Chapter 1 Basic Concepts of Chemistry
I NSTRUCTOR
’
S N OTES
This chapter discusses a wide range of basic subjects needed for the study of chemistry. How you use the material will depend on the preparation level of your students. Essentially all of the topics in this chapter would be found in a typical high school chemistry class. However, if students took that course two or three years earlier, or if their performance at that time was inconsistent with their present goal of a professional study for science or engineering, an extensive review might be necessary. Such a review could take two or three lecture periods. If your class consists of students who have been screened by a placement exam or other process to reasonably ensure that they have good abilities in high school chemistry, you may assign most or even all of the chapter for outside reading with only a single class to review and stress key points. The chapter can stand on its own without direct instruction if your students learned the topics previously. For an intermediate approach you could assign sections 1.1-1.4 for student reading then take one lecture for the rest of the chapter.
A pre-quiz selected from Chapter 1 Study Questions could help establish what degree of review is needed for your students.
S UGGESTED D EMONSTRATIONS
1. Density
 Kolb, K. E.; Kolb, D. K. “Method for Separating or Identifying Plastics,”
Journal of Chemical Education
1991 , 68 , 348.
 Franz, D. A. “Densities and Miscibilities of Liquids and Liquid Mixtures,”
Journal of Chemical Education
1991 , 68 , 594.
 Checkai, G.; Whitsett, J. “Density Demonstration Using Diet Soft Drinks,”
Journal of Chemical Education
1986 , 63 , 515.
 Shakhashiri, B. Z. “Density and Miscibility of Liquids,”
Chemical Demonstrations: A Handbook for
Teachers of Chemistry; University of Wisconsin Press, 1989; Vol. 3, pp. 229–233.
2. Properties of Elements

Pictures of the elements and their uses can be found on the Periodic Table Videodisc and on the Periodic
Table Live! CD-ROM available from JCE Software.
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Chapter 1 Basic Concepts of Chemistry
3. Illustration of “Physical Change”

Liquid nitrogen is always a favorite of students. We freeze a banana, a hot dog, a flower, or similar object.
4. Illustration of “Chemical Change”
 The first lecture in the course is often begun with a “bang” by setting off several hydrogen-filled balloons in a darkened lecture room. The demonstration is described in Chemical Demonstrations: A Handbook for
Teachers of Chemistry; University of Wisconsin Press, 1983; Vol. 1, pp. 106–112. The reaction is also shown on the General ChemistryNow CD-ROM , the Periodic Table Videodisc and the Periodic Table Live!
CD-ROM.

Other reactions could be done as well, depending on the facilities available. Possibilities include placing small pieces of potassium in water, the thermite reaction (Shakhashiri, Volume 1, page 85), or the reaction of zinc and ammonium nitrate (Shakhashiri, Volume 1, page 51). The latter reaction gives off a large amount of ZnO dust and other irritating fumes. It is not suitable for a room without good ventilation.

For fun, and to give some color, as well as talking about our future study of acid-base reactions, we add aqueous NH
3
to separate flasks containing (i) very dilute acid with phenolphthalein, (ii) Al(NO
3
)
3
, and (iii) dilute CuSO
4
.

We often have a student contribute a penny to put into concentrated HNO
3
. The reaction brings up a brief discussion of oxidation–reduction processes. The NO
2
gas generated prompts a discussion of air pollution problems, as well as the fuels used in the Lunar Lander and in the Space Shuttle. (CAUTION: NO
2
is a very corrosive gas. Use only in a well ventilated room. We do the reaction by putting the penny in a few milliliters of acid in a 2-L Erlenmeyer flask that is lightly stoppered. This effectively contains the gas.)

The Periodic Table Videodisc and the Periodic Table Live! CD-ROM can be used to explore reactions of the elements with air, water, acids, and bases. Examples include the reaction of potassium with water and the reaction of cobalt with HCl and HNO
3
.
2

Chapter 1 Basic Concepts of Chemistry
S OLUTIONS TO S TUDY Q UESTIONS
1.1
1.2
1.3
1.4
1.5
1.6
(a) C
(b) K
Carbon
Potassium
(c) Cl
(d) P
(a) Mn
(b) Cu
(a) barium
(b) titanium
(c) chromium
Manganese (c) Na
Copper (d) Br
Ba
Ti
Cr
(a) silver
(b) aluminum
(c) plutonium
Ag
Al
Pu
Chlorine
Phosphorus
Sodium
Bromine
(d) lead
(e) arsenic
(f) zinc
(d) tin
(e) technetium
(f) krypton
(a) NaCl is a compound; sodium is an element
(b) Sugar is a compound; carbon is an element.
(c) Gold chloride is a compound; gold is an element.
(a) Pt(NH
3
)
2
Cl
2
is a compound; Pt is an element
(b) Copper is an element; copper(II) oxide is a compound
(c) Silicon is an element; sand is a compound
(e) Mg
(f) Ni
(e) Xe
(f) Fe
Pb
As
Zn
Sn
Tc
Kr
Magnesium
Nickel
Xenon
Iron
1.7
1.8
(a) physical property
(b) chemical property
(c) chemical property
(d) physical property
(e) physical property
(f) physical property
(a) chemical change
(b) physical change
(c) chemical change
(d) physical change
1.9 (a) Physical properties: color (colorless), physical state (liquid)
Chemical property: reactivity (burns in air)
(b) Physical properties: color (shiny metal, orange), physical state (liquid)
Chemical property: reactivity (aluminum reacts readily with bromine)
1.10 (a) Physical properties: color (white), physical state (solid), density (2.71 g/cm 3 )
Chemical properties: reactivity towards acid (reacts to produce gaseous carbon dioxide)
(b) Physical property: color (gray zinc, purple iodine, white compound)
Chemical property: reactivity (zinc and iodine react to give a white compound)
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Chapter 1 Basic Concepts of Chemistry
1.11. Mechanical energy is used to move the lever, producing electrical and radiant energy
1.12. Mechanical energy, electrical energy, radiant energy
1.13 (a) Kinetic energy
(b) Potential energy
(c) Potential energy
(d) Potential energy
1.14 (a) Potential energy converted to kinetic energy
(b) Kinetic energy converted to potential energy
(c) Potential energy converted to kinetic energy
(d) Kinetic energy converted to potential energy
1.15 (a) Qualitative observations: blue-green color, solid physical state
Quantitative observations: density of 2.65 g/cm 3 , mass of 2.5 g
(b) Mass is an extensive property; color, physical state, and density are intensive properties
1 cm
3
(c) 2.5 g ·
2.65 g
= 0.94 cm 3
1.16 (a) Qualitative observations: shiny golden metallic appearance, crystals in form of perfect cubes
Quantitative observations: length of 0.40 cm on a side, mass of 0.064 g
(b) Mass and length are extensive properties; color, luster, and crystalline form are intensive properties
(c) 0.064 g/(0.40 cm) 3 = 1.0 g/cm 3 = 1.0 g/mL
1.17 Observation (c) identifies a chemical property.
1.18 Observations (a) and (b) identify chemical properties.
1.19 Calcium: Ca Fluorine: F
The shape of the fluorite crystals can be described as interwoven cubes.
The overall shape of the crystals indicates that the ions in the solid matrix arrange themselves with alternating calcium and fluoride ions to produce the crystal appearance.
1.20 (a) Copper, Cu Carbon, C Oxygen: O
(b) Oxygen is a gas, while copper, carbon, and azurite are solids at room temperature. Oxygen is colorless, while copper has a reddish color and carbon is gray. The gemstone is a bluish color.
1.21 The non-uniform appearance of the mixture indicates that samples taken from different regions of the mixture would be different—a characteristic of a heterogeneous mixture. Recalling that iron is attracted to a magnetic field while sand is generally not attracted in this way suggests that passing a magnet through the
4

Chapter 1 Basic Concepts of Chemistry mixture would separate the sand and iron.
1.22 The water can be removed by boiling the solution until all the water is converted to water vapor; the solid left behind will be NaCl.
1.23 Physical changes: a, b, d
Chemical changes: c
1.24 Physical changes: a, d
Chemical changes: b, c
1.25 The large colorless block of salt represents the macroscopic view. The spheres represent the microscopic or particulate view. If one can imagine producing multiple “copies” of the particulate view, the macroscopic view will result.
1.26 The orange solid and liquid in the bowl and the orange liquid and gas in the round bottom flask represent the macroscopic views. The spheres represent the particulate view. The particulate view of the solid displays atoms of bromine tightly packed to produce the solid. The liquid view displays molecules of Br
2 with space separating the individual molecules. The gas view displays molecules of Br
2
; however, the molecules are further apart than in the liquid view.
1.27 The plastic (with a much lower density than CCl
4
) will float. The aluminum (which is more dense than
CCl
4
) will sink.
1.28 Liquids: mercury and water Solid: copper
Of the substances shown, mercury is most dense and water is least dense.
1.29 (a) mixture
(b) mixture
(c) element
(d) compound
1.30 (a) mixture
(b) compound
(c) mixture
(d) mixture
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Chapter 1
1.31 (a) solid iron (b) liquid water
Basic Concepts of Chemistry
(c) water vapor
1.32 (a) water vapor, helium (b) liquid water, solid aluminum (c) brass
1.33 The three liquids will be layered, with hexane floating on top of water, which in turn floats on top of the perfluorohexane. HDPE will lie at the top of the water layer. PVC will lie on top of the perfluorohexane layer. Teflon will sink to the bottom of the perfluorohexane layer.
1.34 Melting point. Sugar melts around 160–186 ºC while salt melts at 800 ºC.
1.35 HDPE will float in liquids with a density higher than 0.97 g/mL, ethylene glycol, water, acetic acid, and glycerol.
1.36 Milk is mostly water. When water freezes its volume increases (its density decreases). When the milk froze, the increase in volume was so great that it pushed out of the bottle.
1.37 The sample's density and melting point could be compared with that of silver to prove whether or not the sample is silver.
1.38 The mass of the object is determined and then the volume is determined by submersion in a known volume of liquid. The increase in volume would be equal to the volume of the irregularly shaped object. The density could be calculated by dividing its mass by its volume.
1.39 If too much sugar is excreted, the density of urine will increase. If too much water is excreted, the density of urine will decrease.
1.40 One could check for an odor, check the boiling or freezing point, or determine the density. If the density is approximately 1 g/cm 3 at room temperature, the liquid could be water. If it boils at about 100 ºC and freezes at about 0 ºC, that would be consistent with water. To check for the presence of salt, boil the liquid away. If a substance remains, it could be salt, but further testing would be required.
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Chapter 1 Basic Concepts of Chemistry
1.41 (a) Solid potassium reacts with liquid water to produce gaseous hydrogen and a homogeneous mixture of potassium hydroxide in liquid water.
(b) The reaction is a chemical change.
(c) Potassium and water are reactants, hydrogen and potassium hydroxide are products.
(d) Among the qualitative observations are (i) the reaction is violent; and (ii) heat and light (a purple flame) are produced.
1.42
Lea st dense liquid: water
Medium density: c arbon tetrachloride
Most dense liquid: me rcury
1.43 Any balloon filled with a gas having a density less than 1.12 g/L will float in air. Helium and neon balloons will float.
1.44 A copper-colored metal could be copper, but it may also be an alloy of copper, for example, brass or bronze. Testing the material’s density and melting temperature would be one way to find out if it is copper.
1.45 Physical change
1.46 (a) Mass CHCl
3
= 10.0 mL · 1.492 g/mL = 14.9 g
Mass CHBr
3
= 5.0 mL · 2.890 g/mL = 14 g
Mass of solution = 14.9 g + 14 g = 29 g
Density = mass of solution/volume of solution = 29 g/15.0 mL = 1.9 g/mL
(b) Mass of solution = 2.07 g/mL · 20.0 mL =41.4 g
Also, mass of solution = mass CHCl
3
+ mass CHBr
3
Let X = volume CHCl
3
and (20.0 mL - X) = volume CHBr
3
Then, mass of solution = (1.492 g/mL)X + (2.890 g/mL)(20.0 mL – X) = 41.4 g
X = 11.7 mL CHCl
3
(20.0 – X) = 8.3 mL CHBr
3
To obtain 20.0 mL of solution with d = 2.07 g/cm 3 , mix 11.7 mL CHCl
3
and 8.3 mL CHBr
3
.
7