Page 26

Chapter Summary

Section 1.1

is the study of*Chemistry*and the changes matter undergoes.*matter*Chemists go about research using a set of guidelines and practices known as the

in which observations give rise to*scientific method,*data give rise to*laws,*hypotheses are tested with experiments, and successful hypotheses give rise to*hypotheses,*which are further tested by experiment.*theories,*

Section 1.2

All matter exists either as a

or as a mixture of substances. Substances may be*substance*(containing only one kind of atom) or*elements*(containing two or more kinds of atoms). A*compounds*may be*mixture*(a solution) or*homogeneous*Mixtures may be separated using physical processes. Compounds can be separated into their constituent elements using chemical processes. Elements cannot be separated into simpler substances.*heterogeneous.*

Section 1.3

Scientists use a system of units referred to as the

or*International System of Units**SI units.*There are seven

*base*SI units including the kilogram (for) and the*mass*(for temperature). SI units for such quantities as volume and*kelvin*are derived from the base units.*density*

Section 1.4

Substances are identified by their

(involving numbers) and*quantitative*(not involving numbers) properties.*qualitative*are those that can be determined without the matter in question undergoing a chemical change. A*Physical properties*is one in which the identity of the matter involved does not change.*physical change*are determined only as the result of a*Chemical properties*in which the original substance is converted to a different substance. Physical and chemical properties may be*chemical change,*(dependent on the amount of matter) or*extensive*(independent of the amount of matter).*intensive*

Section 1.5

Measured numbers are

*inexact.*Numbers obtained by counting or that are part of a definition are*exact*numbers.are used to specify the uncertainty in a measured number or in a number calculated using measured numbers.*Significant figures*Significant figures must be carried through calculations such that the implied uncertainty in the final answer is reasonable.

refers to how close measured numbers are to a*Accuracy**true*value.refers to how close measured numbers are to*Precision**one another.*

Section 1.6

A

is a fraction in which the numerator and denominator are the same quantity expressed in different units.Multiplying by a conversion factor is*conversion factor**unit conversion.*is a series of unit conversions used in the solution of a multistep problem.*Dimensional analysis*

Key Words

Accuracy, 20
Chemical change, 15
Chemical property, 15
Chemistry, 4
Compound, 7
Conversion factor, 22
Density, 12
Dimensional analysis, 22
Element, 6
Extensive property, 15
Heterogeneous mixture, 8
Homogeneous mixture, 7
Hypothesis, 5
Intensive property, 15
International System of Units, 9
Kelvin, 10
Law, 5
Mass, 10
Matter, 4
Mixture, 7
Physical change, 15
Physical property, 14
Precision, 20
Qualitative property, 14
Quantitative property, 14
Scientific method, 5
Significant figures, 17
SI unit, 9
Substance, 6
Theory, 6

Key Equations

- 1.1
- 1.2
.

- 1.3
- 1.4

Page 27

Questions and Problems

Section 1.1: The Study of Chemistry

Review Questions

- 1.1
Define the terms

*chemistry*and*matter.* - 1.2
Explain what is meant by the scientific method.

- 1.3
What is the difference between a hypothesis and a theory?

Problems

- 1.4
Classify each of the following statements as a hypothesis, law, or theory. (a) Beethoven's contribution to music would have been much greater if he had married. (b) An autumn leaf gravitates toward the ground because there is an attractive force between the leaf and Earth. (c) All matter is composed of very small particles called atoms.

- 1.5
Classify each of the following statements as a hypothesis, law, or theory. (a) The force acting on an object is equal to its mass times its acceleration. (b) The universe as we know it started with a big bang. (c) There are many civilizations more advanced than ours on other planets.

- 1.6
Identify the elements present in the following molecules (see Table 1.1).

- 1.7
Identify the elements present in the following molecules (see Table 1.1).

Section 1.2: Classification of Matter

Review Questions

- 1.8
Give an example for each of the following terms: (a) matter, (b) substance, (c) mixture.

- 1.9
Give an example of a homogeneous mixture and an example of a heterogeneous mixture.

- 1.10
Give an example of an element and a compound. How do elements and compounds differ?

- 1.11
What is the number of known elements?

Problems

- 1.12
Give the names of the elements represented by the chemical symbols Li, F, P, Cu, As, Zn, Cl, Pt, Mg, U, Al, Si, Ne (see the table inside the front cover).

- 1.13
Give the chemical symbols for the following elements: (a) potassium, (b) tin, (c) chromium, (d) boron, (e) barium, (f) plutonium, (g) sulfur, (h) argon, (i) mercury (see the table inside the front cover).

- 1.14
Classify each of the following substances as an element or a compound: (a) hydrogen, (b) water, (c) gold, (d) sugar.

- 1.15
Classify each of the following as an element, a compound, a homogeneous mixture, or a heterogeneous mixture: (a) seawater, (b) helium gas, (c) sodium chloride (salt), (d) a bottle of soft drink, (e) a milkshake, (f) air in a bottle, (g) concrete.

- 1.16
Identify each of the diagrams shown here as a solid, liquid, gas, or mixture of two substances.

- 1.17
Identify each of the diagrams shown here as an element or a compound.

Section 1.3: Scientific Measurement

Review Questions

- 1.18
Name the SI base units that are important in chemistry, and give the SI units for expressing the following: (a) length, (b) volume, (c) mass, (d) time, (e) temperature.

- 1.19
Write the numbers represented by the following prefixes: (a) mega-, (b) kilo-, (c) deci-, (d) centi-, (e) milli-, (f) micro-, (g) nano-, (h) pico-.

- 1.20
What units do chemists normally use for the density of liquids and solids? For the density of gas? Explain the differences.

- 1.21
What is the difference between mass and weight? If a person weighs 168 lb on Earth, about how much would the person weigh on the moon?

- 1.22
Describe the three temperature scales used in the laboratory and in everyday life: the Fahrenheit, Celsius, and Kelvin scales.

Problems

- 1.23
Bromine is a reddish-brown liquid. Calculate its density (in g/mL) if 586 g of the substance occupies 188 mL.

- 1.24
The density of ethanol, a colorless liquid that is commonly known as grain alcohol, is 0.798 g/mL. Calculate the mass of 17.4 mL of the liquid.

- 1.25
Convert the following temperatures to degrees Celsius or Fahrenheit: (a) 95°F, the temperature on a hot summer day; (b) 12°F, the temperature on a cold winter day; (c) a 102°F fever; (d) a furnace operating at 1852°F; (e) −273.15°C (theoretically the lowest attainable temperature).

- 1.26
(a) Normally the human body can endure a temperature of 105°F for only short periods of time without permanent damage to the brain and other vital organs. What is this temperature in degrees Celsius? (b) Ethylene glycol is a liquid organic compound that is used as an antifreeze in car radiators. It freezes at −11.5°C. Calculate its freezing temperature in degrees Fahrenheit. (c) The temperature on the surface of the sun is about 6300°C. What is this temperature in degrees Fahrenheit?

- 1.27
The density of water at 40°C is 0.992 g/mL. What is the volume of 2.50 g of water at this temperature?

- 1.28
The density of platinum (Pt) is 21.5 g/cm

^{3}at 25°C. What is the volume of 87.6 g of Pt at this temperature? - 1.29
Convert the following temperatures to kelvin: (a) 115.21°C, the melting point of sulfur; (b) 37°C, the normal body temperature; (c) 357°C, the boiling point of mercury.

- 1.30
Convert the following temperatures to degrees Celsius: (a) 77 K, the boiling point of liquid nitrogen, (b) 4.22 K, the boiling point of liquid helium, (c) 600.61 K, the melting point of lead.

Page 28

Section 1.4: The Properties of Matter

Review Questions

- 1.31
What is the difference between qualitative data and quantitative data?

- 1.32
Using examples, explain the difference between a physical property and a chemical property.

- 1.33
How does an intensive property differ from an extensive property?

- 1.34
Determine which of the following properties are intensive and which are extensive: (a) length, (b) volume, (c) temperature, (d) mass.

Problems

- 1.35
Classify the following as qualitative or quantitative statements, giving your reasons. (a) The sun is approximately 93 million mi from Earth. (b) Leonardo da Vinci was a better painter than Michelangelo. (c) Ice is less dense than water. (d) Butter tastes better than margarine. (e) A stitch in time saves nine.

- 1.36
Determine whether the following statements describe chemical or physical properties: (a) Oxygen gas supports combustion. (b) Fertilizers help to increase agricultural production. (c) Water boils below 100°C on top of a mountain. (d) Lead is denser than aluminum. (e) Uranium is a radioactive element.

- 1.37
Determine whether each of the following describes a physical change or a chemical change: (a) The helium gas inside a balloon tends to leak out after a few hours. (b) A flashlight beam slowly gets dimmer and finally goes out. (c) Frozen orange juice is reconstituted by adding water to it. (d) The growth of plants depends on the sun's energy in a process called photosynthesis. (e) A spoonful of salt dissolves in a bowl of soup.

- 1.38
A student pours 44.3 g of water at 10°C into a beaker containing 115.2 g of water at 10°C. What are the final mass, temperature, and density of the combined water? The density of water at 10°C is 1.00 g/mL.

- 1.39
A 37.2-g sample of lead (Pb) pellets at 20°C is mixed with a 62.7-g sample of lead pellets at the same temperature. What are the final mass, temperature, and density of the combined sample? The density of Pb at 20°C is 11.35 g/cm

^{3}.

Section 1.5: Uncertainty in Measurement

Review Questions

- 1.40
Comment on whether each of the following statements represents an exact number: (a) 50,247 tickets were sold at a sporting event, (b) 509.2 mL of water was used to make a birthday cake, (c) 3 dozen eggs were used to make a breakfast, (d) 0.41 g of oxygen was inhaled in each breath, (e) Earth orbits the sun every 365.2564 days.

- 1.41
What is the advantage of using scientific notation over decimal notation?

- 1.42
Define

*significant figure.*Discuss the importance of using the proper number of significant figures in measurements and calculations. - 1.43
Distinguish between the terms

*accuracy*and*precision.*In general, explain why a precise measurement does not always guarantee an accurate result.

Problems

- 1.44
Express the following numbers in scientific notation: (a) 0.000000027, (b) 356, (c) 47,764, (d) 0.096.

- 1.45
Express the following numbers as decimals: (a) 1.52 × 10

^{−2}, (b) 7.78 × 10^{−8}, (c) 1 × 10^{−6}, (d) 1.6001 × 10^{3}. - 1.46
Express the answers to the following calculations in scientific notation:

145.75 + (2.3 × 10

^{−1})79,500 ÷ (2.5 × 10

^{2})(7.0 × 10

^{−3}) − (8.0 × 10^{−4})(1.0 × 10

^{4}) × (9.9 × 10^{6})

- 1.47
Express the answers to the following calculations in scientific notation:

0.0095 + (8.5 × 10

^{−3})653 ÷ (5.75 × 10

^{−8})850,000 − (9.0 × 10

^{5})(3.6 × 10

^{−4}) × (3.6 × 10^{6})

- 1.48
Determine the number of significant figures in each of the following measurements: (a) 4867 mi, (b) 56 mL, (c) 60,104 tons, (d) 2900 g, (e) 40.2 g/cm

^{3}, (f) 0.0000003 cm, (g) 0.7 min, (h) 4.6 × 10^{19}atoms. - 1.49
Determine the number of significant figures in each of the following measurements: (a) 0.006 L, (b) 0.0605 dm, (c) 60.5 mg, (d) 605.5 cm

^{2}, (e) 9.60 × 10^{3}g, (f) 6 kg, (g) 60 m. - 1.50
Carry out the following operations as if they were calculations of experimental results, and express each answer in the correct units with the correct number of significant figures:

5.6792 m + 0.6 m + 4.33 m

3.70 g − 2.9133 g

4.51 cm × 3.6666 cm

- 1.51
Carry out the following operations as if they were calculations of experimental results, and express each answer in the correct units with the correct number of significant figures:

7.310 km ÷ 5.70 km

(3.26 × 10

^{−3}mg) − (7.88 × 10^{−5}mg)(4.02 × 10

^{6}dm) + (7.74 × 10^{7}dm)

- 1.52
Three students (A, B, and C) are asked to determine the volume of a sample of ethanol. Each student measures the volume three times with a graduated cylinder. The results in milliliters are: A (87.1, 88.2, 87.6); B (86.9, 87.1, 87.2); C (87.6, 87.8, 87.9). The true volume is 87.0 mL. Comment on the precision and the accuracy of each student's results.

- 1.53
Three apprentice tailors (X, Y, and Z) are assigned the task of measuring the seam of a pair of trousers. Each one makes three measurements. The results in inches are X (31.5, 31.6, 31.4); Y (32.8, 32.3, 32,7); Z (31.9, 32.2, 32.1). The true length is 32.0 in. Comment on the precision and the accuracy of each tailor's measurements.

Page 29

Section 1.6: Using Units and Solving Problems

Problems

- 1.54
Carry out the following conversions: (a) 22.6 m to decimeters, (b) 25.4 mg to kilograms, (c) 556 mL to liters, (d) 10.6 kg/m

^{3}to g/cm^{3}. - 1.55
Carry out the following conversions: (a) 242 lb to milligrams, (b) 68.3 cm

^{3}to cubic meters, (c) 7.2 m^{3}to liters, (d) 28.3 μg to pounds. - 1.56
The average speed of helium at 25°C is 1255 m/s. Convert this speed to miles per hour (mph).

- 1.57
- 1.58
How many minutes does it take light from the sun to reach Earth? (The distance from the sun to Earth is 93 million mi; the speed of light is 3.00 × 10

^{8}m/s.) - 1.59
A slow jogger runs a mile in 13 min. Calculate the speed in (a) in/s, (b) m/min, (c) km/h (1 mi = 1609 m; 1 in = 2.54 cm).

- 1.60
A 6.0-ft person weighs 168 lb. Express this person's height in meters and weight in kilograms (1 lb = 453.6 g; 1 m = 3.28 ft).

- 1.61
The current speed limit in some states in the United States is 55 mph. What is the speed limit in kilometers per hour (1 mi = 1609 m)?

- 1.62
For a fighter jet to take off from the deck of an aircraft carrier, it must reach a speed of 62 m/s. Calculate the speed in miles per hour.

- 1.63
The “normal” lead content in human blood is about 0.40 part per million (that is, 0.40 g of lead per million grams of blood). A value of 0.80 part per million (ppm) is considered to be dangerous. How many grams of lead are contained in 6.0 × 10

^{3}g of blood (the amount in an average adult) if the lead content is 0.62 ppm? - 1.64
Carry out the following conversions: (a) 1.42 light-years to miles (a light-year is an astronomical measure of distance—the distance traveled by light in a year, or 365 days; the speed of light is 3.00 × 10

^{8}m/s), (b) 32.4 yd to centimeters, (c) 3.0 × 10^{10}cm/s to ft/s. - 1.65
Carry out the following conversions: (a) 185 nm to meters, (b) 4.5 billion years (roughly the age of Earth) to seconds (assume 365 days in a year), (c) 71.2 cm

^{3}to cubic meters, (d) 88.6 m^{3}to liters. - 1.66
Aluminum is a lightweight metal (density = 2.70 g/cm

^{3}) used in aircraft construction, high-voltage transmission lines, beverage cans, and foils. What is its density in kg/m^{3}? - 1.67
The density of ammonia gas under certain conditions is 0.625 g/L. Calculate its density in g/cm

^{3}. - 1.68
(a) Carbon monoxide (CO) is a poisonous gas because it binds very strongly to the oxygen carrier hemoglobin in blood. A concentration of 8.00 × 10

^{2}ppm by volume of carbon monoxide is considered lethal to humans. Calculate the volume in liters occupied by carbon monoxide in a room that measures 17.6 m long, 8.80 m wide, and 2.64 m high at this concentration. (b) Prolonged exposure to mercury (Hg) vapor can cause neurological disorder and respiratory problems. For safe air quality control, the concentration of mercury vapor must be under 0.050 mg/m^{3}. Convert this number to g/L. (c) The general test for type II diabetes is that the blood sugar (glucose) level should be below 120 mg per deciliter (mg/dL). Convert this number to micrograms per milliliter (μg/mL). - 1.69
The average time it takes for a molecule to diffuse a distance of

*x*cm is given bywhere

*t*is the time in seconds and*D*is the diffusion coefficient. Given that the diffusion coefficient of glucose is 5.7 × 10^{−7}cm^{2}/s, calculate the time it would take for a glucose molecule to diffuse 10 μm, which is roughly the size of a cell. - 1.70
A human brain weighs about 1 kg and contains about 10

^{11}cells. Assuming that each cell is completely filled with water (density = 1 g/mL), calculate the length of one side of such a cell if it were a cube. If the cells are spread out into a thin layer that is a single cell thick, what is the surface area in square meters?

Additional Problems

- 1.71
Using the appropriate number of significant figures, report the length of the blue rectangle (a) using the ruler shown above the rectangle and (b) using the ruler shown below the rectangle.

- 1.72
A piece of metal with a mass of 13.2 g was dropped into a graduated cylinder containing 17.00 mL of water. The graduated cylinder after the addition of the metal is shown. Determine the density of the metal to the appropriate number of significant figures.

- 1.73
Which of the following statements describe physical properties and which describe chemical properties? (a) Iron has a tendency to rust. (b) Rainwater in industrialized regions tends to be acidic. (c) Hemoglobin molecules have a red color. (d) When a glass of water is left out in the sun, the water gradually disappears. (e) Carbon dioxide in air is converted to more complex molecules by plants during photosynthesis.

- 1.74
In determining the density of a rectangular metal bar, a student made the following measurements: length, 8.53 cm; width, 2.4 cm; height, 1.0 cm; mass, 52.7064 g. Calculate the density of the metal to the correct number of significant figures.

- 1.75
Calculate the mass of each of the following: (a) a sphere of gold with a radius of 10.0 cm (volume of a sphere with a radius

*r*is*V*=; density of gold = 19.3 g/cm^{3}), (b) a cube of platinum of edge length 0.040 mm (density = 21.4 g/cm^{3}), (c) 50.0 mL of ethanol (density = 0.798 g/mL). - 1.76
A cylindrical glass tube 12.7 cm in length is filled with mercury (density = 13.6 g/mL). The mass of mercury needed to fill the tube is 105.5 g. Calculate the inner diameter of the tube (volume of a cylinder of radius

*r*and length*h*is*V*= π*r*^{2}*h*). - 1.77
The following procedure was used to determine the volume of a flask. The flask was weighed dry and then filled with water. If the masses of the empty flask and filled flask were 56.12 g and 87.39 g, respectively, and the density of water is 0.9976 g/cm

^{3}, calculate the volume of the flask in cubic centimeters. - 1.78
The speed of sound in air at room temperature is about 343 m/s. Calculate this speed in miles per hour (1 mi = 1609 m).

- 1.79
A piece of silver (Ag) metal weighing 194.3 g is placed in a graduated cylinder containing 242.0 mL of water. The volume of water now reads 260.5 mL. From these data calculate the density of silver.

- 1.80
The experiment described in Problem 1.79 is a crude but convenient way to determine the density of some solids. Describe a similar experiment that would enable you to measure the density of ice. Specifically, what would be the requirements for the liquid used in your experiment?

- 1.81
A lead sphere has a mass of 1.20 × 10

^{4}g, and its volume is 1.05 × 10^{3}cm^{3}. Calculate the density of lead. - 1.82
Lithium is the least dense metal known (density = 0.53 g/cm

^{3}). What is the volume occupied by 1.20 × 10^{3}g of lithium? - 1.83
The medicinal thermometer commonly used in homes can be read to ±0.1°F, whereas those in the doctor's office may be accurate to ±0.1°C. Percent error is often expressed as the absolute value of the difference between the true value and the experimental value, divided by the true value:

The vertical lines indicate absolute value. In degrees Celsius, express the percent error expected from each of these thermometers in measuring a person's body temperature of 38.9°C.

- 1.84
Vanillin (used to flavor vanilla ice cream and other foods) is the substance whose aroma the human nose detects in the smallest amount. The threshold limit is 2.0 × 10

^{−11}g per liter of air. If the current price of 50 g of vanillin is $112, determine the cost to supply enough vanillin so that the aroma could be detected in a large aircraft hangar with a volume of 5.0 × 10^{7}ft^{3}. - 1.85
At what temperature does the numerical reading on a Celsius thermometer equal that on a Fahrenheit thermometer?

- 1.86
Suppose that a new temperature scale has been devised on which the melting point of ethanol (−117.3°C) and the boiling point of ethanol (78.3°C) are taken as 0°S and 100°S, respectively, where S is the symbol for the new temperature scale. Derive an equation relating a reading on this scale to a reading on the Celsius scale. What would this thermometer read at 25°C?

- 1.87
A resting adult requires about 240 mL of pure oxygen per minute and breathes about 12 times every minute. If inhaled air contains 20 percent oxygen by volume and exhaled air 16 percent, what is the volume of air per breath? (Assume that the volume of inhaled air is equal to that of exhaled air.)

- 1.88
(a) Referring to Problem 1.87, calculate the total volume (in liters) of air an adult breathes in a day. (b) In a city with heavy traffic, the air contains 2.1 × 10

^{−6}L of carbon monoxide (a poisonous gas) per liter. Calculate the average daily intake of carbon monoxide in liters by a person. - 1.89
The total volume of seawater is 1.5 × 10

^{21}L. Assume that seawater contains 3.1 percent sodium chloride by mass and that its density is 1.03 g/mL. Calculate the total mass of sodium chloride in kilograms and in tons (1 ton = 2000 lb; 1 lb = 453.6 g). - 1.90
Magnesium (Mg) is a valuable metal used in alloys, in batteries, and in the manufacture of chemicals. It is obtained mostly from seawater, which contains about 1.3 g of Mg for every kilogram of seawater. Referring to Problem 1.89, calculate the volume of seawater (in liters) needed to extract 8.0 × 10

^{4}tons of Mg, which is roughly the annual production in the United States. - 1.91
A student is given a crucible and asked to prove whether it is made of pure platinum. She first weighs the crucible in air and then weighs it suspended in water (density = 0.9986 g/mL). The readings are 860.2 g and 820.2 g, respectively. Based on these measurements and given that the density of platinum is 21.45 g/cm

^{3}, what should her conclusion be? (*Hint:*An object suspended in a fluid is buoyed up by the mass of the fluid displaced by the object. Neglect the buoyancy of air.) - 1.92
The surface area and average depth of the Pacific Ocean are 1.8 × 10

^{8}km^{2}and 3.9 × 10^{3}m, respectively. Calculate the volume of water in the ocean in liters. - 1.93
The unit “troy ounce” is often used for precious metals such as gold (Au) and platinum (Pt) (1 troy ounce = 31.103 g). (a) A gold coin weighs 2.41 troy ounces. Calculate its mass in grams. (b) Is a troy ounce heavier or lighter than an ounce (1 lb = 16 oz; 1 lb = 453.6 g)?

- 1.94
Osmium (Os) is the densest element known (density = 22.57 g/cm

^{3}). Calculate the mass in pounds and in kilograms of an Os sphere 15 cm in diameter (about the size of a grapefruit) (volume of a sphere of radius*r*is ). - 1.95
Calculate the percent error for the following measurements: (a) The density of alcohol (ethanol) is found to be 0.802 g/mL (true value = 0.798 g/mL). (b) The mass of gold in an earring is analyzed to be 0.837 g (true value = 0.864 g).

- 1.96
The natural abundances of elements in the human body, expressed as percent by mass, are oxygen (O), 65 percent; carbon (C), 18 percent; hydrogen (H), 10 percent; nitrogen (N), 3 percent; calcium (Ca), 1.6 percent; phosphorus (P), 1.2 percent; all other elements, 1.2 percent. Calculate the mass in grams of each element in the body of a 62-kg person.

- 1.97
The men's world record for running a mile outdoors (as of 1999) is 3 min 43.13 s. At this rate, how long would it take to run a 1500-m race (1 mi = 1609 m)?

- 1.98
Venus, the second closest planet to the sun, has a surface temperature of 7.3 × 10

^{2}K. Convert this temperature to degrees Celsius and degrees Fahrenheit. - 1.99
Chalcopyrite, the principal ore of copper (Cu), contains 34.63 percent Cu by mass. How many grams of Cu can be obtained from 5.11 × 10

^{3}kg of the ore? - 1.100
It has been estimated that 8.0 × 10

^{4}tons of gold (Au) have been mined. Assume gold costs $900 per Troy ounce. What is the total worth of this quantity of gold? (1 Troy ounce = 31.103 g) - 1.101
A 1.0-mL volume of seawater contains about 4.0 × 10

^{−12}g of gold. The total volume of ocean water is 1.5 × 10^{21}L. Calculate the total amount of gold (in grams) that is present in seawater and the worth of the gold in dollars (see Problem 1.100). With so much gold out there, why hasn't someone become rich by mining gold from the ocean? - 1.102
Measurements show that 1.0 g of iron (Fe) contains 1.1 × 10

^{22}Fe atoms. How many Fe atoms are in 4.9 g of Fe, which is the total amount of iron in the body of an average adult? - 1.103
The thin outer layer of Earth, called the crust, contains only 0.50 percent of Earth's total mass and yet is the source of almost all the elements (the atmosphere provides elements such as oxygen, nitrogen, and a few other gases). Silicon (Si) is the second most abundant element in Earth's crust (27.2 percent by mass). Calculate the mass of silicon in kilograms in Earth's crust (mass of Earth = 5.9 × 10

^{21}tons; 1 ton = 2000 lb; 1 lb = 453.6 g). - 1.104
The radius of a copper (Cu) atom is roughly 1.3 × 10

^{−10}m. How many times can you divide evenly a 10-cm-long piece of copper wire until it is reduced to two separate copper atoms? (Assume there are appropriate tools for this procedure and that copper atoms are lined up in a straight line, in contact with each other. Round off your answer to an integer.) - 1.105
One gallon of gasoline in an automobile's engine produces on the average 9.5 kg of carbon dioxide, which is a greenhouse gas; that is, it promotes the warming of Earth's atmosphere. Calculate the annual production of carbon dioxide in kilograms if there are 40 million cars in the United States and each car covers a distance of 5000 mi at a consumption rate of 20 miles per gallon.

- 1.106
A sheet of aluminum (Al) foil has a total area of 1.000 ft

^{2}and a mass of 3.636 g. What is the thickness of the foil in millimeters (density of Al = 2.699 g/cm^{3})? - 1.107
Comment on whether each of the following is a homogeneous mixture or a heterogeneous mixture: (a) air in a closed bottle, (b) air over New York City.

- 1.108
Chlorine is used to disinfect swimming pools. The accepted concentration for this purpose is 1 ppm chlorine, or 1 g of chlorine per million grams of water. Calculate the volume of a chlorine solution (in milliliters) a homeowner should add to her swimming pool if the solution contains 6.0 percent chlorine by mass and there are 2.0 × 10

^{4}gallons (gal) of water in the pool (1 gal = 3.79 L; density of liquids = 1.0 g/mL). - 1.109
The world's total petroleum reserve is estimated at 2.0 × 10

^{22}joules [a joule (J) is the unit of energy where 1 J = 1 kg · m^{2}/s^{2}]. At the present rate of consumption, 1.8 × 10^{20}joules per year (J/yr), how long would it take to exhaust the supply? - 1.110
In water conservation, chemists spread a thin film of a certain inert material over the surface of water to cut down on the rate of evaporation of water in reservoirs. This technique was pioneered by Benjamin Franklin three centuries ago. Franklin found that 0.10 mL of oil could spread over the surface of water about 40 m

^{2}in area. Assuming that the oil forms a*monolayer,*that is, a layer that is only one molecule thick, estimate the length of each oil molecule in nanometers (1 nm = 1 × 10^{−9}m). - 1.111
Fluoridation is the process of adding fluorine compounds to drinking water to help fight tooth decay. A concentration of 1 ppm of fluorine is sufficient for the purpose (1 ppm means one part per million, or 1 g of fluorine per 1 million g of water). The compound normally chosen for fluoridation is sodium fluoride, which is also added to some toothpastes. Calculate the quantity of sodium fluoride in kilograms needed per year for a city of 50,000 people if the daily consumption of water per person is 150 gal. What percent of the sodium fluoride is “wasted” if each person uses only 6.0 L of water a day for drinking and cooking (sodium fluoride is 45.0 percent fluorine by mass; 1 gal = 3.79 L; 1 year = 365 days; 1 ton = 2000 lb; 1 lb = 453.6 g; density of water = 1.0 g/mL)?

- 1.112
A gas company in Massachusetts charges $1.30 for 15.0 ft

^{3}of natural gas. (a) Convert this rate to dollars per liter of gas. (b) If it takes 0.304 ft^{3}of gas to boil a liter of water, starting at room temperature (25°C), how much would it cost to boil a 2.1-L kettle of water? - 1.113
Pheromones are compounds secreted by females of many insect species to attract mates. Typically, 1.0 × 10

^{−8}g of a pheromone is sufficient to reach all targeted males within a radius of 0.50 mi. Calculate the density of the pheromone (in grams per liter) in a cylindrical air space having a radius of 0.50 mi and a height of 40 ft (volume of a cylinder of radius*r*and height*h*is π*r*^{2}*h*). - 1.114
A bank teller is asked to assemble $1 sets of coins for his clients. Each set is made up of three quarters, one nickel, and two dimes. The masses of the coins are quarter, 5.645 g; nickel, 4.967 g; and dime, 2.316 g. What is the maximum number of sets that can be assembled from 33.871 kg of quarters, 10.432 kg of nickels, and 7.990 kg of dimes? What is the total mass (in grams) of the assembled sets of coins?

- 1.115
A graduated cylinder is filled to the 40.00-mL mark with a mineral oil. The masses of the cylinder before and after the addition of the mineral oil are 124.966 g and 159.446 g, respectively. In a separate experiment, a metal ball bearing of mass 18.713 g is placed in the cylinder and the cylinder is again filled to the 40.00-mL mark with the mineral oil. The combined mass of the ball bearing and mineral oil is 50.952 g. Calculate the density and radius of the ball bearing (volume of a sphere of radius

*r*is ). - 1.116
Bronze is an alloy made of copper (Cu) and tin (Sn). Calculate the mass of a bronze cylinder of radius 6.44 cm and length 44.37 cm. The composition of the bronze is 79.42 percent Cu and 20.58 percent Sn and the densities of Cu and Sn are 8.94 g/cm

^{3}and 7.31 g/cm^{3}, respectively. What assumption should you make in this calculation? - 1.117
A chemist in the nineteenth century prepared an unknown substance. In general, do you think it would be more difficult to prove that it is an element or a compound? Explain.

- 1.118
A chemist mixes two liquids A and B to form a homogeneous mixture. The densities of the liquids are 2.0514 g/mL for A and 2.6678 g/mL for B. When she drops a small object into the mixture, she finds that the object becomes suspended in the liquid; that is, it neither sinks nor floats. If the mixture is made of 41.37 percent A and 58.63 percent B by volume, what is the density of the object? Can this procedure be used in general to determine the densities of solids? What assumptions must be made in applying this method?

- 1.119
You are given a liquid. Briefly describe the steps you would take to show whether it is a pure substance or a homogeneous mixture.

- 1.120
TUMS is a popular remedy for acid indigestion. A typical TUMS tablet contains calcium carbonate plus some inert substances. When ingested, it reacts with the gastric juice (hydrochloric acid) in the stomach to give off carbon dioxide gas. When a 1.328-g tablet reacted with 40.00 mL of hydrochloric acid (density = 1.140 g/mL), carbon dioxide gas was given off and the resulting solution weighed 46.699 g. Calculate the number of liters of carbon dioxide gas released if its density is 1.81 g/L.

- 1.121
A 250-mL glass bottle was filled with 242 mL of water at 20°C and tightly capped. It was then left outdoors overnight, where the average temperature was −5°C. Predict what would happen. The density of water at 20°C is 0.998 g/cm

^{3}and that of ice at −5°C is 0.916 g/cm^{3}.

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Pre-Professional Practice Exam Problems: Verbal Reasoning

English writer and essayist Lady Mary Wortley Montagu (1689–1762) traveled extensively and was fascinated by the customs in other countries. While in Turkey, she observed the practice of “engrafting” wherein people were inoculated against smallpox by intentional exposure to a mild form of the disease. She was so convinced of the efficacy and the safety of engrafting, that she had both of her children inoculated. She herself had survived smallpox as a child. Lady Montagu campaigned for the practice when she returned to England, and despite opposition from doctors and religious leaders, inoculation came into common use. It remained the primary defense against the scourge of smallpox for decades—until Jenner developed the practice of vaccination.

The main point of the passage is that

Lady Montagu survived smallpox as a child.

Lady Montagu brought the practice of engrafting from Turkey to England.

Doctors in eighteenth-century England were opposed to the practice of engrafting.

Jenner developed the practice of vaccination.

Based on the passage, Lady Montagu was most likely

a doctor.

Turkish.

severely scarred by smallpox.

a member of a prominent British family.

The author refers to Lady Montagu having survived smallpox to

explain why Lady Montagu was fascinated by the practice of engrafting.

compare Lady Montagu to the doctors and religious leaders in England.

explain why Lady Montagu herself did not undergo the engrafting procedure.

emphasize Lady Montagu's fascination with other cultures.

Based on the passage, the author most likely thinks that Lady Montagu was

educated and influential.

inconsequential in the prevention of smallpox in England.

trained in science and medicine.

married to the British ambassador to Turkey.

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Answers to In-Chapter Materials

Practice Problems

- 1.1A
273 K and 373 K, range = 100 K.

- 1.1B
−270.5°C.

- 1.2A
113°F, 194°F; difference = 81°F.

- 1.2B
233°C.

- 1.3A
14 g/mL,

1.6 × 10

^{3}g.

- 1.3B
9.25 g/cm

^{3},3.76 × 10

^{3}g.

- 1.4A
(a) and (c).

- 1.4B
iii, i.

- 1.5A
4,

1,

4,

2,

2 or 3,

4.

- 1.5B
4,

5,

4,

3,

ambiguous,

5.

- 1.6A
116.2 L,

80.71 m,

3.813 × 10

^{21}atoms,31 dm

^{2},0.504 g/mL.

- 1.6B
32.44 cm

^{3},4.2 × 10

^{2}kg/m^{3},1.008 × 10

^{10}kg,40.75 mL,

227 cm

^{3}.

- 1.7A
0.8120 g/cm

^{3}. - 1.7B
95.3 cm

^{3}. - 1.8A
0.01 oz.

- 1.8B
0.8813 oz.

- 1.9A
1.05 × 10

^{4}kg/m^{3}. - 1.9B
13.6 mg/mm

^{3}.

Checkpoints

- 1.3.1
c.

- 1.3.2
a.

- 1.3.3
b.

- 1.3.4
d.

- 1.4.1
b, c, e.

- 1.4.2
a, d, f.

- 1.5.1
c.

- 1.5.2
e.

- 1.5.3
c.

- 1.5.4
e.

- 1.6.1
b.

- 1.6.2
c.

- 1.6.3
a.

- 1.6.4
e.

Applying What You've Learned

The recommended storage-temperature range for cidofovir is 20°C−25°C.

The density of the fluid in a vial is 1.18 g/mL. (The density should be reported to three significant figures.)

The recommended dosage of cidofovir for a 177-lb man is 4 × 10

^{2}mg or 0.4 g.1.18 × 10

^{3}g/L, 1.18 × 10^{3}kg/m^{3}.