Review Sheet Ch 10, 6, 7 and Equations

Name______AP Chem

Review Sheet Ch 10, 6, 7 and Equations

(A) CO32¯
(B) Cr2O72¯
(C) NH4+
(D) Ba2+
(E) Al3+

Assume that you have an "unknown" consisting of an aqueous solution of a salt that contains one of the ions listed above. Which ions must be absent on the basis of each of the following observations of the "unknown"?

1. The solution is colorless B
2. The solution gives no apparent reaction with dilute hydrochloric acid. A
3. No odor can be detected when a sample of the solution is added drop by drop to a warm solution of sodium hydroxide. C
4. No precipitate is formed when a dilute solution of H2SO4 is added to a sample of the solution. D

5. Which of the following represents a pair of isotopes? D

Atomic
Number / Mass
Number
(A) / I.
II. / 6
7 / 14
14
(B) / I.
II. / 6
14 / 7
14
(C) / I.
II. / 6
14 / 14
28
(D) / I.
II. / 7
7 / 13
14
(E) / I.
II. / 8
16 / 16
20

6. ____Mg(s) + ___NO3¯(aq) +___H+(aq) ___Mg2+(aq) + ___NH4+(aq) + ___H2O(l)

When the skeleton equation above is balanced and all coefficients reduced to their lowest whole-number terms. what is the coeficient for H+ ? E

(A) 4(B) 6(C) 8(D) 9(E) 10

1. When a sample of oxygen gas in a closed container of constant volume is heated until its absolute temperature is doubled, which of the following is also doubled? B

(A) The density of the gas
(B) The pressure of the gas
(C) The average velocity of the gas molecules
(D) The number of molecules per cm3
(E) The potential energy of the molecules

1. 1s2 2s22p6 3s23p3

Atoms of an element, X, have the electronic configuration shown above. The compound most likely formed with magnesium, Mg, is E

(A) MgX
(B) Mg2X
(C) MgX2
(D) MgX3
(E) Mg3X2

1. The density of an unknown gas is 2.00 grams per liter at 3.00 atmospheres pressure and 127 °C. What is the molecular weight of this gas? (R = 0.0821 liter-atm / mole-K) C

(A) 254/3 R
(B) 188 R
(C) 800/3 R
(D) 600 R
(E) 800 R

1. The formula for potassium hexacyanoferrate(II) is A

(A) K4[Fe(CN)6]
(B) K3[Fe(CN)6]
(C) K2[Pt(CN)4]
(D) K2[Pt(CN)6]
(E) KCN

1. The net ionic equation for the reaction between silver carbonate and hydrochloric acid is A

(A) Ag2CO3(s) + 2 H+ + 2 Cl¯  2 AgCl(s) + H2O + CO2(g)
(B) 2 Ag+ + CO32¯ + 2 H+ + 2 Cl¯  2 AgCl(s) + H2O + CO2(g)
(C) CO32¯ + 2 H+ H2O + CO2(g)
(D) Ag+ + Cl¯  AgCl(s)
(E) Ag2CO3(s) + 2 H+ 2Ag+ + H2CO3

1. ___CrO2¯ + ___OH¯  ___CrO42¯ + ___H2O + ___ e¯

When the equation for the half-reaction above is balanced, what is the ratio of the coefficients OH¯ / CrO2¯ ? D

(A) 1:1(B) 2:1 (C) 3:1(D) 4:1 (E) 5:1

1. Equal masses of three different ideal gases, X, Y, and Z, are mixed in a sealed rigidcontainer. If the temperature of the system remains constant, which of the following statements about the partial pressure of gas X is correct? C

(A) It is equal to 1/3 the total pressure
(B) It depends on the intermolecular forces of attraction between molecules of X, Y, and Z.
(C) It depends on the relative molecular masses of X, Y, and Z.
(D) It depends on the average distance traveled between molecular collisions.
(E) It can be calculated with knowledge only of the volume of the container.

1. The molality of the glucose in a 1.0-molar glucose solution can be obtained by using which of the following?E

(A) Volume of the solution
(B) Temperature of the solution
(C) Solubility of glucose in water
(D) Degree of dissociation of glucose
(E) Density of the solution

1. Metallic copper is heated strongly with concentrated sulfuric acid. The products of this reaction are B

(A) CuSO4(s) and H2(g) only
(B) Cu2+, SO2(g), and H2O
(C) Cu2+, H2(g), and H2O
(D) CuSO4(s), H2(g), and SO2(g)
(E) Cu2+, SO3(g), and H2O

1. The elements in which of the following have most nearly the same atomic radius? E

(A) Be, B, C, N
(B) Ne, Ar, Kr, Xe
(C) Mg, Ca, Sr, Ba
(D) C, P, Se, I
(E) Cr, Mn, Fe, Co

1. What number of moles of O2 is needed to produce 142 grams of P4O10 from P? (Molecular weight P4O10 = 284) D

(A) 0.500 mole
(B) 0.625 mole
(C) 1.25 mole
(D) 2.50 mole
(E) 5.00 mole

1. The alkenes are compounds of carbon and hydrogen with the general formula CnH2n. If 3.50 gram of any alkene is burned in excess oxygen, what number of moles of H2O is formed? A

(A) 0.250 mole
(B)0.375 mole
(C) 0.500 mole
(D) 2.50 mole
(E) 5.00 mole

1. When the actual gas volume is greater then the volume predicted by the ideal gas law, the explanation lies in the fact that the ideal gas law does NOT include a factor for molecular ______.A

(A) volume(B) mass(C) velocity(D) attractions(E) shape

1. 5 Fe2+ + MnO4¯ + 8 H+ 5 Fe3+ + Mn2+ + 4 H2O

In a titration experiment based on the equation above, 100.0 milliliters of an acidified Fe2+ solution requires 14.0 milliliters of standard 0.050-molar MnO4¯ solution to reach the equivalence point. The concentration of Fe2+ in the original solution is C

(A) 0.0035 M
(B) 0.0070 M
(C) 0.035 M
(D) 0.070 M
(E) 0.14 M

1. A 20.0-milliliter sample of 0.200-molar K2CO3 solution is added to 30.0 milliliters of 0.400-molar Ba(NO3)2 solution. Barium carbonate precipitates. The concentration of barium ion, Ba2+, in solution after reaction is B

(A) 0.150 M
(B) 0.160 M
(C) 0.200 M
(D) 0.240 M
(E) 0.267 M

1. One of the outermost electrons in a rubidium atom in the ground state can be described by which of the following sets of four quantum numbers? E

(A) 5, 2, 0, 1/2
(B) 5, 1, 1, 1/2
(C) 5, 1, 0, 1/2
(D) 5, 0, 1, 1/2
(E) 5, 0, 0, 1/2

2004 D

Answer the following questions about carbon monoxide, CO(g), and carbon dioxide, CO2(g). Assume that both gases exhibit ideal behavior.

(a)Draw the complete Lewis structure (electron dot diagram) for the CO molecule and for the CO2 molecule.

(b)Identify the shape of the CO2 molecule. (HAVE NOT COVERED THIS YEAR)

(c)One of the two gases dissolves readily in water to form a solution with a pH below 7. Identify the gas and account for this observation by writing a chemical equation.

(d)A 1.0 mol sample of CO(g) is heated at constant pressure. On the graph below, sketch the expected plot of volume verses temperature as the gas is heated.

(e)Samples of CO(g) and CO2(g) are placed in 1 L containers at the conditions in the diagram below.

(i)Indicate whether the average kinetic energy of the CO2 is greater than, equal to, or less than the average kinetic energy of the CO(g) molecules. Justify your answer.

(ii)Indicate whether the root-mean-square speed of the CO2(g) molecules is greater than, equal to or less than the root-mean-square speed of the CO(g) molecules. Justify your answer.

(iii)Indicate whether the number of CO2(g) molecules is greater than, equal, or less than the number of CO(g) molecules. Justify your answer.

Answer:

(a)

(b)linear

(c)CO2; CO2 + H2O  H+ + HCO3–

(d)

(e)(i) equal to; at the same temperature, all gas molecules have the same kinetic energy

(ii)less, since CO2 has a molar mass of 44 and CO has a mass of 28, the lighter molecule is faster at the same temperature

(iii) less; Avogadro’s Hypothesis, equal volumes of gas at the same temperature and pressure contain equal number of molecules. Since the pressure of CO2 is half the pressure of the CO, it must contain half as many molecules.

2003 B

A rigid 5.00 L cylinder contains 24.5 g of N2(g) and 28.0 g of O2(g)

(a)Calculate the total pressure, in atm, of the gas mixture in the cylinder at 298 K.

(b)The temperature of the gas mixture in the cylinder is decreased to 280 K. Calculate each of the following.

(i)The mole fraction of N2(g) in the cylinder.

(ii)The partial pressure, in atm, of N2(g) in the cylinder.

(c)If the cylinder develops a pinhole-sized leak and some of the gaseous mixture escapes, would the ratio in the cylinder increase, decrease, or remain the same? Justify your answer.

A different rigid 5.00 L cylinder contains 0.176 mol of NO(g) at 298 K. A 0.176 mol sample of O2(g) is added to the cylinder, where a reaction occurs to produce NO2(g).

(d)Write the balanced equation for the reaction.

(e)Calculate the total pressure, in atm, in the cylinder at 298 K after the reaction is complete.

Answer:

(a)24.5 g N2 = 0.875 mol N2

28.0 g O2 = 0.875 mol O2

P = =

= 8.56 atm

(b)(i) = 0.500 mole fraction N2

(ii)

= 8.05 atm  mole fraction = 8.05 atm  0.500

= 4.02 atm N2

(c)decrease; since N2 molecules are lighter than O2 they have a higher velocity and will escape more frequently (Graham’s Law), decreasing the amount of N2 relative to O2

(d)2 NO + O2 2 NO2

(e)all 0.176 mol of NO will react to produce 0.176 mol of NO2, only 1/2 of that amount of O2 will react, leaving 0.088 mol of O2, therefore, 0.176 + 0.088 = 0.264 mol of gas is in the container.

P = =

= 1.29 atm

1993 D

Account for each of the following in terms of principles of atom structure, including the number, properties, and arrangements of subatomic particles.

(a)The second ionization energy of sodium is about three times greater than the second ionization energy of magnesium.

(b)The difference between the atomic radii of Na and K is relatively large compared to the difference between the atomic radii of Rb and Cs.

(c)A sample of nickel chloride is attracted into a magnetic field, whereas a sample of solid zinc chloride is not.

(d)Phosphorus forms the fluorides PF3 and PF5, whereas nitrogen forms only NF3.

ANSWER

(a)Electron configurations:

Na: 1s2 2s22p6 3s1Mg: 1s2 2s22p6 3s2

One of the following explanations:

Octet/noble gas stability comparison

Energy difference explanation

Size difference explanation

and shielding/effective nuclear charge discussion.

(b)Correct direction and explanation of any one of the following: (1) shielding differences; (2) energy differences; (3) #proton/#electron differences

(c)Any one of the following:

(1) Ni unpaired electrons / paramagnetic; (2) Zn paired electrons / diamagnetic; (3) Ni unpaired electrons / Zn paired electrons; (4) Ni paramagnetic / Zn diamagnetic.

and orbital discussions / Hund’s Rule / Diagrams.

(d)Expanded octet or sp3d hybrid of phosphorous and lack of d orbitals in nitrogen. or

Nitrogen is too small to accommodate (bond) 5 fluorines or 5 bonding sites.

2006 D

Suppose that a stable element with atomic number 119, symbol Q, has been discovered.

(a)Write the ground-state electron configuration for Q, showing only the valence-shell electrons.

(b)Would Q be a metal or a nonmetal? Explain in terms of electron configuration.

(c)On the basis of periodic trends, would Q have the largest atomic radius in its group or would it have the smallest? Explain in terms of electronic structure.

(d)What would be the most likely charge of the Q ion in stable ionic compounds?

(e)Write a balanced equation that would represent the reaction of Q with water.

(f)Assume that Q reacts to form a carbonate compound.

(i)Write the formula for the compound formed between Q and the carbonate ion, CO32–.

(ii)Predict whether or not the compound would be soluble in water. Explain your reasoning.

ANSWER

(a)8 s1

(b)metal. It has one valence electron that it easily looses, consistent with the other alkali metals in its family.

(c)Q would have the largest atomic radius in its group. Every time another s-orbital is added to an element, it creates a bigger electronic shell.

(d)+1

(e)2 Q + 2 H2O  2 Q+ + H2 + 2 OH–

(f)(i) Q2CO3

(ii) soluble in water. With very few exceptions, all alkali metal salts are soluble in water.

For each of the following three reactions, in part (i) write a balanced equation for the reaction and in part (ii) answer the question about the reaction. In part (i), coefficients should be in terms of lowest whole numbers. Assume that solutions are aqueous unless otherwise indicated. Represent substances in solutions as ions if the substances are extensively ionized. Omit formulas for any ions or molecules that are unchanged by the reaction. You may use the empty space at the bottom of the next page for scratch work, but only equations that are written in the answer boxes provided will be graded.

(a)Aqueous sodium hydroxide is added to a saturated solution of aluminum hydroxide, forming a complex ion.

(i)Balanced equation:

(ii)If the resulting mixture is acidified, would the concentration of the complex ion increase, decrease, or remain the same? Explain.

(b)Hydrogen chloride gas is oxidized by oxygen gas.

(i)Balanced equation:

(ii)If three moles of hydrogen chloride gas and three moles of oxygen gas react as completely as possible, which reactant, if any, is present in excess? Justify your answer.

(c)A small piece of sodium is placed in a beaker of distilled water.

(i)Balanced equation:

(ii)The reaction is exothermic, and sometimes small flames are observed as the sodium reacts with the water. Identify the product of the reaction that burns to produce the flames.

Answer:

(a)(i)Al(OH)3 + OH-[Al(OH)4]-

(ii) decrease; H+ will neutralize OH- and destroy the complex

(b)(i)2 HCl + O2H2O + OCl2or 4 HCl + O2 2 H2O + 2 Cl2

(ii)O2 in excess; reacting on a 2:1 mole ratio, 3 mol HCl requires only 1.5 mol of O2

(c)(i)Na + H2O Na+ + OH– + H2

(ii) hydrogen gas