Solutions Manual for CHEM 2 Chemistry in Your World
2nd Edition by Hogg
ISBN 113396298X 9781133962984
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1. Definitions
a. A cation is an ion with a positive charge.
b. An anion is an ion with a negative charge.
c. Atoms react to acquire an electron configuration with 8 electrons in the outermost shell to match the configuration of the nearest noble gas.
d. The formula unit is the simplest element ratio for an ionic compound like NaCl instead of Na2Cl2.
2. Definitions
a. Nonmetals are elements that form negative ions and acidic oxides, are nonconductors of heat and electricity. They are found in the upper right corner of the Periodic Table.
b. A compound consisting of two different elements like carbon monoxide, CO
3. Definitions
a. a pair of electrons shared between two atoms
b. four electrons (2 pairs) shared by two atoms
c. six electrons (3 pairs) shared between two atoms
d. pair of valence electrons on an atom that are not shared with another atom
e. a pair of electrons shared between two atoms
f. either a double or a triple bond
4. Definitions
a. A covalent bond exists between two atoms that share two or more electrons
b. An ion consisting of two or more different elements, like PO4 3
c. The type of bond that exists between two oppositely charged ions like Na+ and Cl .
d. a compound formed between two elements
5. Definitions
a. bond between two atoms that share electrons equally
b. bond between two atoms that do not attract shared electrons equally
6. The octet rule says that atoms lose and gain electrons to reach the nearest noble gas electron configuration. Sodium, 2-8-1, would lose one electron to achieve the 10 electron neon noble gas electron configuration, 2-8. A nonmetal like oxygen, 2-6, would gain two electrons to achieve the 2-8 electron configuration of neon.
7. Definition/description
a. A hydrocarbon is a compound consisting only of carbon and hydrogen.
b. a compound consisting only of carbon and hydrogen with only single bonds
c. a compound consisting only of carbon and hydrogen with one or more multiple bonds between carbon atoms
d. Alkenes are hydrocarbons with one or more carbon-carbon double bonds.
8. A Ca3+ ion is not possible because the energy required to remove a third electron is much greater than the energy available in chemical reactions. This third electron would need to come from the set of electrons in the noble gas 2-8-8 electron configuration for argon.
9. Predict the ions
a. Br1
b. Al3+
c. Nal+
d. Ba2+
e. Ca2+
f. Ga3+
g. I1
h. S2-
i. Group 1A atoms lose one valence electron to form a +1 ion, see 9c above.
j. Group 7A atoms have seven valence electrons and gain one to form a 1- ion, see 9g.
10. An ion with 12 protons and 10 electrons will have a +2 charge; magnesium has 12 protons, Mg2+ The number of protons stays the same. The number of protons exceeds the number of electrons by 2.
11. Formulas and names
a. AlI3 aluminum iodide
b. SrCl2 strontium chloride
c. Ca3N2 calcium nitride
d. K2S potassium sulfide
e. Al2S3 aluminum sulfide
f. Li3N lithium nitride
12. Electrostatic attractions between positive and negative ions in an ionic lattice hold the solid
together. These attractions are not limited to the nearest ions. The example is a NaCl lattice. Each ion is attracted to all the oppositely charged ions in the lattice. The attraction decreases as the distance between oppositely charged ions increases.
13. Nomenclature
a. calcium sulfate
b. sodium phosphate
c. sodium bicarbonate
d. potassium hydrogen phosphate
e. sodium nitrite
f. copper(II) nitrate
14. Variants
a. water or dihydrogen monoxide
b. molecular oxygen or dioxide
c. hydrogen peroxide or dihydrogen dioxide
15. Formulas
a. Lithium is in Group 1A so it forms the Li1+ ion. Tellurium is in Group 6A and forms the Te2 ion. The formula for the neutral ionic combination is Li2Te.
b. MgBr2
c. Ga2S3
16.
b. SrCO3
c. Mg(OH)2
d. Fe2O3
e. K2PO4
17. a. With a ratio of three telluride anions for every two bismuth cations, the most likely formula is Bi2Te3
b. Bismuth cations have a +3 charge, so for bismuth telluride to be electrically neutral, the telluride anion must have a charge of –2.
18. Because the ammonium cation has a charge of +1, the charge of the perchlorate anion must be –1 for the compound to be electrically neutral.
19.
a. (NH4)3PO4
b. Na2SO4
c. CuCl2
d. Cr(NO3)3
e. KBr
f. CaCO3
g. NaClO
20. Ionic bonds differ from covalent because of the differences in the kinds of atoms that are bonded. Ionic bonds are formed between atoms of widely different electron attracting power; the more electron attracting atom gains one or more electrons to become a negative ion and the less electron attracting atom loses one or more electrons to become a positive ion. Covalent bonds are formed between atoms of similar electron attracting power; the two atoms share one or more pairs of electrons to give complete octets; neither atom gains or loses a whole electron. Metals typically combine with nonmetals to form ionic bonds while nonmetals and nonmetals combine to form covalent bonds.
21. Types of bonding
a. ionic
b. covalent
c. ionic
d. covalent
e. covalent
22. Inorganic compounds
23. Formulas and names
a. NO, nitrogen monoxide
b. SO3, sulfur trioxide
c. N2O, dinitrogen oxide
d. NO2, nitrogen dioxide
24.
a. Covalent, nitrogen tribromide
b. Ionic, zinc iodide
c. Covalent, carbon tetrachloride
d. Covalent, hydrogen bromide
e. Ionic, chromium(III) oxide
e. f. g. h.
26. Ionic bonding exists between oppositely-charged ions. The polar covalent bond exists between atoms that share electrons unequally. The nonpolar bonding exists between atoms that share electrons equally (atoms with similar attractions for electrons).
27. Shapes
a. Tetrahedral b. Trigonal-pyamidal c. Bent
28. Polarity
a. The electron attracting power differences determine the polarity of the bonds. The farther apart two elements are in the periodic table the more polar the bond. The C Cl bond is more polar because they are farther apart in the periodic table.
b. The C F bond is more polar than the C Cl bond.
29. The octet rule states that in order for an atom to be stable it must have a total of 8 electrons or 4 pairs (either lone or bonding pairs) around it. A molecule with an odd number of electrons will have one electron that is not paired and not satisfy the octet rule. For example, NO has 11 valence electrons with only oxygen satisfying the octet rule with 8 valence electrons while nitrogen only has 7 electrons and will never satisfy the octet rule unless nitrogen gains an electron.
30. eleven valence electrons
31. H F because the difference in electronegativity is the greatest. Fluorine draws electrons away from hydrogen more than chlorine and bromine because it has the highest electronegativity.
32. Polarity of molecules
a. Polar; O is the negative end and C is the positive end. The arrow indicates the direction electrons shift in the molecule.
b. Nonpolar; the bonds are nonpolar. The molecule is tetrahedral and symmetric.
c. Nonpolar; the bonds are polar but the planar triangular shape puts the center of positive charge and the center of negative charge in the middle of the boron atom.
d. Polar; F is the negative end and H is the positive end.
33. Polarity of molecules
a. Polar; oxygen draws electrons and makes that end of the molecule negative.
b. Nonpolar; there are no polar bonds in the butane molecule.
c. Polar; nitrogen draws electrons so the nitrogen end of the molecule is negative; the molecule is a trigonal pyramid.
34. States of Matter
a. The gaseous state has no definite shape or volume; a gas takes the shape and volume of its container. Gases are compressible.
b. A liquid has definite volume and assumes the shape of the container. The liquid molecules are free to move past each other, allowing the liquid to flow and assume the shape of its container. Liquids are relatively incompressible.
c. The solid state has definite shape and definite volume. The molecules or ions making up the solid are in direct contact and located at fixed positions. The solid is incompressible due to direct contact between the particles.
35. Pairs in ethanol
a. The total valence electron count is done by adding all contributions from each atom.
b. 8 single bonds
c. 8 bonding pairs
There are 2 nonbonding pairs of electrons on the oxygen (see figure below)
36. a electron geometry = tetrahedral; molecular geometry = tetrahedral
b. electron geometry = tetrahedral; molecular geometry = trigonal pyramidal
37. (b) solid
38. A gas has the greatest average distance between particles. Gas compressibility is evidence for this.
39. The number of gas molecules in a given volume of gas decreases as you move away from the earth's surface. The fewer number of molecules collide with any object less often and exert less push or pressure. Additionally, the force of Earth's gravity decreases with altitude. This results in less weight or force per unit area at greater altitudes.
40. Particles in a liquid are in constant motion; this is shown when one liquid diffuses in another (a drop of ink or food coloring will slowly spread throughout a glass of water even though you do not stir the mixture). Particles in a liquid are close together. This makes liquids nearly incompressible.
41. Gas molecules are constantly moving. The gas molecules of the perfume vapor diffuse away from the person wearing the perfume.
42. Pressure in an automobile tire decreases in cold weather because average kinetic energy goes down and molecules collide less often with the tire walls. The tire volume remains the same at all temperatures.
43. Water has an unusually high normal boiling point and surface tension. Additionally it expands on freezing.
44. H bonding
Hydrogenbonds
The hydrogen bond (shown as a faint line) in water exists between a hydrogen atom in one water molecule and an oxygen atom in a different water molecule. One oxygen atom is typically hydrogen bonded to two different water molecules.
45. Evaporation of water from one's skin draws energy from the skin. This produces a resulting "chilling" sensation. We are cooled when the energy flows into the evaporating liquid.
46. Structure and Hydrogen bonding
a. Yes. Hydrogen is covalently bonded to a very electron attracting oxygen atom. The hydrogen in the O-H group can hydrogen bond to an oxygen in another molecule.
b. Yes. In ammonia, hydrogen is covalently bonded to a very attracting nitrogen atom. The N-H bond is very polar and hydrogens in one NH3 can hydrogen bond to a nitrogen in a different NH3 molecule.
c. No. Sulfur dioxide, SO2, has no hydrogens so no hydrogen bonding is possible even though it is a bent polar molecule.
d. No. Carbon dioxide, CO2, has no hydrogens so it cannot show hydrogen bonding. It is a linear nonpolar molecule.
e. No. Methane does not show hydrogen bonding even though it has four hydrogens. The electron attracting power of hydrogen and carbon are similar. The CH bond is not polar enough to produce hydrogen bonding between methane molecules.
f. Yes. Hydrogen is covalently bonded to fluorine in HF. The electron attracting powers are very different. This is the most polar bond formed by a hydrogen atom. The hydrogen in one HF molecule can hydrogen bond to fluorines in neighboring HF molecules.
g. No. The hydrogens are bonded to the carbon atoms not the oxygen. The electron attracting power of carbon and hydrogen are similar so the bonds are not polar enough to produce hydrogen bonding.
47. The solubility of an ionic substance is dependent on the strength of the attraction between the ions and the strength with which the solvent (water, here) can hold on to dissolved ions. The insolubility must be a result of an attraction between barium and sulfate ions that is stronger than the attraction between water and barium or sulfate ions.
48. Without hydrogen bonding the boiling point for ammonia would be 100°C. See Figure 5.9.
49. There are great distances between particles in the gas state while particles in the liquid and solid states are in direct contact. The gas molecules are separated by distances equal to about 1000 molecular diameters. This is empty space, a vacuum.
50. Because heat is being released, the process is exothermic.
51. The increased pressure creates more collisions of gas molecules with the solvent surface. These more frequent collisions create more opportunities for the gas to dissolve in the solvent. Champagne, sparkling waters, Coca-Cola, and Pepsi are examples.
52. Attractive forces between particles in the surface layer are unbalanced because the particles are attracted by the bulk of the liquid below the surface. Water has a high surface tension because of the strong intermolecular forces between molecules.
53. The concentration of dissolved oxygen is controlled by the relation C = kP. The concentration of dissolved oxygen is 0.0109 g O2/L when the pressure is 1 atm. This means that when the O2 pressure decreases from 1 atm to 0.5 atm the concentration of oxygen will decrease by ½ to 0.00545 g/L. Rounded to 1 sf this becomes 0.005 g/L.
54. three times as much
55. solid because temperature is lower than mp
56. When acetone is at 50°C and 1 atm, this is warmer than the melting point of 95°C and colder than the normal boiling point of boils at 56.5°C. Acetone will be a liquid.
57. below 646°C, at approximately 500°C.
58. Octane, C8H18, should have a boiling point between the boiling points for heptane, C7H16; 98.4°C and nonane, C9H20; 150°C. The boiling points can be assumed to increase by a regular amount with every additional CH2 unit. The boiling point increased by 29.7°C when the molecule size increased from hexane to heptane. From heptane to nonane the boiling point change is 52.4°C. The boiling point for octane should be about halfway between the heptane and nonane boiling points. This would make it about 26-30°C more than 98.4°C. A boiling point in the range of 124-128°C for octane is a reasonable answer.
