Download Chemistry - Chap 12 Homework Answers 2014

Chemistry - Chap 12 Homework Answers 2014
1. State what the Kinetic-Molecular theory says about the particles of gases in terms of their:
a) size small (point masses= has mass but takes up no space)
b) motion rapid; random; travel in straight line, collisions are elastic
c) energy high energy
2. Compare the density and compressibility of gases versus liquids and solids.
solid, liquids = noncompressible. high density. gases = compressible and low density
3. Why is nearly seven times more energy needed to vaporize a given amount of water as to melt it? melting requires
overcoming some of the attractive forces because the particles can now slide over one another but are still in contact.
Boiling requires overcoming all attractive forces because the particles are freely moving
4. Briefly describe each of the following:
a) ionic bonds in ionic compounds- transfer of electrons making ions and att are electrostatic. strong bonds
b) covalent bonds in molecular compounds share localized prs of electrons. strong bonds
c) metallic bonds in metallic solids.- sea of electrons. mobile nondirectional. strong bonds
5. Describe the following:
a) dispersion forces attractions due to instantaneous dipoles. very weak
b) dipole-dipole forces- attractions due to permanent dipoles. weak
c) hydrogen bonds- att of H of one molecule to O,N,F of another. strongest of these
6. Identify the type of intermolecular forces acting in the liquid state of each of the following substances.
a. CH4 disp
b. HBr disp, dipole
c. NF3 disp, dipole
d. H2O disp, H
e. Cl2 dispersion
7. What is vapor pressure? On a microscopic basis, how does a vapor pressure develop in a closed flask containing a
small amount of liquid? What processes are going on in the flask?
pressure exerted by vapor above a liquid. High energy particles at surface escape and exert the pressure
8. Which substance in each pair would be expected to show the largest vapor pressure at a given temperature?
The largest vapor pressure means the particles are easy to separate, have low attractive forces:
a. H2O (l) or C4H10 (l) only disp while water has disp, dipole, and H bonding. butane’s molecules can separate much easier
b. C4H10 (l) or C8H18(l) both have only disp but octane is much larger. same reason as above
c. HCl (l) or H2O (l) HCl has disp and dipole but water has all 3. same reasons.
d.. Br2 or PH3 bromine has disp whiles PH3 is disp, and dipole so same reason
e. H2O or NH3 both have disp, and H bonding. Water can H bond 4 times and 2 l.p. where ammonia has only 1 l.p.
For 9-21, choose one of the following terms to match the definition or description given.
9 f 10 I 11 a 12 e 13 h 14 c 15 m 16 g 17 b 18 k 19 20 d 21 j
22. Which of the substances in each of the following sets would be expected to have the highest melting point? Explain
why.
a. H2, N2, Br2 all disp but bromine largest so most attractions
b. H2O, NaCl, He sodium chloride ionic other two are molecular. ionic much higher m.p (memory)
c. H2, HCl, H2O hydrogen disp only, HCl disp, and dipole but water all 3.
23.. Classify each of the following solids and describe their properties.
a. CaSO4 ionic (has a polyatomic ION). high mp/bp, insulator as solid but conductor as liquid, brittle, low vp
b. diamond network. (memory) very high mp.bp, insulator, brittle, very low vp
c. Zn metallic.(duh!) high mp/bp, malleable, ductile, conductor, luster, low vp
d. glucose, C6H12O6 molecular. low mp/bp, insulator, soft, higher vp
e. Xe atomic (but same category as molecular) low mp/bp, insulator, soft, higher vp
Chemistry - Chap 12 Homework II Answers
1. Complete the following table.
Phase at room temperature = solid, liquid, or gas. Physical properties = brittle, malleable, gas, etc.
Compound
Type
Forces present
Phase
at r.t.
Name
Hydrogen
Ammonia
High
or low
mp/bp
low
Low
H2
1-NH3
molecular
molecular
Gas
Gas
H2O
molecular
CH3CH2-OH
molecular
2-SO2
CO2
3-CaCO3
molecular
molecular
Ionic
dispersion
Dispersion,
H bonding
Dispersion,
H bonding
Dispersion,
H bonding
dispersion
dispersion
Ionic bonds
LiClO3
ionic
4-PH3
molecular
He
CH4
Al(NO3)3
Physical properties at
r.t.
Soft,insulator
Soft,insulator
Liquid
Water
Low
Soft,insulator
liquid
Ethyl alcohol
Low
Soft,insulator
gas
gas
Solid
Sulfur dioxide
Carbon dioxide
Calcium carbonate
Low
Low
high
Ionic bonds
solid
Lithium chlorate
High
Gas
Gas
Gas
Solid
Phosphorous
trihydride
Helium
Methane
Aluminum nitrate
Low
element
molecular
ionic
Dispersion,
dipole-dipole
Dispersion
Dispersion
Ionic bonds
Soft,insulator
Soft,insulator
Brittle, insulator as
solid but cond as
liquid
Brittle, insulator as
solid but cond as
liquid
Soft,insulator
Low
Low
High
C4H10
molecular
Dispersion
Gas
Butane
Low
Soft,insulator
Soft,insulator
Brittle, insulator as
solid but cond as
liquid
Soft,insulator
C
Covalent bonds
Solid
Diamond
High
Hard, brittle, insulator
5-Fe
Network
covalent
metallic
Metallic bond
Solid
Iron
High
Mg
metallic
Metallic bond
Solid
Magnesium
High
CCl4
molecular
dispersion
Gas
Low
C12H22O11
molecular
Dispersion,
H Bonding
Solid
Carbon
tetrachloride
Sucrose
Maleable, ductile,
cond, luster
Maleable, ductile,
cond, luster
Soft,insulator
Low
Soft,insulator
2. Rank items numbered 1,2,3,4 and 5 above from lowest to highest in terms of their
a) boiling point/melting point 1,2,4,3 and 5 tie
(1,2,4= disp and dip.)
(2 larger than 1 & 3 (but barely))
4 & 5 = high
b) vapor pressure. Reverse a answers (remember high attract = high m.p and low v.p)
3. Explain the following data.
Compound
CH4 only london (dispersion) so low
B. P. (oC)
-161
Cmpd
HBr london and dipole so larger than just
B.P.
-70
london
C2H6 london but larger so higher than above
C3H8 london and larger that other two above
F2 london and really small
Br2 london and big and magic
-89
-30
-188
59
HI same as HBr but larger
-37
Rank the compounds above from 1-7 for vapor pressure, with 1 being the lowest vapor pressure and 7 the
highest. Reverse the b.p.order (same as earlier)
4. Rank the following compounds from lowest to highest for their boiling points:
KBr= 4 (highest) H2 =1 (lowest)
C6H12O6 = 3
ionic, (rule )
molec; disp only
molec; disp, dipole, H bond
SO3= 2
molec; disp, dipole
5. Know the definitions for the following terms:
ionic solid
covalent network solid
molecular solid
Look them up, lazy
intermolecular
dipole-dipole
attraction
dispersion forces
cohesion and adhesion
viscosity
surface tension
fluidity
boiling point
vapor pressure
vaporization
6. Naming Practice
Magnesium hydroxide
ammonium sulfide
trisulfur nonoxide
sulfur hexafluoride
H2SO4
HC2H3O2
HNO3
SnCO3
Cu3(PO4)2
Al2(SO4)3
Fe(C2H3O2)3
Pb(SO3)2
Multiple Choice Ans
1. A
2. C
7. A
8. D
13. B
14. C
Mg(OH)2
(NH4)2S
S3O9
SF6
sulfuric acid
acetic acid
nitric acid
Tin(II) carbonate
Copper(II) phosphate
Aluminum sulfate
Iron(III)acetate
Lead(II) sulfite
3. B
9. A
15. B
4. A
10. A
16. D
5. C
11. D
6. D
12. D