Chemistry 2

Which of these species is a Lewis acid, but not a Brønsted acid?

HCN CO32− OH− Cl− **Al3+***

Which one of these equations represents the reaction of a weak acid with a weak base?

HCN(aq) + CH3NH2(aq) → CH3NH3+(aq) + CN−(aq)****

In which one of the following solutions will acetic acid have the greatest percent ionization?

***0.1 M CH3COOH*** 0.1 M CH3COOH dissolved in 0.1 M HCl 0.1 M CH3COOH dissolved in 0.2 M HCl 0.1 M CH3COOH plus 0.1 M CH3COONa 0.1 M CH3COOH plus 0.2 M CH3COONa

In which one of the following solutions will acetic acid have the greatest percent ionization?

**0.1 M CH3COOH** 0.1 M CH3COOH dissolved in 1.0 M HCl 0.1 M CH3COOH plus 0.1 M CH3COONa 0.1 M CH3COOH plus 0.2 M CH3COONa

Which one of the following is a buffer solution?

**0.40 M HCN and 0.10 KCN**** 0.20 M CH3COOH 1.0 M HNO3 and 1.0 M NaNO3 0.10 M KCN 0.50 M HCl and 0.10 NaCl

In the complex ion , the oxidation number of Fe is

+2

In the complex ion[Fe(CN)6]^4- , the oxidation number of Fe is

+2

In the complex ion [Co(en)2Br2]+, the oxidation number of Co is

+3

One liter of an aqueous solution contains 6.02 × 1020 H3O+ ions. Therefore, its H3O+ ion concentration is

0.00100 mole per liter.*****

Consider the reaction N2(g) + O2(g) <> 2NO(g), for which Kc = 0.10 at 2,000ºC. Starting with initial concentrations of 0.040 M of N2 and 0.040 M of O2, determine the equilibrium concentration of NO.

0.011 M**

Which of the following is the most acidic solution?

0.10 M CH3COOH and 0.10 M CH3COONa 0.10 M CH3COOH *0.10 M HNO2**** 0.10 M HNO2 and 0.10 M NaNO2 0.10 M CH3COONa

Calculate Kc for the reaction 2HI(g) <<>>> H2(g) + I2(g) given that the concentrations of each species at equilibrium are as follows: [HI] = 0.85 mol/L, [I2] = 0.60 mol/L, [H2] = 0.27 mol/L.

0.22

Polonium-208 is an alpha emitter with a half-life of 2.90 years. How many milligrams of polonium from an original sample of 2.00 mg will remain after 8.00 years?

0.296 mg***

What is the pH of a solution prepared by mixing 50.0 mL of 0.300 M HCl with 450.0 mL of 0.400 M HIO3? [Ka(HIO3) = 1.6 × 10−1]

0.89

Complete and balance the following redox equation using the smallest whole-number coefficients. What is the coefficient of Sn in the balanced equation? Sn + HNO3 → SnO2 + NO2 + H2O (acidic solution)

1

The solubility of lead(II) iodide is 0.064 g/100 mL at 20oC. What is the solubility product for lead(II) iodide?

1.1 × 10−8****

The solubility product for chromium(III) fluoride is Ksp = 6.6 × 10−11. What is the molar solubility of chromium(III) fluoride?

1.2 × 10−3 M****

Calculate Kp for the reaction 2NOCl(g) <<>>> 2NO(g) + Cl2(g) at 400°C if Kc at 400°C for this reaction is 2.1 × 10−2.

1.2***

The Ksp for silver(I) phosphate is 1.8 × 10−18. Calculate the molar solubility of silver(I) phosphate.

1.6 × 10−5 M*****

The molar solubility of manganese(II) carbonate is 4.2 × 10−6 M. What is Ksp for this compound?

1.8 × 10−11***

What is the OH− ion concentration in a 5.2 × 10−4 M HNO3 solution?

1.9 × 10−11 M***

Carbon-11 is a radioactive isotope of carbon. Its half-life is 20.3 minutes. What fraction of the initial number of carbon-11 atoms in a sample will remain after 81 minutes?

1/16**

What fraction of radioactive atoms remains in a sample after six half-lives?

1/64**

Calculate the pH of a 0.021 M NaCN solution. [Ka(HCN) = 4.9 × 10−10]

10.82

What is the pH at the equivalence point in the titration of 100 mL of 0.10 M HCN (Ka = 4.9 × 10−10) with 0.10 M NaOH?

11.0

Calculate the pH of 2.6 × 10−2 M KOH.

12.41

What is the pH of a 0.014 M Ca(OH)2 solution?

12.45

Calculate the pH of a 6.71 × 10−2 M NaOH solution

12.83***

Complete and balance the following redox equation using the set of smallest whole-numbers coefficients. What is the sum of the coefficients? HI + HNO3 → I2 + NO (acidic solution)

17

Complete and balance the following redox equation. Br2 → BrO3− + Br− (basic solution) The sum of the smallest whole-number coefficients is

18

How many 3d electrons does a V 3+ ion have?

2

How many unpaired electrons are there in the complex ion ? [Mn(Cn)6]^3-

2

What is the coordination number of silver in [Ag(NH3)2]Cl

2

The following reactions occur at 500 K. Arrange them in order of increasing tendency to proceed to completion (least → greatest tendency). 1. 2NOCl<<>>>2NO + Cl2 Kp = 1.7 x 10 -2 2. 2SO3<<<>>>2SO2 + O2 Kp = 1.3 x 10 -5 3. 2NO2<<<>>>2NO + O2 Kp = 5.9 x 10 -5

2 < 3 < 1

Consider an electrochemical cell constructed from the following half cells, linked by a KCl salt bridge. • an Al(s) electrode in 0.5 M Al2(SO4)3 solution • a Pb(s) electrode in 1.0 M Pb(NO3)2 solution Which electrode is the anode?

Al****

The OH− concentration in a 1.0 × 10−3 M Ba(OH)2 solution is

2.0 × 10−3 M.**

Calculate E°cell for a silver-aluminum cell in which the cell reaction is Al(s) + 3Ag+(aq) → Al3+(aq) + 3Ag(s)

2.46 V****

Consider the weak acid CH3COOH (acetic acid). If a 0.048 M CH3COOH solution is 5.2% ionized, determine the [H3O+] concentration at equilibrium.

2.5 × 10−3 M**

Calculate the silver ion concentration in a saturated solution of silver(I) carbonate (Ksp = 8.1 × 10−12).

2.5 × 10−4 M******

Calculate the hydrogen ion concentration in a solution having a pH of 4.60.

2.5 × 10−5 M***

What is the pH of 10.0 mL of 0.0020 M HCl?

2.70

If 12% of a certain radioisotope decays in 5.2 years, what is the half-life of this isotope?

28 year

Complete and balance the following redox equation. What is the coefficient of H2O when the equation is balanced using the set of smallest whole-number coefficients? MnO4− + SO32− →Mn2+ + SO42− (acidic solution)

3

On analysis, an equilibrium mixture for the reaction 2H2S(g) <<<>>> 2H2(g) + S2(g) was found to contain 1.0 mol H2S, 4.0 mol H2, and 0.80 mol S2 in a 4.0 L vessel. Calculate the equilibrium constant, Kc, for this reaction.

3.2

Calculate the concentration of chromate ion (CrO42−) in a 0.450 M solution of chromic acid (H2CrO4). [For chromic acid, Ka1 = 0.18, Ka2 = 3.2 × 10-7.]

3.2 × 10-7 M***

The molar solubility of magnesium carbonate is 1.8 × 10−4 mol/L. What is Ksp for this compound?

3.2 × 10−8***

50.00 mL of 0.10 M HNO2 (nitrous acid, Ka = 4.5 × 10−4) is titrated with a 0.10 M KOH solution. After 25.00 mL of the KOH solution is added, the pH in the titration flask will be

3.35

What is the pH of a 0.0055 M HA (weak acid) solution that is 8.2% ionized?

3.35

The measured voltage of the cell Pt(s) | H2 (1.0 atm) | H+(aq) || Ag+(1.0 M) | Ag(s) is 1.02 V at 25°C. Calculate the pH of the solution

3.72***

Calculate the pH of a buffer solution prepared by dissolving 0.20 mole of cyanic acid (HCNO) and 0.80 mole of sodium cyanate (NaCNO) in enough water to make 1.0 liter of solution. [Ka(HCNO) = 2.0 × 10−4]

4.30

A typical radius of an atomic nucleus is about

5 × 10−3 pm***

You have 500.0 mL of a buffer solution containing 0.20 M acetic acid (CH3COOH) and 0.30 M sodium acetate (CH3COONa). What will the pH of this solution be after the addition of 20.0 mL of 1.00 M NaOH solution? [Ka = 1.8 × 10−5]

5.07

Calculate the pH at the equivalence point for the titration of 0.20 M HCl with 0.20 M NH3 (Kb = 1.8 × 10−5).

5.12

1.25 moles of NOCl were placed in a 2.50 L reaction chamber at 427ºC. After equilibrium was reached, 1.10 moles of NOCl remained. Calculate the equilibrium constant, Kc, for the reaction 2NOCl(g) <<<>>>> 2NO(g) + Cl2(g).

5.6 × 10−4

The solubility of strontium carbonate is 0.0011 g/100 mL at 20oC. Calculate the Ksp value for this compound.

5.6 × 10−9****

Calculate the H+ ion concentration in a 8.8 × 10−4 M Ca(OH)2 solution.

5.7 × 10-12 M**

The total number of electrons in the 3d orbital of Co^{3+} is

6

What is the pH at the equivalence point in the titration of 100 mL of 0.10 M HCl with 0.10 M NaOH?

7.0

A solution is prepared by mixing 500. mL of 0.10 M NaOCl and 500. mL of 0.20 M HOCl. What is the pH of this solution? [Ka(HOCl) = 3.2 × 10−8]

7.19

The brown gas NO2 and the colorless gas N2O4 exist in equilibrium, 2NO2 <<<>>>> N2O4. In an experiment, 0.625 mole of N2O4 was introduced into a 5.00 L vessel and was allowed to decompose until equilibrium was reached. The concentration of N2O4 at equilibrium was 0.0750 M. Calculate Kc for the reaction.

7.5

A 0.10 M HF solution is 8.4% ionized. Calculate the H+ ion concentration.

8.4 × 10−3 M**

Calculate the pH of the solution resulting from the addition of 10.0 mL of 0.10 M NaOH to 50.0 mL of 0.10 M HCN (Ka = 4.9 × 10−10) solution.

8.71

Which of these statements is true about chemical equilibria in general?

At equilibrium the total concentration of products equals the total concentration of reactants, that is, [products] = [reactants]. Equilibrium is the result of the cessation of all chemical change. There is only one set of equilibrium concentrations that equals the Kc value. At equilibrium, the rate constant of the forward reaction is equal to the rate constant for the reverse reaction. ***At equilibrium, the rate of the forward reaction is equal to as the rate of the reverse reaction.***

Identify the conjugate base of HClO3 in the reaction ClO3− + HSO4− <---> HClO3 + SO42−

ClO3−**

The equilibrium constant expression for the reaction 2BrF5(g)<<>>>Br2(g) + 5F2(g) is

Kc = [Br2] [F2]5/[BrF5]2***

Which is the correct equilibrium constant expression for the following reaction? Fe2O3(s) + 3H2(g) <<>> 2Fe(s) + 3H2O(g)

Kc = [H2O]3/[H2]3***

The reaction 2SO3(g) <<>> 2SO2(g) + O2(g) is endothermic. If the temperature is increased,

Kc will increase.***

Charcoal found under a stone at Stonehenge, England, has a carbon-14 activity that is 0.60 that of new wood. How old is the charcoal? (The half-life of carbon-14 is 5,730 years.)

Less than 5,730 yr***

For the following reaction at equilibrium in a reaction vessel, which one of these changes would cause the Br2 concentration to increase? 2NOBr(g) <<>>>> 2NO(g) + Br2(g), ΔHºrxn= 30kJ/mol

Lower the temperature. ***Remove some NO.*** Remove some NOBr. Compress the gas mixture into a smaller volume.

Iron objects such as storage tanks and underground pipelines can be protected from corrosion by connecting them through a wire to a piece of

Mg

Which one of the following reactions will occur spontaneously at standard-state conditions and 25°C?

Mg2+ + Ca →Mg + Ca2+****

Which choice lists all of the following species that can oxidize H2O to O2(g) under standard-state conditions? (2H2O(l) → O2(g) + 4H+(aq) + 4e−) MnO4−(aq), Cl2(g), Pb2+(aq), Cl− (aq), Ag+(aq)

MnO4−(aq) and Cl2(g)****

Which of these situations will result if some CH4(g) is removed from the reaction CO(g) + 3H2(g) <<<>>>>CH4(g) + H2O(g) at equilibrium?

More CH4 and H2O will be produced.**

Which of the following yields a basic solution when dissolved in water?

NO2 P4O10 **K2O** NaCl SO2

According to the following cell diagram, which chemical species undergoes reduction? Sn | Sn2+ || NO3− (acid soln), NO(g) | Pt

NO3−***

In the following half equation, which is the oxidizing agent? NO3−(aq) + 4H+(aq) + 3e− → NO(g) + 2H2O

NO3−***

Which one of the following reagents is capable of transforming Cu2+(1 M) to Cu(s)?

Ni(s)***

At 700 K, the reaction 2SO2(g) + O2(g) 2SO3(g) has the equilibrium constant Kc = 4.3 × 106, and the following concentrations are present: [SO2] = 0.010 M; [SO3] = 10.M; [O2] = 0.010 M. Is the mixture at equilibrium? If not at equilibrium, in which direction (as the equation is written), left to right or right to left, will the reaction proceed to reach equilibrium?

No, right to left***

When an aqueous solution of AgNO3 is electrolyzed, a gas is observed to form at the anode. The gas is

O2.***

Consider a buffer solution prepared from HOCl and NaOCl. Which is the net ionic equation for the reaction that occurs when NaOH is added to this buffer?

OH− + HOCl → H2O + OCl−****

Identify the conjugate base of HPO42− in the reaction HCO3− + HPO42− <---> H2CO3 + PO43−

PO43-***

Which of these metals will reduce water to hydrogen in basic solution under standard conditions?

Pb Fe Zn **Na*** Ag

What element is the stable end-product of the uranium radioactive decay series?

Pb*

A radioisotope decays to give an alpha particle and Pb-208. What was the original element?

Po*

When the following reaction is at equilibrium, which of these relationships is always true? 2NOCl(g) <<>>2NO(g) + Cl2(g)

[NO]2[Cl2] = Kc[NOCl]2***

Aluminum does not corrode as does iron, because

a protective layer of Al2O3 forms on the metal surface.****

Consider this reaction at equilibrium: 2SO2(g) + O2(g) <<>>>2SO3(g), ΔHºrxn = −198 kJ/mol If the volume of the system is compressed at constant temperature, what change will occur in the position of the equilibrium?

a shift to produce more SO3***

A titration of an acid and base to the equivalence point results in a noticeably acidic solution. It is likely this titration involves

a strong acid and a weak base****

The only stable isotope of iodine is iodine-127. Predict the mode of decay of 130-53

beta emission***

What role does cadmium metal (Cd) play in a nuclear reactor?

controls chain reaction (control rods)**

When the substances in the equation below are at equilibrium, at pressure P and temperature T, the equilibrium can be shifted to favor the products by CuO(s) + H2(g) <<>>> H2O(g) + Cu(s) ΔHºrxn = −2.0 kJ/mol

decreasing the temperature.***

Which of the following is an advantage of nuclear power plants over coal-burning plants? Nuclear power plants

do not pollute the air with SO2, soot, and fly-ash.***

Beta particles are identical to

electrons

Which type of nuclear process requires an extremely high temperature (millions of degrees)?

fusion reaction***

Which is the most penetrating of the three types of nuclear radiation?

gamma***

A bidentate ligand always

has two donor atoms.***

Alpha particles are identical to

helium nuclei.****

The pH at the equivalence point of a titration may differ from 7.0 due to

hydrolysis of the salt formed.****

Decay of tin-110 by electron capture yields

indium-110.

Gamma-rays cause radiation damage when they interact with matter by producing

ions and free radicals.***

The energy released by the sun is the result of

nuclear fusion**

As a result of beta decay, the product nucleus is

one atomic number higher than the original element.**

Over what range of pH is a HOCl − NaOCl buffer effective?

pH 6.5 - pH 8.5*****

For the reaction at equilibrium 2SO3 <<>> 2SO2 + O2 (ΔHºrxn= 198 kJ/mol), if we increase the reaction temperature, the equilibrium will

shift to the right.***

For the reaction Ni2+(aq) + 2Fe2+(aq) → Ni(s) + 2Fe3+(aq), the standard cell potential E°cell is

−1.02 V.****

Calculate the value of E°cell for the following reaction: 2Au(s) + 3Ca2+(aq) → 2Au3+(aq) + 3Ca(s)

−4.37 V***

Which of these metals will not be oxidized in hydrochloric acid under standard conditions at 25°C?

Ag

Which of the following species is the strongest oxidizing agent under standard-state conditions?

Ag+(aq) H2(g) H+(aq) ***Cl2(g)**** Al3+(aq)

Which of the following ligands produces the weakest crystal field?

Br-

Which of the following is a monodentate ligand?

CN-

Which of the following ligands produces the strongest crystal field?

CN-

Which one of the following statements about fission and fusion is false?

For a fission reaction the mass defect (Δm) is negative, whereas for fusion Δm is positive.*****

What is the net ionic equation for the reaction that occurs when small amounts of hydrochloric acid are added to a HOCl/NaOCl buffer solution?

H+ + OCl− → HOCl***

What is the net ionic equation for the reaction that occurs when small amounts of hydrochloric acid are added to a HOCl/NaOCl buffer solution?

H+ + OCl− → HOCl****

Predict the products of the electrolysis of aqueous aluminum bromide AlBr3(aq). (Balancing is not required.)

H2 + OH− + Br2**

Given the following notation for an electrochemical cell Pt(s) | H2(g) | H+(aq) || Ag+(aq) | Ag(s), what is the balanced overall (net) cell reaction?

H2(g) + 2Ag+(aq) → 2H+(aq) + 2Ag(s)***

Identify the conjugate acid of HCO3− in the reaction HCO3− + HPO42− <---> H2CO3 + PO43−

H2CO3****

Which of these lists of molecules is arranged in order of increasing acid strength?

H2S < H2O < H2Se ***H2O < H2S < H2Se*** H2Se < H2O < H2S H2S < H2Se < H2O H2O < H2Se < H2S

Acid strength decreases in the series HI > HSO4− > HF > HCN. Which of these anions is the weakest base?

I−***

For the following reaction at equilibrium, which choice gives a change that will shift the position of equilibrium to favor formation of more products? 2NOBr(g) <<>>>2NO(g) + Br2(g), ΔHºrxn = 30 kJ/mol

Increase the total pressure by decreasing the volume. Add more NO. *** Remove Br2.** Lower the temperature. Remove NOBr selectively.

Consider this gas phase equilibrium system: PCl5(g) <<>>>PCl3(g) + Cl2(g) ΔHºrxn = +87.8 kJ/mol. Which of these statements is false?

Increasing the system volume shifts the equilibrium to the right. Increasing the temperature shifts the equilibrium to the right. **A catalyst speeds up the approach to equilibrium and shifts the position of equilibrium to the right.** Decreasing the total pressure of the system shifts the equilibrium to the right. Increasing the temperature causes the equilibrium constant to increase.

Acid strength decreases in the series: strongest HSO4− > HF > HCN. Which of these species is the weakest base?

SO42−****

Identify the conjugate base of HSO4 - in the reaction H2PO4− + HSO4− <---> H3PO4 + SO42−

SO42−****

Will a precipitate (ppt) form when 20.0 mL of 1.1 × 10−3 M Ba(NO3)2 are added to 80.0 mL of 8.4 × 10−4 M Na2CO3?

Yes, the ppt is BaCO3.***

Which of these metals will be oxidized in hydrochloric acid under standard conditions at 25°C?

Zn

A certain electrochemical cell has for its cell reaction: Zn + HgO → ZnO + Hg Which is the half-reaction occurring at the anode?

Zn → Zn2+ + 2e−****

Which one of the following reactions must be carried out in an electrolytic cell rather than in an electrochemical cell?

Zn2+ + Ca → Zn + Ca2+ *** Al3+ + 3Br− → Al + (3/2)Br2**** 2Al + 3Fe2+ → 2Al3+ + 3Fe H2 + I2(s) → 2H+ + 2I−

The electron configuration of a Cr3+

[Ar]3d3

The electron configuration of a Mn atom is

[Ar]4s23d5