:

CH₄ + 2O₂ –> CO₂ + 2H₂O

The pressure of the gaseous products is 1.2 torr. For every three product molecules, two are water. Therefore, the partial pressure of water is 2/3 of the total pressure. 2/3 of 1.2 is 0.8 torr.

Question 36

Electrons in which of the following orbitals of Ti can form bonds with a substance X?

A) 2s

B) 3d

C) 4p

D) 5f

Answer 36

(B) Titanium, as a transition element, would be expected to interact via its valence shell 3d electrons. The ground state of Ti has the electron configuration [Ar] 3d² 4s². In the ground state, there are no 4p or 5f electrons. While Ti does have 2s electrons, they are in the core, much lower in energy than the valence electrons. They would not be expected to interact with neighboring atoms.

Question 37

Attached is a phase diagram for water. As the pressure applied to a sample of water at -0.1 degrees Celsius is increased from 1.0 torr to 200 atm at constant pressure, the:

A) vapor will become a solid then a liquid

B) vapor will become a liquid and then a solid

C) vapor will become and remain a solid

D) solid will become a liquid

Answer 37

(A) The sample will start off as a vapor since it is between the dotted lines at the 1 torr mark. 200 atm is about 152k torr, so at constant temperature, the vapor will turn into solid (deposition) and then it will eventually reach liquid.

Question 38

When a strip of Cu is placed into H₂O, no change is observed. However, when a strip of Cu is placed into a solution of HNO₃, a gas evolves. What is the most likely identity of the gas?

A) NO

B) CO₂

C) H₂

D) O₃

Answer 38

(A) Nitrogen monoxide is one gas evolved when copper metal is placed in a nitric acid solution. This is a red-ox reaction. Copper is oxidized and nitrogen is reduced. Nitric acid is an oxidizing agent. While the formation of H₂ is plausible, it is not observed because the much more electronegative nitrogen undergoes reduction more readily than does hydrogen.

Question 39

The pK_a for the dissociation of H₂PO₄^- to HPO₄^2- is 6.7. What is the initial ratio of [HPO₄^2-]:[H₂PO₄^-] in a buffer solution with pH equal to 8.7?

A) 1:1

B) 2:1

C) 100:1

D) 200:1

Answer 39

(C) Use the Henderson Hasselbach equation: pH = pK_a + log([base]/[acid] which is the same as:

8.7 = 6.7+ log(HPO₄²/ H₂PO₄^-). 2 = log(HPO₄²/ H₂PO₄^-). Thus, the ratio between the two entities is 10² or 100:1.

Question 40

n CDP ⇄ (CP)_n + n HPO₄^2- with PNP and Mg²⁺ as catalysts

According to this equation, the concentration of the polymer (CP) with respect to [HPO₄^2-] is:

A) n[HPO₄^2-]

B) n²[HPO₄^2-]

C) (1/n) [HPO₄^2-]

D) (1/n²) [HPO₄^2-]

Answer 40

(C) According to the balanced coefficients in Equation 1, each time one molecule of the polymer is formed, there are n hydrogen phosphate ions produced. Thus, the concentration of the polymer must be 1/n times the concentration of HPO₄^2-

Question 41

From reactions 3-5, what can be determined about the relative concentrations of CFC’s (F₃CCl) and O₂?

A) One equivalent of CFC is required to produce one equivalent of O₂

B) One equivalent of CFC is required to produce two equivalents of O₂

C) A catalytic amount of CFC can produce much O₂

D) The CFC is produced by a catalytic amount of O₂

Answer 41

(C) After the initial step of breaking the bond in the chlorofluorocarbon, the radicals are recycled. In other words, these two species act as catalysts: they react with the substrate (O₃ and O) and are re-formed. The re-formed radical can participate in another cycle of the reactions 4 and 5, thus a small amount of CFC can produce much O₂ by catalyzing the decomposition of ozone.

Question 42

Which of the following electron configurations depicts an atom in an excited state?

A) 1s²2s²2p⁶3s²3p⁶4s¹
B) 1s²2s²2p⁶3s²3p⁶4s²3d¹
C) 1s²2s²2p⁶3s²3p⁶4s¹3d¹
D) 1s²2s²2p⁶3s²3p⁵

Answer 42

(C) An atom in an excited state should have filled its orbitals in order and have one electron in a higher state than it should be. For (A), the orbitals have filled normally, as well as in (B) and (D). In (C), we see that the 4s only has 1 electron in it while the 3d has 1 electron in it. Normally, the 4s would have 2 electrons before the 3d gained one.

Question 43

Which of the following aqueous solutions would not produce a pH buffer solution?

I. A strong acid and a strong base
II. A strong acid and a weak acid
III. A strong acid and its conjugate base

A) III only
B) I and II only
C) II and III only
D) I, II, and III

Answer 43

(D) Buffer solutions are created with weak acids and their conjugate bases or with weak bases and their conjugate acids. Strong acids and strong bases will produce a salt and water (usually) which will not act as pH buffers. Strong acids and weak acids will simply produce an acidic solution which will still not act as buffers. Strong acids and their conjugate bases will not work either since a weak acid is needed. Therefore, none will produce a buffer solution and the answer is (D).

Question 44

Which of the following has the most positive oxidation state of carbon?

A) C₂H₆
B) CHCl₃
C) CH₄
D) C₂H₂

Answer 44

(B) The oxidation states of carbon are, respectively: -3, +2, -4, and -1. Thus (B) is the correct answer.

Question 45

Which of the following has the greatest first ionization energy?

A) Na
B) Mg
C) K
D) Ca

Answer 45

(B) The ionization energy (IE) is the energy required to remove an electron from an atom. On the periodic table, IE generally increases going from bottom to top and from left to right. Thus Mg and Ca both have higher ionization energies than Na and K, and Mg has a higher ionization energy than Ca.

Question 46

A particular liquid is brought up to boiling point. Some solute (for instance sodium chloride) is added to the solution. Which of the following would hold true?

A) The solution will stop boiling
B) The solution will boil more vigorously
C) Vapor pressure of the solution will decrease
D) Temperature will fall

Answer 46

(C) When solute is added to the liquid, it gets in the way of molecules at the surface, which are trying to escape out into the atmosphere. This results in a decreased capacity for the molecules of liquid to escape, thus vapor pressure of the solution will decrease. (A) is incorrect because we cannot be sure that the entire solution will desist boiling. This could definitely happen if a case of salt was added to a pot of boiling water, but it might not be the case for different amounts. (B) is incorrect, and we would not expect temperature to fall thus (D) is incorrect as well. Thus, (C) is the correct answer.

Question 47

What is the Lewis structure for hydrazine?

Answer 47

A nitrogen atom has 3 single electrons and 1 lone pair. Hydrogen has one electron. So nitrogen has three bonds and one lone pair.

Question 48

When electrons oscillate through the equilibrium point (B) and move to a maximum point (C), it is because of:

A) the momentum gathered as they moved from the other extreme, point A

B) Coulomb forces pulling on the electron sea

C) magnetic forces of attraction between the positive ions and the electron sea

D) the large potential energy at point B

Answer 48

[A] as electrons move from A to B, they convert potential energy to kinetic energy and gain velocity and hence momentum. This momentum is enough to allow the electrons to go from B to C.

Question 49

SiCl₃H has a normal boiling point of 33ºC. What are the predominant forces between SiCl₃H molecules?

A) ionic bonds

B) covalent bonds

C) hydrogen bonds

D) van der Waals forces

Answer 49

[D] Van der Waals forces are weak intermolecular attractive forces. They have relatively low boiling points because the forces are not strong.

Question 50

A gas that occupies 10 L at 1 atm and 25ºC will occupy what volume at 500 atm and 25ºC?

A) exactly 0.020 L

B) somewhat more than 0.02 L because the space occupied by the individual gas molecules

C) somewhat more than 0.02 L because of the repulsions between the individual gas molecules

D) somewhat more than 0.02 L because of the increased number of collisions with the sides of the container

Answer 50

[B] the ideal law makes the assumption that molecules have no volume. The assumption is adequate when the gas is at 1 atm, but when the pressure is increased to 500 atm the volume of the gas molecules is no longer negligible.

Question 51

The rate of NO₂ + OCl is slower than NO₂ + HOCl in forming NO₃ because the formation of HOCl by the protonation of oxygen:

a) reduces the electronic repulsion forces between the reactants
b) increases the electronic repulsion forces between the reactants
c) increases the electronic repulsion forces between the nitrogen atom and oxygen atom being transferred
d) reduces the electronic attraction forces between the chlorine atom and the oxygen atom that is being transferred

Answer 51

[A] two anions will experience electrostatic repulsion due to their negative charge. Protonation of the oxygen would generate an electrically neutral species and the repulsion forces would be reduced

Question 52

The energy, E, of a hydrogen atom with its electron in the nth shell of a hydrogen atom is given by E = -C/n² where n = 1,2,3…and C is a positive constant. If an electron goes from the n = 2 shell to the n = 3 shell.

A) a photon is emitted

B) an electron is emitted

C)an electron is absorbed

D) the energy of the atom is increased

Answer 52

[D] The energy of an electron in orbit n = 3 is less negative or greater than the energy in orbit n = 2. Thus energy is required to make the transition from n = 2 to n = 3 and the atom gains energy.

Question 53

Ba²⁺(aq) is an ion that is very toxic to mammals when taken internally. Which of the following compounds, mixed in water, would be the safest if accidentally swallowed?

A) BaSO₄, K_sp = 1.1 x 10^-10

B) BaCO₃, K_sp = 8.1 x 10^-9

C) BaSO₃, K_sp = 8.0 x 10^-7

D) BaF₂, K_sp = 1.7 x 10^-6

Answer 53

[A] The lower the K_sp, the lower the concentrations of cation and anion in aqueous solution and the lower the solubility of the compound in water. If mixed with water and accidentally swallowed, the Ba salt with the lowest value of K_sp would be the safest

Question 54

When aqueous solutions of the various anions and cations were mixed, precipitates formed because:

A) few aqueous solutions can contain more than one cation or anion

B) the anions precipitated as solid metals

C) the solubility of cations were decreased by the other cations

D) the solubility product of a compound was exceeded

Answer 54

[D] The amount of substance that will dissolve in water is described by the K_sp. If the amount of compound present is in excess of the K_sp, then a precipitate would form to maintain the K_sp

Question 55

Why would temperature fall as a balloon rises?

A) The work done on the gas by the water pressure decreases its temperature

B) The work done by the gas in expanding decreases its internal energy

C) The balloon and water exchange heat, increasing the temperature of the gas

D) The compression of the gas decreases its temperature

Answer 55

[B] As the balloon rises, temperature falls so it must decrease its internal energy as it decreases its pressure.

Question 56

A sparingly soluble metal hydroxide, M(OH)₂ has a molar solubility of S mol/L at 25ºC. Its K_sp value is:

A) S²

B) 2S²

C) 2S³

D) 4S³

Answer 56

[D] K_sp = [M][OH-]² so [S][2S]² is equal to 4S³

Question 57

When 2I- and S₂O₈^2- interact, they form I₂ and 2SO₄^2-. Students use starch as an indicator to detect the excess I₂ that accumulated as S₂O₃^2- was used up. The solution turned dark blue when starch and I₂ combined. So, students prepared two solutions:

Solution A contained KI and Na₂S₂O₃

Solution B contained (NH₄)₂S₂O₈ and starch.

The results of the experiment would most likely NOT be affected if the students had added excess:

A) KI to Solution A

B) Na₂S₂O₃ to Solution A

C) (NH₄)S₂O₈ to Solution B

D) Starch to solution B

Answer 57

[D] Starch is not a participant in any of the reactions, acting only as an indicator of excess I₂

Question 58

Which of the following statements is consistent with the incorrect conclusion that HCl is an ionic compound?

A) It is a gas at room temperature

B) A 1 M solution freezes below 0ºC

C) A 1 M solution conducts electricity

D) It is composed of two nonmetals

Answer 58

[C] Ionic compounds conduct electricity

Question 59

With respect to bonding and electrical conductivity, respectively, sulfur hexafluoride SF₆(g) would be described as:

A) covalent and a nonconductor

B) ionic and a nonconductor

C) covalent and conductor

D) ionic and conductor

Answer 59

[A] Covalent compounds are comprised of nonmetallic elements whereas binary ionic compounds are made up of a metal and a nonmetal. Covalent compounds do not conduct electricity.

Question 60

At which electrode is the aluminum produced in this reaction

2Al₂O₃ -> 4Al + 3O₂

in a galvanic cell and in an electrolytic cell?

A) At the anode in both cells

B) At the cathode in both cells

C) At the anode in the galvanic cell and cathode in the electrolytic cell

D) At the cathode in the galvanic cell and anode in the electrolytic cell

Answer 60

[B] Reduction of the Al³⁺ to form Al occurs at the cathode in both a galvanic and electrolytic cell.

Question 61

In the reaction shown in this equation:

Al(OH)₃ + NaOH -> Na[Al(OH)₄]

Al(OH)₃ acts as what kind of acid or base?

A) Lewis acid

B) Lewis base

C) Bronsted acid

D) Bronsted base

Answer 61

[A] The aluminum accepts an electron pair from the OH- of NaOH and is therefore acting as a Lewis acid.

Question 62

What is the electron configuration of chlorine in NaCl? (Chlorine has 17 protons)

A) 1s²2s²2p⁶3s²3p⁴

B) 1s²2s²2p⁶3s²3p⁵

C) 1s²2s²2p⁶3s²3p⁶

D) 1s²2s²2p⁶3s²3p⁴4s²

Answer 62

[B] In NaCl, chlorine exists as the chloride ion. A chloride ion has 18 electrons with the electron configuration. 1s²2s²2p⁶3s²3p⁶

Question 63

Which compound evaporates the fastest?

A) MTBE (Vapor pressure = 25 torr)

B) ETOH (Vapor pressure = 58 torr)

C) ETBE (Vapor pressure = 20 torr)

D) TAME (Vapor pressure = 15 torr)

Answer 63

[B] The greater the vapor pressure, the greater the rate of evaporation.

Question 64

The disposal of waste chemical is a common laboratory problem. An experiment to determine the copper content of a penny produces a waste mixture at pH 9 containing copper and zinc in the form of soluble complex ions of ammonia and solid hydroxides.

Given this equation:

Cu(NH₃)₄²⁺(aq) <-> Cu²⁺(aq) + 4NH₃

The oxidation state of copper in going from the penny to the waste mixture changes from:

A) 0 to +2

B) 0 to +1

C) +1 to 0

D) +2 to 0

Answer 64

[A] Copper metal in the penny has an oxidation state of 0. The waste mixture, Cu(NH₃)₄²⁺ has an oxidation state of +2.

Question 65

What is the formula for zinc(II) sulfide?

A) Zn₂S

B) ZnS

C) ZnS₂

D) Zn₂S₃

Answer 65

[B] Zinc has a charge of +2 and Sulfide has a charge of –2

Question 66

The literature value for the K_sp shown in this reaction

Zn(OH)₂(s) <-> Zn²⁺ + 2OH-

is determined by the value of:

A) [Zn²⁺][OH-]² in a saturated solution

B) [Zn²⁺][OH-] in an unsaturated solution

C) [Zn²⁺][OH-] in a saturated solution

D) [Zn²⁺][OH-]² in an unsaturated solution

Answer 66

[A] The K_sp of a salt is the equilibrium constant for the dissolution of that salt. It describes a saturated solution in which the aqueous ions are in equilibrium with the solid.

Question 67

After an acid treatment, metals exist as aqueous ions in an acidic solution from which they can be precipitated as insoluble sulfides by the addition of sodium sulfide. The solubility product constants for copper(II) and zinc(II) sulfides are 6.7 x 10^-42 and 1 x 10^-27,respectively.

Is the procedure more effective for zinc or copper?

A) Zinc, because its K_sp > K_sp of copper sulfide

B) Zinc, because its K_sp < K_sp of copper sulfide

C) Copper, because its K_sp > K_sp of zinc sulfide

D) Copper, because its K_sp < K_sp of zinc sulfide

Answer 67

[D] Copper(II) Sulfide would be less soluble with its lower K_sp value, and therefore the treatment would be more effective.

Question 68

The structure and bonding of diamond, which is formed from graphite at extreme pressures, should be similar to that of elemental:

A) aluminum and gallium

B) silicon and germanium

C) phosphorous and arsenic

D) sulfur and selenium

Answer 68

[B] At extreme pressures, an elemental solid assumes the structure and bonding characteristics of a heavier element in the same column of the periodic table. The structure and bonding of diamond, which is a form of carbon, would be like most other elements in its group which contains silicon and germanium.

Question 69

What bonding accounts for the expected increase in energy density of solid nitrogen as compared to methanol?

A) solid nitrogen contains covalent and ionic bonds; methanol contains only weak ionic bonds

B) solid nitrogen contains covalent and ionic bonds; methanol has covalent bonds within each molecule and weak van der Waal’s interactions between molecules

C) solid nitrogen contains only covalent bonds; methanol contains only weak ionic bonds

D) solid nitrogen contains only covalent bonds; methanol has covalent bonds within each molecule and weak intermolecular interactions

Answer 69

[D] Solid nitrogen contains only covalent bonds. Methanol contains only covalent bonds, but it can do intermolecular hydrogen bonding because of the –OH group

Question 70

What are the oxidizing and reducing agents, respectively, in the reaction below?

2HCl + H₂O₂ + MnO₂ à O₂ + MnCl₂ + 2H₂O

A) H₂O₂; HCl

B) H₂O₂; MnO₂

C) MnO₂; HCl

D) MnO₂; H₂O₂

Answer 70

[D] In the reaction, Mn is reduced from +4 to +2; therefore, MnO₂ is the oxidizing agent. O is oxidized from -1 to H₂O₂ to 0 in O₂, therefore H₂O₂ is the reducing agent.

Question 71

The maximum mass of H₂ that would be expected to form by the reaction of 6.54 g Zn with 50.0 mL of 0.1 M HCl is equal to which of the following?

A) 0.0025 g

B) 0.005 g

C) 0.1 g

D) 0.2

Answer 71

[B] The balanced reaction is: Zn(s) + 2HCl(aq) –> H₂(g) + ZnCl₂(aq). There is a limiting reagent question, so the number of moles of HCl is found by multiplying the volume in liters (0.05 L) by the concentration (0.1 mol / L) which is 0.005 moles HCl. The number of moles of zinc is 0.1 mol. So the limiting reagent is HCl. So: 0.005 mol HCl x 1 mol H₂ / 2 mol HCl x 2 g H₂ / 1 mol H₂ = 0.005 g H₂.

Question 72

What is the angular momentum number (l) for the orbital from which a Mg atom loses two electrons to form a Mg²⁺ ion

A) 0

B) 1

C) 2

D) 3

Answer 72

[A] The angular momentum quantum number dictates the shape of the orbital. It is the same as the number of angular nodes. When l = 0, the electron configuration is s. When l = 1, the electron configuration is p. When l = 2, the electron configuration is d. When l = 3, the electron configuration is f.

Question 73

The pressure inside a sealed 3-L tank containing 25 g of which product would be the highest at 300 K? (Assume no condensation)

A) CO₂

B) H₂O

C) N₂

D) O₂

Answer 73

[B] According to the Ideal Gas Law, pressure and moles of gas are directly proportional to each other. As one increases, so does the other. The gas sample that will exert the highest pressure is the same on that contains the most molecules or the most moles which is H₂O

Question 74

The average bond energies in kJ/mol of the C-H, C-O, C-C, and O-N single bonds present in nitroglycerin are 413, 358, 347, and 201, respectively. Which single bond present in nitroglycerin is most likely the shortest?

A) C-H

B) C-O

C) C-C

D) O-N

Answer 74

[A] The highest bond energy has the lowest bond length