Chem Test 75 Multiple Choice

A beaker contains 300ml of a .2 M Pb(NO3)2 solution. If 200ml of a .2M solution of MgCl2 is added to the beaker, what will be the final concentration of Pb2+ ions in the resulting solution?

B) 0.040 M

When excess hydroxide ions were added to a 1 liter of CaCl2 solution, Ca(OH)2 precipitate was formed. IF all calcium ions were precipitated in 7.4g of Ca(OH)2, what was the initial concentration of the CaCl2 solution?

B) 0.10-molar

The first ionization energy for magnesium is 730 kj/mol. The third IE for magnesium is 7700 kj/mol. What is the most likely value for magnesium's second ionization energy?

B) 1,400 kj/mol

In which of the following equilibria would the concentrations of the products be increased if the volume of the system were decreased at constant temperature?

B) 2CO + O2 -><- 2CO3 If volume decreases, will shift to side with fewest moles. Which is right.

A student placed solid barium oxalate in water and allowed it to come to equilibrium with its dissolved ions. The student then added a nickel (ii) nitrate solution to the beaker to create BaC2O4 + Na2+ -><- Ba2+ + NiC2O4 If solubility for BaC2O4 = 2 * 10 ^-7, and solubility for NiC2O4 = 4*10^-10, what is equilibrium constant?

B) 5*10^2

11. A solution prepared by mixing equal volumes of 0.2-molar HCl and 0.2-molar NH3

B) A solution with a pH of greater than 1 and less than 7. HCl - strong. NH3 - weak.

Which of the following experimental procedures is used to separate two substances by taking advantage of their differing boiling points?

B) Distillation

This molecule contains no pi bonds

B) H2O (no double bonds)

In this molecule, oxygen forms sp3 hybrid orbitals.

B) H2O (oxygen is central atom)

H2 + I2 -> 2HI At 450 C the equilibrium constant, K, for the reaction shown above has a value of 50. Which of the following sets of initial conditions at 450 C will cause the reaction to produce more H2?

B) II only II. [HI] = 10-molar, [H2] = 1-molar, [I2] = 2-molar

Which of the following can be determined directly from the difference between the boiling point of a pure solvent and the boiling point of a solution of a nonionic solute in the solvent, if kb for the solvent is unknown?

B) II only. II. the molality of the solution m = ^T/kb

A solution to be used as a reagent for a reaction is to be removed from a bottle marked with its concentration. Which fo the following is NOT part of the proper procedure for this process?

B) Inserting a pipette directly into the bottle and drawing out the solution. Could contaminate it.

Which of the following sets of gases would be most difficult to separate if the method of gaseous effusion is used?

B) N2 and C2H4. Both 28, can't effuse because equal.

Which of the following statements is true regarding sodium and potassium?

B) Sodium has a larger first ionization energy and a small atomic radius.

A student examined 2.0 moles of an unknown carbon compound and found that the sample contained 48 grams of carbon, 64 grams of oxygen, and 8 grams of hydrogen. Which of the following could be the molecular formula of the compound?

C) CH3COOH

The molecular formula for hydrated iron (iii) oxide, or rust, is generally written as Fe2O3 * xH2O because the water content in rust can vary. If a 1-molar sample of hydrated iron (iii) oxide is found to contain 108g of H2O, what is the molecular formula for the sample?

C) Fe2O3 * 6H2O 108g H2O / 18g = 6mol

How many moles of KCl must be added to 200 milliliters of a .5-molar NaCl solution to create a solution in which the concentration of Cl- ion is 1-molar.

A) .1 moles

HCl + AgNO3 -> AgCl + HNO3 One-half liter of a .2-molar HCl solution is mixed with one-half liter of a .4-molar solution of AgNO3. A reaction occurs forming a precipitate as shown above. If the reaction goes to completion, what is the mass of AgCl produced?

A) 14 grams

An atom that has this ground-state electron configuration will have the smallest atomic radius of those listed above.

A) 1s2 2s2 2p6

A mixture of gases at equilibrium over water at 43 C contains 9.0 moles of nitrogen, 2.0 moles of oxygen, and 1.0 moles of water vapor. if the total pressure exerted by the gases is 780 mmHg, what is the vapor pressure of water at 43 C?

A) 65 mmHg

A solution prepared by mixing equal volumes of 0.2-molar HCl and 0.2-molar NaCl.

A) A solution with a pH of 1

A 100ml sample of 0.10 molar NaOH solution was added to 100ml of 0.10 molar H3.C6.H5.O7. After equilibrium was established, which of the ions listed below was present in the greatest concentration?

A) H2.C6.H5.O7-

N2 + 3H2 -><- 2NH3 + energy Which of the following changes to the equilibrium situation shown above will bring about an increase in the number of moles of NH3 present at equilibrium?

A) I only I. Adding N2 gas to the reaction chamber.

The addition of a catalyst to a chemical reaction will bring about a change in which of the following characteristics of the reaction?

A) I only I. The activation energy

Which of the following equilibrium expressions represents the hydrolysis of the CN- ion.

A) K= [HCN][OH-]/[CN-]

This is the most exothermic reaction

A) Reactants top left. Products bottom right.

The value of the equilibrium constant Keq is greater than 1 for a certain reaction under standard state conditions. Which of the following statements must be true regarding the reaction?

A) ^G is negative. ^G = -Rt * lnK

2NO + O2 -> 2NO2 The reaction above occurs by the following two-step process: Which of the following is true of Step II if it is the rate-limiting step?

B) Step II has a higher activation energy and occurs more slowly than step 1. Slow because has to go through high activation energies.

The density of a sample of water decreases as it is heated above a temperature of 4 C. Which of the following will be true of an aqueous solution of NaC2H3O2 when it is heated from 10 C to 60 C.

B) The molarity will decrease d = g/L

If the pressure of the substance shown in the diagram is decreased from 1.0 atmosphere to 0.5 atmosphere at a constant temperature of 100 C, which phase change will occur?

B) Vaporization Liquid - Gas

A sample of an ideal gas confined in a rigid 5.00 liter container has a pressure of 363 mmHg at a temperature of 25 C. Which of the following expressions will be equal to the pressure of the gas if the temperature of the container is increased to 35 C?

C) (363)(308)/(298) mmHg

Which of the following aqueous solutions has the highest boiling point?

C) 0.1 m Na2SO4 ^T = Kb * m. m = particles. 2:1, has 3 particles. All others only have 1:1, 2.

The ground state configuration of an atom of a paramagnetic element (uncompleted orbital)

C) 1s2 2s2 2p6 3s2 3p4

The nuclide 61/26 Fe decays through the emission of a single beta particle. What is the resulting nuclide?

C) 61/27Co 61/26Fe + 0/-1 -> 61/27

A solution prepared by mixing equal volumes of 0.2-molar HNO3 and 0.2-molar NaOH

C) A solution with pH of 7. Both are strong.

Which of the following pairs of compounds are isomers? (Same atoms arranged in different ways)

C) C2H5OH and CH3OCH3

Which of the following can function as both a Bronsted-Lowry acid and a Bronsted-Lowry base?

C) HSO3-

Which of the following statements regarding atomic theory is NOT true?

C) Heisenberg's uncertainty principle describes the equivalence of mass and energy. Says momentum and location fo electron unknown.

Which of the following procedures will produce a buffered solution?

C) I and II only I. Equal volumes of 1 M NH3 and 1 M NH4Cl solutions are mixed. II. Equal volumes of 1M H2CO3 and 1 M NaHCO3 solutions are mixed.

Under what conditions can all three phases of the substance shown in the diagram exist simultaneously in equilibrium

C) Pressure = 1.0 atm, temperature = 50 C

The reaction has the largest activation energy

C) Reactants bottom left. Products bottom right slightly above.

2MnO4- + 5SO32- + 6H+ -> 2Mn2+ + 5SO42- + 3H20 Which of the following statements is true regarding the reaction given above?

C) SO32- acts as the reducing agent.

Reactant A underwent a decomposition reaction. The concentration of A was measured periodically and recorded in the chart above. Based on the data in the chart, which of the following statements is NOT true?

C) The rate of the reaction is constant over time.

If the temperature at which a reaction takes place is increased, the rate of the reaction will

C) increased if the reaction is endothermic, and increase if the reaction is exothermic.

2ZnS + 3O2 -> 2ZnO + 2SO2 If the reaction above took place at STP, what was the volume of O2 required to product 50 grams of ZnO?

D) (40)(3)(22.4)/(81.4)(2)

H2 + Cl2 -> HCl Based on the information given in the table below, what is the ^H for the above reaction? H-H : Bond Energy 440 Cl-Cl : Bond Energy 240 H-Cl : Bond Energy 430

D) -180kj

+n -> 7/3Li + 4/2He For the nuclear reaction shown above, what is the missing reactant?

D) 10/5B 1/0n

A 100-gram sample of pure 37/18Ar decays by electron capture with a half-life of 35 days. How long will it take for 90 grams of 37/17Cl to accumulate?

D) 116 days. Both have molar mass of 37, so same life info.

The ground state configuration for both a potassium ion and a chloride ion.

D) 1s2 2s2 2p6 3s2 3p6

A pure sample of KClO3 is found to contain 71 grams of chlorine atoms. What is the mass of the sample?

D) 245 grams

When the half-reaction above is balanced, what is the coefficient for H+ if all the coefficients are reduced to the lowest whole number?

D) 8

C3H7OH + O2 -> 3CO2 + 4H2O One mole of C3H7OH underwent combustion as shown in the reaction above. How many moles of oxygen were required for the reaction?

D) 9/2 moles

A solution prepared by mixing equal volumes of 0.2-molar CH3COOH and 0.2-molar NaOH

D) A solution with a pH of greater than 7 and less than 13

When a solution of KMnO4 was mixed with a solution of HCl, Cl2 gas bubbles formed and Mn2+ ions appeared in the solution. Which of the following has occurred?

D) Cl- has been oxidized by MnO4-

This reaction has the largest positive value for ^H

D) Endothermic. Reactants bottom left. Products top right.

2NO + 2H2 -> N2 + 2H2O Which of the following is true regarding the relative molar rates of disappearance of the reactants and appearance of the products?

D) II and III only II. H2O appears at the same rate that NO disappears. III. NO disappears at the same rate that H2 disappears

Which of the following substances experiences the strongest attractive intermolecular forces?

D) NH3. Hydrogen bonding.

In which of the following reactions does the greatest increase in entropy take place?

D) NH4Cl -> NH3 + HCl. prod - react. 2-1 = 1

This molecule contains one unpaired electron

D) NO2

A boiling-water bath is sometimes used instead of a flame in heating objects. Which of the following could be an advantage of a boiling-water bath over a flame?

D) The temperature of boiling water remains constant at 100 C.

Which of the following salts will produce a colorless solution when added to water?

D) ZnSO4

SO42-, PO43-, ClO4- The geometries of the polyatomic ions listed above can all be described as.

D) tetrahedral

The boiling point of water is known to be lower at high elevations. This is because

D) the atmospheric pressure is lower at high elevations.

Based on the information above, what is the standard enthalpy change for the following reaction? 2SO2 + O2 -> 2SO3

E) 2y-2x (products - reactants)

Which of the following sets of quantum numbers (n, l, ml, ms) best describes the highest energy valence electron in a ground-state aluminum atom?

E) 3, 1, 1, 1/2 Because 3p

The acid dissociation constant for HClO is 3.0 * 10^-8. What is the hydrogen ion concentration in a 0.12M solution of HClO?

E) 6.0 * 10^-5 M

How much water must be added to 50.0 ml solution of 0.60 M HNO3 to produce a 0.40M solution of HNO3?

E) 75 ml

The solubility product, Ksp, of CaF2 is 4*10^-11. Which of the following expressions is equal to the solubility of CaF2?

E) Cube Root(1*10^-11) M

Oxygen has an oxidation state of zero in the molecule

E) O2

A chemist analyzed the carbon-carbon bond in C2H6 and found that it had a bond energy of 350 kj/mol and a bond length of 1.5 angstroms. If the chemist performed the same analysis on the carbon-carbon bond in C2H2, how would the results compare?

E) The bond energy for C2H2 would be greater, and the bond length would be shorter. C2H2 has triple bond. C2H6 has single.

CH4 + 2O2 -> CO2 + 2H2O If 16 grams of CH4 reacts with 16 grams of O2 in the reaction shown above, which of the following will be true?

E) The limiting reagent will be O2

Which of the following is true under any conditions for a reaction that is spontaneous at any temperature?

E) ^G and ^H are negative, and ^S is positive.