Chapter 1

Musical instruments like trumpets and trombones are made from an alloy called brass. Brass is composed of copper and zinc atoms and appears homogeneous under an optical microscope. The approximate composition of most brass objects is a 2: 1 ratio of copper to zinc atoms, but the exact ratio varies somewhat from one piece of brass to another. (a) Would you classify brass as an element, a compound, a homogeneous mixture, or a heterogeneous mixture? (b) Would it be correct to say that brass is a solution?

Is the separation method used in brewing a cup of coffee best described as distillation, filtration, or chromatography?

Identify each of the following as measurements of length, area, volume, mass, density, time, or temperature: (a) \(25 \mathrm{ps}\), (b) \(374.2 \mathrm{mg}\), (c) \(77 \mathrm{~K}\), (d) \(100,000 \mathrm{~km}^{2}\), (e) \(1.06 \mu \mathrm{m}\), (f) \(16 \mathrm{nm}^{2},(\mathbf{g})-78^{\circ} \mathrm{C},(\mathbf{h}) 2.56 \mathrm{~g} / \mathrm{cm}^{3}\), (i) \(28 \mathrm{~cm}^{3}\).

(a) Three spheres of equal size are composed of aluminum \(\left(\right.\) density \(\left.=2.70 \mathrm{~g} / \mathrm{cm}^{3}\right),\) silver \(\left(\right.\) density \(\left.=10.49 \mathrm{~g} / \mathrm{cm}^{3}\right)\) and nickel (density \(\left.=8.90 \mathrm{~g} / \mathrm{cm}^{3}\right) .\) List the spheres from lightest to heaviest. (b) Three cubes of equal mass are composed of gold (density \(\left.=19.32 \mathrm{~g} / \mathrm{cm}^{3}\right),\) platinum (density \(\left.=21.45 \mathrm{~g} / \mathrm{cm}^{3}\right),\) and lead \(\left(\right.\) density \(\left.=11.35 \mathrm{~g} / \mathrm{cm}^{3}\right)\) List the cubes from smallest to largest.

Consider the jar of jelly beans in the photo. To get an estimate of the number of beans in the jar you weigh six beans and obtain masses of \(3.15,3.12,2.98,3.14,3.02,\) and \(3.09 \mathrm{~g}\). Then you weigh the jar with all the beans in it, and obtain a mass of \(2082 \mathrm{~g}\). The empty jar has a mass of \(653 \mathrm{~g}\). Based on these data, estimate the number of beans in the jar. Justify the number of significant figures you use in your estimate.

Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (a) air, (b) chocolate with almond, (c) aluminium, (d) iodine tincture.

Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (a) milk, (b) beer, (c) diamond, (d) mayonnaise.

Give the chemical symbol or name for the following elements, as appropriate: (a) helium, (b) platinum, (c) cobalt, (d) \(t\) in, (e) silver, (f) Sb, \((\mathbf{g}) \mathrm{Pb}\), (h) \(\mathrm{Br}\) \(\mathrm{r},(\mathbf{i}) \mathrm{V},(\mathbf{j}) \mathrm{Hg}\).

Give the chemical symbol or name for each of the following elements, as appropriate: (a) rhenium, (b) tungsten, \((\mathbf{c})\) caesium, (d) hydrogen, (e) indium, (f) As, \((\mathbf{g})\) Xe, \((\mathbf{h}) \mathrm{Kr},(\mathbf{i})\) Te, (j) Ge.

A solid white substance A is heated strongly in the absence of air. It decomposes to form a new white substance \(\mathrm{B}\) and a gas \(\mathrm{C}\). The gas has exactly the same properties as the product obtained when carbon is burned in an excess of oxygen. Based on these observations, can we determine whether solids A and \(\mathrm{B}\) and gas \(\mathrm{C}\) are elements or compounds?

Zirconia, an oxide of zirconium, is often used as an affordable diamond substitute. Just like diamond, it is a colorless crystal which sparkles under sunlight. Which of the following physical properties do you think would help in differentiating between diamond and Zirconia-melting point, density, or physical state?

In the process of attempting to characterize a substance, a chemist makes the following observations: The substance is a silvery white, lustrous metal. It melts at \(649^{\circ} \mathrm{C}\) and boils at \(1105^{\circ} \mathrm{C}\). Its density at \(20^{\circ} \mathrm{C}\) is \(1.738 \mathrm{~g} / \mathrm{cm}^{3}\). The substance burns in air, producing an intense white light. It reacts with chlorine to give a brittle white solid. The substance can be pounded into thin sheets or drawn into wires. It is a good conductor of electricity. Which of these characteristics are physical properties, and which are chemical properties?

(a) Read the following description of the element zinc and indicate which are physical properties and which are chemical properties. Zinc melts at \(420^{\circ} \mathrm{C}\). When zinc granules are added to dilute sulfuric acid, hydrogen is given off and the metal dissolves. Zinc has a hardness on the Mohs scale of 2.5 and a density of \(7.13 \mathrm{~g} / \mathrm{cm}^{3}\) at \(25^{\circ} \mathrm{C}\). It reacts slowly with oxygen gas at elevated temperatures to form zinc oxide, \(\mathrm{ZnO}\). (b) Which properties of zinc can you describe from the photo? Are these physical or chemical properties?

Label each of the following as either a physical process or a chemical process: (a) crushing a metal can, (b) production of urine in the kidneys, \((\mathbf{c})\) melting a piece of chocolate, \((\mathbf{d})\) burning fossil fuel, (e) discharging a battery.

A match is lit to light a candle. The following observations are made: (a) The candle burns. (b) Some wax melts. (c) Melted wax solidifies on the candleholder. (d) Soot (carbon) is produced by the burning of the match and the candle. Which of these occurrences are due to physical changes, and which are due to chemical changes?

Which separation method is better suited for obtaining sugar from cane juice- filtration or evaporation?

A silvery metal is put inside a beaker of water. Bubbles form on the surface of the metal and it dissolves gradually. (a) Is this an example of a chemical or a physical change? (b) Do you expect the remaining solution to be a pure substance or a mixture?

(a) Calculate the kinetic energy, in joules, of a 15 -g bullet moving at \(120 \mathrm{~m} / \mathrm{s}\). (b) Convert this energy to calories. (c) When the bullet is stopped by a bulletproof vest, which form of energy does the kinetic energy of the bullet convert to?

(a) A baseball weighs \(145.4 \mathrm{~g}\). What is the kinetic energy, in joules, of this baseball when it is thrown by a major league pitcher at \(150 \mathrm{~km} / \mathrm{h} ?(\mathbf{b})\) By what factor will the kinetic energy change if the speed of the baseball is decreased to \(90 \mathrm{~km} / \mathrm{h} ?\) (c) What happens to the kinetic energy when the baseball is caught by the catcher? Is it converted mostly to heat or to some form of potential energy?

Two positively charged particles are first brought close together and then released. Once released, the repulsion between particles causes them to move away from each other. (a) This is an example of potential energy being converted into what form of energy? (b) Does the potential energy of the two particles prior to release increase or decrease as the distance between them is increased.

For each of the following processes, does the potential energy of the object(s) increase or decrease? (a) The charge of two oppositely charged particles is increased. (b) \(\mathrm{H}_{2} \mathrm{O}\) molecule is split into two oppositely charged ions, \(\mathrm{H}^{+}\) and \(\mathrm{OH}^{-}\). (c) A person skydives from a height of 600 meters.

Convert the following expressions into exponential notation: (a) 3 terameters (tm) (b) 2.5 femtoseconds (fs) (c) 57 micrometers \((\mu m)\) (d) 8.3 megagrams (mg).

Use appropriate metric prefixes to write the following measurements without use of exponents: (a) \(7.29 \times 10^{6} \mathrm{~g}\) (b) \(6.1 \times 10^{-10} \mathrm{~m}\) (c) \(1.828 \times 10^{-3} \mathrm{~s}\) (d) \(3.523 \times 10^{9} \mathrm{~m}^{3}\) (e) \(9.62 \times 10^{2} \mathrm{~m} / \mathrm{s}\) (f) \(8.923 \times 10^{-12} \mathrm{~kg}(\mathrm{~g}) 3.552 \times 10^{12} \mathrm{~L}\).

Make the following conversions: (a) \(83^{\circ} \mathrm{F}\) to \({ }^{\circ} \mathrm{C}\) (b) \(29^{\circ} \mathrm{C}\) to \({ }^{\circ} \mathrm{F}\) (c) \(294^{\circ} \mathrm{C}\) to \(\mathrm{K}\) (d) \(832 \mathrm{~K}\) to \({ }^{\circ} \mathrm{C}\) (e) \(721 \mathrm{~K}\) to \({ }^{\circ} \mathrm{F}\) (f) \(35^{\circ} \mathrm{F}\) to \(\mathrm{K}\).

(a) A child has a fever of \(101^{\circ} \mathrm{F}\). What is the temperature in \({ }^{\circ} \mathrm{C} ?\) (b) In a desert, the temperature can be as high as \(45^{\circ} \mathrm{C},\) what is the temperature in \({ }^{\circ}\) ? (c) During winter, the temperature of the Arctic region can drop below \(-50^{\circ} \mathrm{C},\) what is the temperature in degree Fahrenheit and in Kelvin? (d) The sublimation temperature of dry ice is \(-78.5^{\circ} \mathrm{C}\). Convert this temperature to degree Fahrenheit and Kelvin. (e) Ethanol boils at \(351 \mathrm{~K}\). Convert this temperature to degree Fahrenheit and degree Celsius.

(a) A sample of tetrachloroethylene, a liquid used in dry cleaning that is being phased out because of its potential to cause cancer, has a mass of \(40.55 \mathrm{~g}\) and a volume of \(25.0 \mathrm{~mL}\) at \(25^{\circ} \mathrm{C}\). What is its density at this temperature? Will tetrachloroethylene float on water? (Materials that are less dense than water will float.) (b) Carbon dioxide \(\left(\mathrm{CO}_{2}\right)\) is a gas at room temperature and pressure. However, carbon dioxide can be put under pressure to become a "supercritical fluid" that is a much safer dry-cleaning agent than tetrachloroethylene. At a certain pressure, the density of supercritical \(\mathrm{CO}_{2}\) is \(0.469 \mathrm{~g} / \mathrm{cm}^{3} .\) What is the mass of a 25.0-mL sample of supercritical \(\mathrm{CO}_{2}\) at this pressure?

(a) What is the mass of a silver cube whose edges measure 2.00 \(\mathrm{cm}\) each at \(25^{\circ} \mathrm{C} ?\) The density of silver is \(10.49 \mathrm{~g} / \mathrm{cm}^{3}\) at \(25^{\circ} \mathrm{C}\). (b) The density of aluminum is \(2.70 \mathrm{~g} / \mathrm{cm}^{3}\) at \(25^{\circ} \mathrm{C}\). What is the weight of the aluminum foil with an area of \(0.5 \mathrm{~m}^{2}\) and a thickness of \(0.5 \mathrm{~mm} ?\) (c) The density of hexane is \(0.655 \mathrm{~g} / \mathrm{mL}\) at \(25^{\circ} \mathrm{C} .\) Calculate the mass of \(1.5 \mathrm{~L}\) of hexane at this temperature.

(a) After the label fell off a bottle containing a clear liquid believed to be benzene, a chemist measured the density of the liquid to verify its identity. A 25.0-mL portion of the liquid had a mass of 21.95 g. A chemistry handbook lists the density of benzene at \(15^{\circ} \mathrm{C}\) as \(0.8787 \mathrm{~g} / \mathrm{mL}\). Is the calculated density in agreement with the tabulated value? (b) An experiment requires \(15.0 \mathrm{~g}\) of cyclohexane, whose density at \(25^{\circ} \mathrm{C}\) is \(0.7781 \mathrm{~g} / \mathrm{mL}\). What volume of cyclohexane should be used? (c) A spherical ball of lead has a diameter of \(5.0 \mathrm{~cm}\). What is the mass of the sphere if lead has a density of \(11.34 \mathrm{~g} / \mathrm{cm}^{3}\) ? (The volume of a sphere is \((4 / 3) \pi r^{3},\) where \(r\) is the radius. \()\)

If on a certain year, an estimated amount of 4 million metric tons (1 metric ton \(=1000 \mathrm{~kg}\) ) of nitrous oxide \(\left(\mathrm{N}_{2} \mathrm{O}\right)\) was emitted worldwide due to agricultural activities, express this mass of \(\mathrm{N}_{2} \mathrm{O}\) in grams without exponential notation, using an appropriate mètric préfix.

Silicon for computer chips is grown in large cylinders called "boules" that are \(300 \mathrm{~mm}\) in diameter and \(2 \mathrm{~m}\) in length, as shown. The density of silicon is \(2.33 \mathrm{~g} / \mathrm{cm}^{3}\). Silicon wafers for making integrated circuits are sliced from a \(2.0-\mathrm{m}\) boule and are typically \(0.75 \mathrm{~mm}\) thick and \(300 \mathrm{~mm}\) in diameter. (a) How many wafers can be cut from a single boule? (b) What is the mass of a silicon wafer? (The volume of a cylinder is given by \(\pi r^{2} h,\) where \(r\) is the radius and \(h\) is its height.)

Use of the British thermal unit (Btu) is common in some types of engineering work. A Btu is the amount of heat required to raise the temperature of \(1 \mathrm{lb}\) of water by \(1^{\circ} \mathrm{F}\). Calculate the number of joules in a Btu.

A watt is a measure of power (the rate of energy change) equal to \(1 \mathrm{~J} / \mathrm{s}\). (a) Calculate the number of joules in a kilowatt- hour. (b) An adult person radiates heat to the surroundings at about the same rate as a 100-watt electric incandescent light bulb. What is the total amount of energy in kcal radiated to the surroundings by an adult over a 24 h period?

Indicate which of the following are exact numbers: (a) the mass of a 7.5 - by \(12.5-\mathrm{cm}\) index card, \((\mathbf{b})\) the number of grams in a kilogram, \((\mathbf{c})\) the volume of a cup of Seattle's Best coffee, (d) the number of centimeters in a kilometer, (e) the number of microseconds in a week, (f) the number of pages in this book.

Indicate which of the following are exact numbers: (a) the mass of a 945-mL can of coffee, \((\mathbf{b})\) the number of students in your chemistry class, \((\mathbf{c})\) the temperature of the surface of the \(\operatorname{Sun},(\mathbf{d})\) the mass of a postage stamp, \((\mathbf{e})\) the number of milliliters in a cubic meter of water, \((\mathbf{f})\) the average height of \(\mathrm{NBA}\) basketball players.

What is the number of significant figures in each of the following measured quantities? (a) \(902.5 \mathrm{~kg}\), (b) \(3 \times 10^{-6} \mathrm{~m}\) (c) \(0.0096 \mathrm{~L}\), (d) \(2.94 \times 10^{3} \mathrm{~m}^{2}\) (e) \(92.03 \mathrm{~km}\) (f) \(782.234 \mathrm{~g}\).

Indicate the number of significant figures in each of the following measured quantities: (a) \(62.65 \mathrm{~km} / \mathrm{hr}\), (b) \(78.00 \mathrm{~K}\), (c) \(36.9 \mathrm{~mL}\), (d) \(250 \mathrm{~mm}\), (e) 89.2 metric tons, (f) \(6.4224 \times 10^{2} \mathrm{~m}^{3}\).

Round each of the following numbers to three significant figures and express the result in standard exponential no- tation: (a) 2048732.23 (b) 0.000292945 (c) -82454.09 (d) \(942.057024(\mathbf {e})-0.00000324683 .\)

(a) The diameter of Earth at the equator is \(12756.27 \mathrm{~km}\). Round this number to three significant figures and express it in standard exponential notation. (b) The circumference of Earth through the poles is \(40,008 \mathrm{~km}\). Round this number to four significant figures and express it in standard exponential notation.

Carry out the following operations and express the answers with the appropriate number of significant numbers. (a) \(43.029+0.02348\) (b) \(952.72-73.4201\) (c) \(\left(2.93 \times 10^{3}\right)(0.732)\) (d) \(0.06324 / 0.624\)

Carry out the following operations and express the answers with the appropriate number of significant numbers. (a) \((6.234+8.72) \times 0.6746\) (b) \(732.1-(892.5 / 8.2)\) (c) \(\left[\left(3.696 \times 10^{5}\right)-\left(6.234 \times 10^{3}\right)\right] \times 0.0742\) (d) \(0.006438 \times 108-(8.639+8.52)\)

(a) A bumblebee flies with a ground speed of \(15.2 \mathrm{~m} / \mathrm{s}\). Calculate its speed in \(\mathrm{km} / \mathrm{hr}\). (b) The lung capacity of the blue whale is \(5.0 \times 10^{3} \mathrm{~L}\). Convert this volume into gallons. (c) The Statue of Liberty is 151 ft tall. Calculate its height in meters. (d) Bamboo can grow up to \(60.0 \mathrm{~cm} /\) day. Convert this growth rate into inches per hour.

Perform the following conversions: (a) 5.00 days to s, (b) \(0.0550 \mathrm{mi}\) to \(\mathrm{m}\) (c) \(\$ 1.89 /\) gal to dollars per liter, (d) 0.510 in. \(/ \mathrm{ms}\) to \(\mathrm{km} / \mathrm{hr}\), (e) \(22.50 \mathrm{gal} / \mathrm{min}\) to \(\mathrm{L} / \mathrm{s}\) (f) \(0.02500 \mathrm{ft}^{3}\) to \(\mathrm{cm}^{3}\).

(a) How many liters of wine can be held in a wine barrel whose capacity is 31 gal? \((\mathbf{b})\) The recommended adult dose of Elixophyllin \(^{\circ}\), a drug used to treat asthma, is \(6 \mathrm{mg} / \mathrm{kg}\) of body mass. Calculate the dose in milligrams for a \(185-\mathrm{lb}\) person. (c) If an automobile is able to travel \(400 \mathrm{~km}\) on \(47.3 \mathrm{~L}\) of gasoline, what is the gas mileage in miles per gallon? (d) When the coffee is brewed according to directions, a pound of coffee beans yields 50 cups of coffee \((4\) cups \(=1 \mathrm{qt}) .\) How many \(\mathrm{kg}\) of coffee are required to produce 200 cups of coffee?

(a) If an electric car is capable of going \(225 \mathrm{~km}\) on a single charge, how many charges will it need to travel from Seattle, Washington, to San Diego, California, a distance of \(1257 \mathrm{mi}\), assuming that the trip begins with a full charge? (b) If a migrating loon flies at an average speed of \(14 \mathrm{~m} / \mathrm{s}\), what is its average speed in \(\mathrm{mi} / \mathrm{hr} ?\) (c) What is the engine piston displacement in liters of an engine whose displacement is listed as 450 in. \(^{3} ?(\mathbf{d})\) InMarch 1989 , the Exxon Valdezranagroundand spilled 240,000 barrels of crude petroleum off the coast of Alaska. One barrel of petroleum is equal to 42 gal. How many liters of petroleum were spilled?

The density of air at ordinary atmospheric pressure and \(25^{\circ} \mathrm{C}\) is \(1.19 \mathrm{~g} / \mathrm{L}\). What is the mass, in kilograms, of the air in a room that measures \(4.5 \mathrm{~m} \times 5.0 \mathrm{~m} \times 2.5 \mathrm{~m}\) ?

The indoor concentration of ozone above \(300 \mu \mathrm{g} / \mathrm{m}^{3}\) is considered to be unhealthy. What mass of ozone in grams is present in a room measuring \(3.2 \mathrm{~m} \times 2.8 \mathrm{~m} \times 4.1 \mathrm{~m}\) ?

Gold can be hammered into extremely thin sheets called gold leaf. An architect wants to cover a \(30 \mathrm{~m} \times 25 \mathrm{~m}\) ceiling with gold leaf that is twelve-millionths of a centimeter thick. The density of gold is \(19.32 \mathrm{~g} / \mathrm{cm}^{3},\) and gold costs \(\$ 1654\) per troy ounce ( 1 troy ounce \(=31.1034768 \mathrm{~g}\) ). How much will it cost the architect to buy the necessary gold?

A copper refinery produces a copper ingot weighing \(70 \mathrm{~kg}\). If the copper is drawn into wire whose diameter is \(7.50 \mathrm{~mm}\), how many meters of copper can be obtained from the ingot? The density of copper is \(8.94 \mathrm{~g} / \mathrm{cm}^{3}\). (Assume that the wire is a cylinder whose volume \(V=\pi r^{2} h,\) where \(r\) is its radius and \(h\) is its height or length.)

Classify each of the following as a pure substance, a solution, or a heterogeneous mixture: (a) a leaf, (b) a 999 gold bar, (c) stainless steel.

(a) Which is more likely to eventually be shown to be incorrect: an hypothesis or a theory? (b) \(\mathrm{A}(\mathrm{n})\) ___________ reliably predicts the behavior of matter, while a(n) ___________ provides an explanation for that behavior.