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 mi-croscope. 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? [ Section 1.2\(]\)

Consider the two spheres shown here, one made of silver and the other of aluminum.(a) What is the mass of each sphere in \(\mathrm{kg}\) ( b) The force of gravity acting on an object is \(F=m g\) where \(m\) is the mass of an object and \(g\) is the acceleration of gravity \(\left(9.8 \mathrm{m} / \mathrm{s}^{2}\right) .\) How much work do you do on each sphere it you raise it from the floor to a height of 2.2 \(\mathrm{m} ?(\mathrm{c})\) Does the act of lifting the sphere off the ground increase the potential energy of the aluminum sphere by a larger, smaller, or same amount as the silver sphere? (d) If you release the spheres simultaneously, they will have the same velocity when they hit the ground. Will they have the same kinetic energy? If not, which sphere will have more kinetic energy? \([\) Section 1.4\(]\)

Is the separation method used in brewing a cup of coffee best described as distillation, filtration, or chromatography? [Section 1.3\(]\)

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) \(16 \mathrm{nm}^{2},(\mathrm{g})-78^{\circ} \mathrm{C},(\mathbf{h}) 2.56 \mathrm{g} / \mathrm{cm}^{3},(\mathrm{i}) 28 \mathrm{cm}^{3} \cdot[\) Section 1.5\(]\)

Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (a) rice pudding, (b) seawater, (c) magnesium, (d) crushed ice.

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) tomato juice, (c) iodine crystals, (d) sand.

Give the chemical symbol or name for the following elements, as appropriate: (a) sulfur, (b) gold, (c) potassium, (d) chlorine, (e) copper, (f) U, (g) Ni, (h) Na, (i) Al, (i) Si.

Give the chemical symbol or name for each of the following elements, as appropriate: (a) carbon, (b) nitrogen, (c) titanium, \((\mathbf{d})\) zinc, \((\mathbf{e})\) iron, \((\mathbf{f}) \mathrm{P} (\mathrm{g}) \mathrm{Ca},(\mathbf{h}) \mathrm{He},(\mathbf{i}) \mathrm{Pb},(\mathbf{j}) \mathrm{Ag}\)

A solid white substance A is heated strongly in the absence of air. It decomposes to form a new white substance \(B\) and a gas 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 \(\mathrm{A}\) and \(\mathrm{B}\) and gas \(\mathrm{C}\) are elements or compounds?

In the process of attempting to characterize a substance, chemist makes the following observations: The substance i a silvery white, lustrous metal. It melts at \(649^{\circ} \mathrm{C}\) and boils a \(1105^{\circ} \mathrm{C} .\) 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?

Label each of the following as either a physical process or a chemical process: (a) rusting of a metal can, (b) boiling a cup of water, (c) pulverizing an aspirin, (d) digesting a candy bar, (e) exploding of nitroglyerin.

A match is lit and held under a cold piece of metal. The following observations are made: (a) The match burns. (b) The metal gets warmer. (c) Water condenses on the metal. (d) Soot (carbon) isdeposited on the metal. Which of these occurrences are due to physical changes, and which are due to chemical changes?

Which separation method is better suited for separating a solution of sugar and water into pure substances, filtration or distillation?

Two beakers contain clear, colorless liquids. When the contents of the beakers are mixed a white solid is formed. (a) Is this an example of a chemical or a physical change? (b) What would be the most convenient way to separate the newly formed white solid from the liquid mixture- filtration, distillation, or chromatography.

(a) Calculate the kinetic energy, in joules of a 1200 -kg automobile moving at 18 \(\mathrm{m} / \mathrm{s}\) . ( b ) Convert this energy to calories.(c) When the automobile brakes to a stop is the "lost" kinetic energy converted mostly to heat or to some form of potential energy?

(a) A baseball weighs 5.13 oz. What is the kinetic energy, in joules, of this baseball when it is thrown by a major league pitcher at 95.0 \(\mathrm{mi} / \mathrm{h} ?\) (b) By what factor will the kinetic energy change if the speed of the baseball is decreased to 55.0 \(\mathrm{mi} / \mathrm{h} ?\) (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 distance between two oppositely charged particles is increased. (b) Water is pumped from ground level to the reservoir of a water tower 30 \(\mathrm{m}\) above the ground. (c) The bond in a chlorine molecule, \(\mathrm{Cl}_{2},\) is broken to form two chlorine atoms.

Use appropriate metric prefixes to write the following measurements without use of exponents: (a) \(2.3 \times 10^{-10} \mathrm{L}\) ,(b) \(4.7 \times 10^{-6} \mathrm{g},\) (c) \(1.85 \times 10^{-12} \mathrm{m},\) (d) \(16.7 \times 10^{6} \mathrm{s}\) (e) \(15.7 \times 10^{3} \mathrm{g},(\mathrm{f}) 1.34 \times 10^{-3} \mathrm{m},(\mathrm{g}) 1.84 \times 10^{2} \mathrm{cm}\)

Make the following conversions: (a) \(72^{\circ} \mathrm{F}\) to \(^{\circ} \mathrm{C},\) (b) \(216.7^{\circ} \mathrm{C}\) to \(^{\circ} \mathrm{F},(\mathbf{c}) 233^{\circ} \mathrm{C}\) to \(\mathrm{K},(\mathbf{d}) 315 \mathrm{K} \mathrm{to}^{\circ} \mathrm{F},(\mathbf{e}) 2500^{\circ} \mathrm{Fto} \mathrm{K},(\mathbf{f}) 0 \mathrm{K}\) to \(^{\circ} \mathrm{F}\)

(a) The temperature on a warm summer day is \(87^{\circ} \mathrm{F}\) . What is the temperature in \(^{\circ} \mathrm{C} ?\) (b) Many scientific data are reported at \(25^{\circ} \mathrm{C}\) . What is this temperature in kelvins and in degrees Fahrenheit? (c) Suppose that a recipe calls for an oven temperature of \(400^{\circ} \mathrm{F}\) . Convert this temperature to degrees Celsius and to kelvins. (d) Liquid nitrogen boils at 77 \(\mathrm{K}\) . Convert this temperature to degrees Fahrenheit and to degrees 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 usupercritical fluid" that is a much safer dry-cleaning agent than tetrachlorosthvlene, At a certain pressure, the density of super critical \(\mathrm{CO}_{2}\) is 0.469 \(\mathrm{g} / \mathrm{cm}^{3} .\) What is the mass of a 25.0 \(\mathrm{-mL}\) sample of supercritical \(\mathrm{CO}_{2}\) at this pressure?

(a) A cube of osmium metal 1.500 \(\mathrm{cm}\) on a side has a mass of 76.31 \(\mathrm{g}\) at \(25^{\circ} \mathrm{C}\) . What is its density in \(\mathrm{g} / \mathrm{cm}^{3}\) at this temperature? (b) The density of titanium metal is 4.51 \(\mathrm{g} / \mathrm{cm}^{3}\) at \(25^{\circ} \mathrm{C}\) . What mass of titanium displaces 125.0 \(\mathrm{mL}\) of water at \(25^{\circ} \mathrm{C} ?\) (c) The density of benzene at \(15^{\circ} \mathrm{C}\) is 0.8787 \(\mathrm{g} / \mathrm{mL}\) . Calculate the mass of 0.1500 L of benzene at this temperature.

(a) To identify a liquid substance, a student determined its density. Using a graduated cylinder, she measured out a 45 -mL. sample of the substance. She then measured the mass of the sample, finding that it weighed 38.5 \(\mathrm{g}\) . She knew that the substance had to be either isopropylalcohol (density 0.785 \(\mathrm{g} / \mathrm{mL}\) )or toluene (density 0.866 \(\mathrm{g} / \mathrm{mL} ) .\) What are the calculated density and the probable identity of the substance? (b) An experiment requires 45.0 \(\mathrm{g}\) of ethylene glycol, a liquid whose density is 1.114 \(\mathrm{g} / \mathrm{mL}\) . Rather than weigh the sample on a balance, a chemist chooses to dispense the liquid using a graduated cylin-der. What volume of the liquid should he use? (c) Is a graduated cylinder such as that shown in Figure 1.21 likely to afford the accuracy of measurement needed? (d) A cubic piece of metal measures 5.00 \(\mathrm{cm}\) on each edge. If the metal is nickel, whose density is \(8.90 \mathrm{g} / \mathrm{cm}^{3},\) what is the mass of the cube?

(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 \(\mathrm{g} .\) A chemistry handbook lists the density of benzene at \(15^{\circ} \mathrm{C}\) as 0.8787 \(\mathrm{g} / \mathrm{mL} .\) Is the calculated density 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.)

In the year \(2013,\) an estimated amount of 36 billion metrictons ( 1 metric ton \(=1000 \mathrm{kg}\) ) of carbon dioxide \(\left(\mathrm{CO}_{2}\right)\) was emitted worldwide due to fossil fuel combustion and cement production. Express this mass of \(\mathrm{CO}_{2}\) in grams without exponential notation, using an appropriate metric prefix.

Silicon for computer chips is grown in large cylinders called aboules" 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 -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.)

A watt is a measure of power (the rate of energy change) equal to 1 \(\mathrm{Js.}(\mathbf{a})\) 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?

What is the number of significant figures in each of the following measured quantities? (a) \(601 \mathrm{kg},\) (b) 0.054 \(\mathrm{s}\) ,(c) \(6.3050 \mathrm{cm},(\mathbf{d}) 0.0105 \mathrm{L},(\mathbf{e}) 7.0500 \times 10^{-3} \mathrm{m}^{3},(\mathbf{f}) 400 \mathrm{g}\)

Indicate the number of significant figures in each of the following measured quantities: (a) \(3.774 \mathrm{km},\) (b) 205 \(\mathrm{m}^{2}\) , (c) \(1.700 \mathrm{cm},(\mathbf{d}) 350.00 \mathrm{K},(\mathbf{e}) 307.080 \mathrm{g},(\mathbf{f}) 1.3 \times 10^{3} \mathrm{m} / \mathrm{s}\) .

Round each of the following numbers to four significant figures and express the result in standard exponential notation: (a) \(102.53070,\) (b) \(656.980,\) (c) 0.008543210 ,(d) \(0.000257870 (\mathbf{e})-0.0357202\)

(a) The diameter of Earth at the equator is 7926.381 \(\mathrm{mi}\) . 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 figures. $$ \begin{array}{ll}{\text { (a) } 14.3505+2.65} & {\text { (b) } 952.7-140.7389} \\\ {\text { (c) }\left(3.29 \times 10^{4}\right)(0.2501)} & {\text { (d) } 0.0588 / 0.677}\end{array} $$

Carry out the following operations and express the answer with the appropriate number of significant figures. $$ \begin{array}{l}{\text { (a) } 320.5-(6104.5 / 2.3)} \\ {\text { (b) }\left[\left(285.3 \times 10^{5}\right)-\left(1.200 \times 10^{3}\right)\right] \times 2.8954} \\ {\text { (c) }(0.0045 \times 20,000.0)+(2813 \times 12)} \\ {\text { (a) } 863 \times[1255-(3.45 \times 108)]}\end{array} $$

Using your knowledge of metric units, English units, and the information on the back inside cover, write down the con- version factors needed to convert (a) mm to nm, (b) mg to kg, (c) km to ft, (d) in. \(^{3}\) to \(\mathrm{cm}^{3} .\)

Using your knowledge of metric units, English units, and the information on the back inside cover, write down the conversion factors needed to convert (a) \mum to mm, (b) ms to ns, (c) mi to km, (d) \(\mathrm{ft}^{3}\) to \(\mathrm{L}\) .

(a) The speed of light in a vacuum is \(2.998 \times 10^{8} \mathrm{m} / \mathrm{s}\) . Calculate its speed in miles per hour. (b) The Sears Tower in Chicago is 1454 ft tall. Calculate its height in meters. (c) The Vehicle Assembly Building at the Kennedy Space Center in Florida has a volume of \(3,666,500 \mathrm{m}^{3} .\) Convert this volume to liters and express the result in standard exponential no- tation. (d) An individual suffering from a high cholesterol level in her blood has 242 mg of cholesterol per 100 \(\mathrm{mL}\) of blood. If the total blood volume of the individual is 5.2 \(\mathrm{L}\) , how many grams of total blood cholesterol does the individual's body contain?

Perform the following conversions: (a) 5.00 days to s, (b) 0.0550 \(\mathrm{mi}\) to \(\mathrm{m},(\mathbf{c}) \$ 1.89 / \mathrm{gal}\) 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? (b) The recommended adult dose of Elixophyllin', a drug used to treat asthma, is 6 \(\mathrm{mg} / \mathrm{kg}\) of body mass. Calculate the dose in milligrams for a 185 -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 \(=1\) qt). How many kg of coffee are required to produce 200 cups of coffee?

Gold can be hammered into extremely thin sheets called gold leaf. An architect wants to cover a 100 \(\mathrm{ft} \times 82\) ft ceiling with gold leaf that is five-millionths of an inch 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 150 \(\mathrm{lb}\) . If the copper is drawn into wire whose diameter is 7.50 \(\mathrm{mm}\) , how many feet 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 ris 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 gold ingot, (b) a cup of coffee, (c) a wood plank.

A sample of ascorbic acid (vitamin \(\mathrm{C} )\) is synthesized in the laboratory. It contains 1.50 \(\mathrm{g}\) of carbon and 2.00 \(\mathrm{g}\) of oxygen. Another sample of ascorbic acid isolated from citrus fruits contains 6.35 \(\mathrm{g}\) of carbon. According to the law of constant composition, how many grams of oxygen does it contain?

Ethyl chloride is sold as a liquid (see photo) under pressure for use as a local skin anesthetic. Ethyl chloride boils at \(12^{\circ \circ} \mathrm{C}\) at atmospheric pressure. When the liquid is sprayed onto the skin, it boils off, cooling and numbing the skin as it vaporizes. (a) What changes of state are involved in this use of ethyl chloride? (b) What is the boiling point of ethyl chlo- ride in degrees Fahrenheit? (c) The bottle shown contains 103.5 \(\mathrm{mL}\) of ethyl chloride. The density of ethyl chloride at \(25^{\circ} \mathrm{C}\) is 0.765 \(\mathrm{g} / \mathrm{cm}^{3} .\) What is the mass of ethyl chloride in the bottle?

Two students determine the percentage of lead in a sample as a laboratory exercise. The true percentage is 22.52\(\%\) . The students' results for three determinations are as follows: $$\begin{array}{l}{\text { (1) } 22.52,22.48,22.54} \\ {\text { (2) } 22.64,22.58,22.62}\end{array}$$ (a) Calculate the average percentage for each set of data and state which set is the more accurate based on the average. (b) Precision can be judged by examining the average of the deviations from the average value for that data set. (Calculate the average value for each data set; then calculate the average value of the absolute deviations of each measurement from the average.) Which set is more precise?

Is the use of significant figures in each of the following statements appropriate? (a) The 2005 circulation of National Geo graphic was \(7,812,564\) . (b) On July 1, 2005, the population of Cook County, Illinois, was \(5,303,683 .(\mathbf{c})\) In the United States, 0.621\(\%\) of the population has the surname Brown. (\boldsymbol{d} ) ~ Y o u ~ c a l c u l a t e ~ y o u r ~ g r a d e ~ p o i n t ~ a v e r a g e ~ t o ~ b e ~ 3.87562

What type of quantity (for example, length, volume, density) do the following units indicate? (a) \(\mathrm{mL},(\mathbf{b}) \mathrm{cm}^{2}\) ,\((\mathbf{c}) \mathrm{mm}^{3},(\mathbf{d}) \mathrm{mg} / \mathrm{L},(\mathbf{e}) \mathrm{ps},(\mathbf{f}) \mathrm{nm},(\mathrm{g}) \mathrm{K}\)

Give the derived SI units for each of the following quantities in base Sl units: $$\begin{array}{l}{\text { (a) acceleration }=\text { distance } / \text { time }^{2}} \\ {\text { (b) force }=\text { mass } \times \text { acceleration }} \\ {\text { (c) work }=\text { force } \times \text { distance }} \\ {\text { (d) pressure }=\text { force/area }}\end{array}$$$$ \begin{array}{l}{\text { (e) power }=\text { work/time }} \\ {\text { (f) velocity }=\text { distance } / \text { time }} \\ {\text { (g) energy }=\text { mass } \times \text { (velocity) }^{2}}\end{array} $$

The distance from Earth to the Moon is approximately \(240,000 \mathrm{mi.}\) (a) What is this distance in meters? (b) The peregrine falcon has been measured as traveling up to 350 \(\mathrm{km} /\) hr in a dive. If this falcon could fly to the Moon at this speed, how many seconds would it take? (c) The speed of light is \(3.00 \times 10^{8} \mathrm{m} / \mathrm{s} .\) How long does it take for light to travel from Earth to the Moon and back again? (\boldsymbol{d} ) ~ E a r t h ~ t r a v e l s ~ a r o u n d ~the Sun at an average speed of 29.783 \(\mathrm{km} / \mathrm{s} .\) Convert this speed to miles per hour.

Which of the following would you characterize as a pure or nearly pure substance? (a) baking powder; (b) lemon juice; (c) propane gas, used in outdoor gas grills; (d) aluminum foil; (e) ibuprofen; (f) bourbon whiskey; (g) helium gas; (h) clear water pumped from a deep aquifer.