AP Chem Midterm

Which of the following is a weak acid in aqueous solution?

H2S

Which of the following salts is LEAST soluble?

NiS

When a buret is rinsed before a titration, which of the techniques is the best procedure?

Rince twice, once with the titration solution, then once with distilled water.

M+ is an unknown metal cation with a 1+ charge. A student dissolves the chloride of the unknown metal, MCl, in water to make it 100.0 mL of solution. The student then mixes the solution with excess AgNO3 solution, causing the AgCl to precipitate. The student collects the precipitate by filtration, dries it, and records the data shown below. (The molar mass of AgCl is 143 g/mol) Mass of Unknown Chloride, MCl: 0.74g Mass of Filter Paper: 0.80g Mass of Filter Paper plus AgCl precipitate: 2.23g

A

The figure above represents three sealed 1.0L vessels, each containing a different inert gas at 298K. The pressure of Ar in the first vessel is 2.0atm. The ratio of the numbers of Ar, Ne, and He atoms in the vessels is 2:1:6, respectively. After all the gases are combined in a previously evacuated 2.0L vessel, what is the total pressure of the gases at 298K? a) 3.0 atm b) 4.5 atm c) 9.0 atm d) 18 atm

B) 4.5 atm

36) The density of the gas, in g/L, is A) Greatest in container A B) Greatest in container B C) Greatest in container C D) The same in all 3 containers

B) Greatest in container B

What type of process occurs when solid sodium acetate, NaC2H302(s) is added to water?

Bronsted Lowry Acid-Base reaction

C3H8(g) + 4Cl2(g) -> C3H4Cl4(g) + 4HCl(g) A 6.0 mol sample of C3H8(g) and a 20. mol sample of Cl2(g) are placed in a previously evacuated vessel, where they react according to the equation above. After one of the reactants has been totally consumed, how many moles of HCl(g) have been produced? a) 4.0 mol b) 8.0 mol c) 20. mol d) 24 mol

C) 20. mol

A student mixes dilute AgNO3(aq) with excess NaCl to form AgCl(s), as represented by the net ionic equation above. Which of the diagrams below best represents the ions that are present in the significant concentration in the solution?

C, (2 NO3-, 2 Cl-, 4 Na+)

The elements I and Te have similar atomic masses. A sample that was believed to be a mixture of I and Te was run through a mas spectometer, resulting in the data above. All of the following statements are true. Which one would be the best bases for concluding that the sample was pure Te.

I consists of only one naturally occurring isotope with 74 neutrons, whereas Te has more than one isotope.

M+ is an unknown metal cation with a 1+ charge. A student dissolves the chloride of the unknown metal, MCl, in water to make it 100.0 mL of solution. The student then mixes the solution with excess AgNO3 solution, causing the AgCl to precipitate. The student collects the precipitate by filtration, dries it, and records the data shown below. (The molar mass of AgCl is 143 g/mol) Mass of Unknown Chloride, MCl: 0.74g Mass of Filter Paper: 0.80g Mass of Filter Paper plus AgCl precipitate: 2.23g What is the identity of the metal chloride? NaCl? CuCl? KCl? LiCl?

KCl

Na2O: 62g MgO: 40.3g K2O: 94.2g CaO: 56.1g According to the information in the table above, a 1.00g sample of which of the following contains the greatest mass of oxygen?

MgO

What type of process occurs when Al(s) and CuCl2(aq) are mixed?

Oxidation Reduction Reaction

M+ is an unknown metal cation with a 1+ charge. A student dissolves the chloride of the unknown metal, MCl, in water to make it 100.0 mL of solution. The student then mixes the solution with excess AgNO3 solution, causing the AgCl to precipitate. The student collects the precipitate by filtration, dries it, and records the data shown below. (The molar mass of AgCl is 143 g/mol) Mass of Unknown Chloride, MCl: 0.74g Mass of Filter Paper: 0.80g Mass of Filter Paper plus AgCl precipitate: 2.23g During the course of the experiment, which of the following happens to the NO3- ions?

They remain dissolved in the filtrate solution.

Which of the following is the best piece of lab glassware for preparing 500.0 mL of an aqueous solution of a solid?

Volumetric Flask

The mass percent of carbon in pure glucose, C6H12O6, is 40 percent. A chemist analyzes an impure sample of glucose and determines that the mass percent of carbon is 38.2 percent. Which of the following impurities could amount for the low mass percent of carbon in the sample?

Water, H20

Zn(s) is used to reduce other compounds in chemical reactions. If a chemist needs a substance that is more effective in its ability, which of the following species would be the best choice? a) Na b) H+ c) K+ d) Cl-

a) Na

5H2O2(aq) + 2MnO4-(aq) + 6H+(aq) -> 2Mn2+(aq) + 8H2O(l) + 5O2(g) In a titration experiment, H2O2(aq) reacts with aqueous MnO4-(aq) as represented by the equation above. The dark purple KMnO4 solution is added from a buret to a colorless, acidified solution of H2O2(aq) in an Erlenmeyer flask. Which element is being oxidized during the titration, and what is the element's change in oxidation number? a) Oxygen, which from changes -1 to 0 b) Oxygen, which from changes 0 to -2 c) Manganese, which changes from -1 to +2 d) Manganese, which changes from +7 to +2

a) Oxygen, which from changes -1 to 0

Container 1: He: 2.00atm: ?g Container 2: Ne: 2.00atm: ? Container 3: ?: 2.00atm: 16.0g Container 4: SO2: 1.96atm: 64.1g Under the circumstances given, consider 1,2, and 4 only. The average speed of the gas particles is ______. a) greatest in container 1 b) greatest in container 2 c) greatest in container 4 d) The same in containers 1,2, and 4.

a) greatest in container 1

Appropriate uses of a visible light spectrophotometer include which of the following i. Determining the concentration of a solution of Zn(NO2)2 ii. Measuring the conductivity of a solution of KMnO4 iii. Determining which ions are present in a solution that may contain Ni2+, Co2+, and Fe 3+ a) i only b) ii only c) iii only d) i and ii only e) i and iii only

a) i only

MnO4 + 5Fe2+ + 8H+ -> Mn2+ + 5Fe3+ +4H2O In the reaction represented above, the number of MnO4- ions that react must be equal to which of the following? a) one fifth the number of Fe2+ ions that are consumed b) Eight times the number of H+ ions that are consumed c) Five times the number of Fe3+ ions that are produced d) One-half the number of H2O molecules that are produced

a) one fifth the number of Fe2+ ions that are consumed

What is the maximum number of moles Al2O3 that can be produced by the reaction of .40 mol of Al with .40 mol of O2? a) .10 mol b) .20 mol c) .27 mol d) .33 mol e) .40 mol

b) .20 mol

The volume of water that must be added in order to dilute 40 mL of 9.0 M HCl to a concentration of 6.0 M is closest to a) 10 mL b) 20 mL c) 30 mL d) 40 mL e) 60 mL

b) 20 mL

Calcium: 194pm (atomic radius): 590kJ/mol (IE) Potassium: ? (atomic raidus): ? (IE) Based on the periodic trends and the data in the table above, which of the following are the most probable values of the atomic radius and the First Ionization energy for potassium, respectively? a) 242 pm, 633 kJ/mol b) 242 pm, 419 kJ/mol c) 120 pm, 633 kJ/mol d) 120 pm, 419 kJ/mol

b) 242 pm, 419 kJ/mol

How much energy is required to melt 64g of methane at 90K? a).24 kJ b) 3.8 kJ c) 33 kJ d) 60 kJ

b) 3.8 kJ

_Zn(s) + _H+(aq) + _NO3-(aq) -> _Zn2+(aq) + _NH4+(aq) + _H2O(l) When the equation above is balanced and all the coefficients are reduced to lowest whole number terms, the coefficient for Zn(s) is a)2 b)4 c)6 d)10 e)14

b) 4

2KClO3(s) -> 2KCl(s) + 3O2(g) What is the percentage yield of O2 if 12.3 g of KClO3 (molar mass 123g) is decomposed to produce 3.2g of O2 (molar mass 32g) according to the equation above? a) 100% b) 67% c) 50% d) 33% e) 10%

b) 67%

Which of the following statements about atoms is NOT correct? a) Atoms are electrically neutral because they have the same number of protons and electrons b) All the atoms of a given element must have the same number of protons, neurons, and electrons. c) Most of the volume of an atom contains only electrons d) The nucleus is positively charged e) Almost all of the mass of an atom is in the nucleus

b) All the atoms of a given element must have the same number of protons, neurons, and electrons.

A 100g sample of a metal was heated to 100C and then quickly transferred to an insulated container holding 100g of water at 22C. The temperature of the water rose to reach a final temperature of 35C. Which of the following is a valid conclusion? a) The metal temperature changed more than the water temperature did; therefore the metal lost more thermal energy than the water gained b) The metal temperature changed more than the water temperature did, but the metal lost the same amount of thermal energy as the water gained c) The metal temperature changed more than the water temperature did; therefore the heat capacity of the metal must be greater than the heat capacity of the water. d) The final temperature is less than the average starting temperature of the metal and the water; therefore the total energy of the metal and water decreased.

b) The metal temperature changed more than the water temperature did, but the metal lost the same amount of thermal energy as the water gained

Solid Al(NO3)3 is added to distilled water to produce a solution in which the concentration of nitrate, [NO3-], is .10M. What is the concentration of the aluminum ion, [Al3+], in this solution? a).010M b).033M c).066M d).10M e).30M

b).033M

Oxygen is being reduced in all of the following reactions except a) 2C(s) + O2(g) -> 2CO(g) b) S(s) + O2(g) -> SO2(g) c) 2F2(g) + O2(g) -> 2OF2(g) d) 2Na(s) + O2-> Na2O2(s) e) 2Mg(s) + O2(g) -> 2MgO(s)

c) 2F2(g) + O2(g) -> 2OF2(g)

Addition of sulfurous acid (a weak acid) to barium hydroxide (a strong base) results in the formation of a precipitate. Which of the following represents the net ionic equation for this reaction? a) 2H+(aq) + 2OH- -> 2H20(l) b) H2SO3(aq) + Ba2+(aq) + 2OH-(aq) -> BaSO3(s) + 2H2O(l) c) 2H+(aq) + SO3^2-(aq) + Ba2+(aq) +2OH-(aq) -> BaSO3(s) +2H20(l) d) H2SO3(aq) + Ba2+ + 2OH-(aq) -> Ba2+(aq) + SO3^2-(aq) +2H20(l) e) H2SO3(aq) + Ba(OH)2(aq) -> BaSO3(s) + 2H2O(l)

c) 2H+(aq) + SO3^2-(aq) + Ba2+(aq) +2OH-(aq) -> BaSO3(s) +2H20(l)

Under which of the following conditions of temperature and pressure will H2 gas be expected to behave most like an ideal gas? a) 50K and .10atm b) 50K and 5atm c) 500K and .10atm d) 500K and 50atm

c) 500K and .10atm

A hot iron ball is dropped into a 200.g sample of water initially at 50C. If 8.4 kJ of heat is transferred from the ball to the water, what is the final temperature of the water? a) 40C b) 51C c) 60C d) 70C

c) 60C

A 1 mol sample of Zinc can reduce the greatest number of moles of which of the following ions? a) Al3+ b) Pb2+ c) Ag+ d) Cl- e) N3-

c) Ag+

Complete combustion of a sample of a hydrocarbon in excess oxygen produces equimolar quantities of carbon dioxide and water. Which of the following could be the molecular formula of the compound? a) C2H2 b) C2H6 c) C4H8 d) C6H6

c) C4H8

The volume of a sample of air in a cylinder with a movable piston is 2.0 L at a pressure P1, as shown in the diagram above. The volume is increased to 5.0L as the temperature is held constant. The pressure of the air in the cylinder is now P2. What effect do the volume and pressure changes have on the average kinetic energy of the molecules in the sample? a) The average Kinetic energy increases b) The average Kinetic energy decreases c) The average Kinetic energy stays the same d) It cannot be determined how the kinetic energy is affected without known P2 and P2

c) The average Kinetic energy stays the same

The table above shows the first ionization energy and atomic radius of several elements. Which of the following best helps to explain the deviation of the first ionization energy of Oxygen from the overall trend? a) The atomic radius of oxygen is greater than the atomic radius of fluorine b) The atomic radius of oxygen is less than the atomic radius of nitrogen c) There is repulsion between paired electrons in oxygen's 2p orbitals d) There is attraction between paired electrons in oxygen's 2p orbitals

c) There is repulsion between paired electrons in oxygen's 2p orbitals

What is the molarity of I-(aq) in a solution that contains 34g of SrI2 (molar mass 341g) in 1.0 L of the solution? a) .034 M b) .068 M c) .10 M d) .20 M e) .68 M

d) .20 M

Beaker X and Beaker Y each contain 1.0 L of solution, as shown above. A student combines the solutions pouring them into a larger, previously empty beaker Z and observes the formation of a white precipitate. Assuming that volumes are additive, which of the following sets of solutions could be represented by the diagram above? a) 2.0 M AgNO3, 2.O M MgCl2, 4.0 M Mg(NO3)2 and AgCl(s) b) 2.0 M AgNO3, 2.0 M MgCl2, 2.0 M Mg(NO3)2 and AgCl(s) c) 2.0 M AgNO3, 1.0 M MgCl2, 1.0 M Mg(NO3)2 and AgCl(s) d) 2.0 M AgNO3, 1.0 M MgCl2, 1.o M Mg(NO3)2 and AgCl(s)

d) 2.0 M AgNO3, 1.0 M MgCl2, 1.o M Mg(NO3)2 and AgCl(s)

_C3H8(g) + _O2(g) -> _H2O(g) + _CO2(g) When the equation for the reaction represented above is balanced and all coefficients are reduced to the lowest whole number terms, the coefficient for O2(g) is? a) 1 b) 2 c) 3 d) 5 e) 6

d) 5

Which of the following correctly identifies which has the higher first-ionization energy, Cl or Ar, and supplies the best justification? a) Cl, because of its higher electronegativity b) Cl because of its higher electron affinity c) Ar, because of its completely filled valence shell d) Ar because of its higher effective nuclear charge

d) Ar because of its higher effective nuclear charge

Some pollutant gases in the atmosphere act as contributors to the formation of acid rain, a serious environmental problem. An example of such a gas is a) N2 b) O2 c) H2O d) NO2 e) CH4

d) NO2

When a student prepares an aqueous solution containing the five cations Ag+(aq), Hg2^2+(aq), Cu2+(aq), Mn2+(aq), and Ba2+(aq), the student observes that no precipitates form in the solution. Which of the following could be the identitiy of an anion in the solution? a) Cl-(aq) b) CO3^2-(aq) c) CrO4^2-(aq) d) NO3-(aq) e) SO4^2-(aq)

d) NO3_(aq)

The photoelectron spectra above shows the energy required to removed a 1s electron from a nitrogen atom and from an oxygen atom. Which of the following statements best accounts for the peak in the upper spectrum being to the right of the peak in the lower spectrum? a) Nitrogen atoms have a half filled p subshell b) There are more electron-electron repulsions in oxygen atoms than in nitrogen atoms c) Electrons in the p subshell of oxygen atoms provide more shielding than electrons in the p subshell of nitrogen atoms. d) Nitrogen atoms have a smaller nuclear charge than oxygen atoms

d) Nitrogen atoms have a smaller nuclear charge than oxygen atoms

To determine the percentage of water in a hydrated salt, a student heated a 1.2346g sample of the salt for 30 minutes; when cooled to room temperature, the sample weighed 1.1857g. After the sample was heated for an additional 10 minutes and again cooled to room temperature, the sample weighed 1.1632g. Which of the following should the student do next? a)use the smallest mass value to calculate the percentage of water in the hydrated salt b) Repeat the experiment with a new sample of the same mass and average the results c) Repeat the experiment with a new sample that has a different mass d) Reheat the sample until the mass is constant e) Use the average of the mass values obtained after the two heatings to calculate the percentage of water in the hydrated salt

d) Reheat the sample until the mass is constant

A sample of a compound contains 3.21 g of sulfur and 11.4 g of fluorine. Which of the following represents the empirical formula of the compound? a) SF2 b) SF3 c) SF4 d) SF5 e) SF6

e) SF6

When heated, metallic carbonates generally produce a) metallic peroxide +CO b) metal +CO + O2 c) metallic hydroxide + CO2 d) metallic oxalate +O2 e) metallic oxide +CO2

e) metallic oxide +CO2