Chapter 1

Use the periodic table to identify these elements: (a) Name an element in Group \(2 \mathrm{~A}\). (b) Name an element in the third period. (c) What element is in the second period in Group \(4 \mathrm{~A}\) ? (d) What element is in the third period in Group \(6 \mathrm{~A}\) ? (e) What halogen is in the fifth period? (f) What alkaline-earth element is in the third period? (g) What noble gas element is in the fourth period? (h) What nonmetal is in Group \(6 \mathrm{~A}\) and the second period? (i) Name a metalloid in the fourth period.

Use the periodic table to identify these elements: (a) Name an element in Group \(2 \mathrm{~B}\). (b) Name an element in the fifth period. (c) What element is in the sixth period in Group \(4 \mathrm{~A} ?\) (d) What element is in the third period in Group \(5 \mathrm{~A}\) ? (e) What alkali metal is in the third period? (f) What noble gas is in the fifth period? (g) Name the element in Group \(6 \mathrm{~A}\) and the fourth period. Is it a metal, nonmetal, or metalloid? (h) Name a metalloid in Group \(5 \mathrm{~A}\).

Which types of compounds contain the majority of the oxygen found in the human body?

(a) In what form are metals found in the body, as atoms or as ions? (b) What are two uses for metals in the human body?

Distinguish between major minerals and trace elements.

Name a mineral that is essential at smaller concentrations but toxic at higher concentrations.

Classify the information in each of these statements as quantitative or qualitative and as relating to a physical or chemical property. (a) A white chemical compound has a mass of \(1.456 \mathrm{~g}\). When placed in water containing a dye, it causes the red color of the dye to fade to colorless. (b) A sample of lithium metal, with a mass of \(0.6 \mathrm{~g}\), was placed in water. The metal reacted with the water to produce the compound lithium hydroxide and the element hydrogen.

Classify the information in each of these statements as quantitative or qualitative and as relating to a physical or chemical property. (a) A liter of water, colored with a purple dye, was passed through a charcoal filter. The charcoal adsorbed the dye, and colorless water came through. Later, the purple dye was removed from the charcoal and retained its color. (b) When a white powder dissolved in a test tube of water, the test tube felt cold. Hydrochloric acid was then added, and a white solid formed.

The label on a bale of mulch indicates a volume of \(1.45 \mathrm{ft}^{3}\). The label also states that the mulch in the bale will cover an area of a garden \(6 \mathrm{ft} \times 6 \mathrm{ft}\) to a depth of 1 in. Account for the discrepancy in the given volumes.

The density of a solution of sulfuric acid is \(1.285 \mathrm{~g} / \mathrm{cm}^{3}\), and it is \(38.08 \%\) acid by mass. Calculate the volume of solution (in \(\mathrm{mL}\) ) that contains \(125 \mathrm{~g}\) of sulfuric acid.

In addition to the metric units of \(\mathrm{nm}\) and \(\mathrm{pm}\), a commonly used unit is the angstrom, where \(1 \AA=1 \times 10^{-10} \mathrm{~m}\). If the distance between a \(\mathrm{Pt}\) atom and an \(\mathrm{N}\) atom in a compound is \(1.97 \AA\), what is the distance in \(\mathrm{nm}\) ? In pm?

The cancer drug cisplatin contains \(65.0 \%\) platinum. You have a \(1.53-\mathrm{g}\) sample of the compound; calculate the mass of platinum it contains.

The density of gaseous helium at \(25^{\circ} \mathrm{C}\) and normal atmospheric pressure is \(1.64 \times 10^{-4} \mathrm{~g} / \mathrm{mL}\). At the same temperature and pressure the density of argon gas is \(1.63 \times 10^{-3} \mathrm{~g} / \mathrm{mL}\). The mass of an atom of argon is almost exactly ten times the mass of an atom of helium. Provide a nanoscale explanation of why the densities differ as they do.

The dimensions of aluminum foil in a box for sale at a supermarket are \(66 \frac{2}{3}\) yards by 12 inches. The mass of the foil is \(0.83 \mathrm{~kg} .\) Calculate the thickness of the foil (in \(\mathrm{cm}\) ). \((1\) in \(=2.54 \mathrm{~cm})\)

Hexane (density \(=0.66 \mathrm{~g} / \mathrm{cm}^{3}\) ), perfluorohexane (density \(=1.669 \mathrm{~g} / \mathrm{cm}^{3}\) ), and water are immiscible liquids; that is, they do not dissolve in one another. You place \(10 \mathrm{~mL}\) of each in a graduated cylinder, along with pieces of high- density polyethylene (HDPE, density \(0.97 \mathrm{~g} / \mathrm{mL}\) ), polyvinyl chloride (PVC, density = \(\left.1.36 \mathrm{~g} / \mathrm{cm}^{3}\right),\) and Teflon (density \(\left.=2.3 \mathrm{~g} / \mathrm{cm}^{3}\right) .\) None of these common plastics dissolves in these liquids. Describe what you expect to see.

Ten of the elements are \(\mathrm{O}, \mathrm{H}, \mathrm{Ar}, \mathrm{Al}, \mathrm{Ca}, \mathrm{Br}, \mathrm{Ge}, \mathrm{K}, \mathrm{Cu}\) and \(P\). Pick the one that best fits each description: (a) an alkali metal; (b) a noble gas; (c) a transition metal; (d) a metalloid; (e) a Group 1 nonmetal; (f) an alkaline-earth metal; \((\mathrm{g})\) a halogen; (h) a nonmetal that is a solid.

Which two elements from this list exhibit the greatest similarity in physical and chemical properties? Explain your choice. \(\mathrm{S}, \mathrm{Ga}, \mathrm{Se}, \mathrm{Ti}\)

Which two elements from this list exhibit the greatest similarity in physical and chemical properties? Explain your choice. \(\mathrm{Mg}, \mathrm{Br}, \mathrm{Si}, \mathrm{Sr}\).

Soap can be made by mixing animal or vegetable fat with a concentrated solution of lye and heating it in a large vat. Suppose that \(3.24 \mathrm{~kg}\) vegetable fat is placed in a large iron vat and then \(50.0 \mathrm{~L}\) water and \(5.0 \mathrm{~kg}\) lye (sodium hydroxide, \(\mathrm{NaOH}\) ) are added. The vat is placed over a fire and heated for two hours, and soap forms. (a) Classify each of the materials identified in the soapmaking process as a substance or a mixture. For each substance, indicate whether it is an element or a compound. For each mixture, indicate whether it is homogeneous or heterogeneous. (b) Assuming that the fat and lye are completely converted into soap, what mass of soap is produced? (c) What physical and chemical processes occur as the soap is made?

The element platinum has a solid-state structure in which platinum atoms are arranged in a cubic shape that repeats throughout the solid. The length of an edge of the cube is \(392 \mathrm{pm}\left(1 \mathrm{pm}=1 \times 10^{-12} \mathrm{~m}\right) .\) Calculate the volume of the cube in cubic meters.

The compound sodium chloride has a solid-state structure in which there is a repeating cubic arrangement of sodium ions and chloride ions. The volume of the cube is \(1.81 \times 10^{-22} \mathrm{~cm}^{3} .\) Calculate the length of an edge of the cube in \(\mathrm{pm}\left(1 \mathrm{pm}=1 \times 10^{-12} \mathrm{~m}\right)\).

You are given a mixture of sand, sugar, and sulfur. Write a detailed description of a procedure that would completely separate each component from this mixture.

You are given a mixture of sand, salt (sodium chloride), and naphthalene, a white solid that is not soluble in water. Write a detailed description of a procedure that would completely separate each component from this mixture.

At \(25^{\circ} \mathrm{C}\) the density of water is \(0.997 \mathrm{~g} / \mathrm{mL},\) whereas the density of ice at \(-10^{\circ} \mathrm{C}\) is \(0.917 \mathrm{~g} / \mathrm{mL}\) (a) If a plastic soft-drink bottle (volume \(=250 \mathrm{~mL}\) ) is completely filled with pure water, capped, and then frozen at \(-10^{\circ} \mathrm{C},\) what volume will the solid occupy? (b) What will the bottle look like when you take it out of the freezer?

When water alone (instead of engine coolant, which contains water and other substances) was used in automobile radiators to cool cast-iron engine blocks, it sometimes happened in winter that the engine block would crack, ruining the engine. Cast iron is not pure iron and is relatively hard and brittle. Explain in your own words how the engine block in a car might crack in cold weather.

Water does not dissolve in bromobenzene. (a) If you pour \(2 \mathrm{~mL}\) water into a test tube that contains \(2 \mathrm{~mL}\) bromobenzene, which liquid will be on top? (b) If you pour \(2 \mathrm{~mL}\) ethanol carefully into the test tube containing bromobenzene and water described in part (a) without shaking or mixing the liquids, what will happen? (c) What will happen if you thoroughly stir the mixture in part (b)?

Water does not mix with either benzene or bromobenzene when it is stirred together with either of them, but benzene and bromobenzene do mix. (a) If you pour \(2 \mathrm{~mL}\) bromobenzene into a test tube, then add \(2 \mathrm{~mL}\) water and stir, what would the test tube look like a few minutes later? (b) Suppose you add \(2 \mathrm{~mL}\) benzene to the test tube in part (a), pouring the benzene carefully down the side of the tube so that the liquids do not mix. Describe the appearance of the test tube now. (c) If the test tube containing all three liquids is thoroughly shaken and then allowed to stand for five minutes, what will the tube look like?

Air mostly consists of diatomic molecules of nitrogen (about \(80 \%\) ) and oxygen (about \(20 \%\) ). Draw a nanoscale picture of a sample of air that contains a total of 10 molecules.

Most pure samples of metals are malleable, which means that if you try to grind up a sample of a metal by pounding on it with a hard object, the pieces of metal change shape but do not break apart. Solid samples of nonmetallic elements, such as sulfur or graphite, are often brittle and break into smaller particles when hit by a hard object. Devise a nanoscale theory about the structures of metals and nonmetals that can account for this difference in macroscale properties.

Rivers add salt (sodium chloride, \(\mathrm{NaCl}\) ) to the oceans of the world at a rate of approximately \(2 \times 10^{16} \mathrm{~g} / \mathrm{yr}\). Assume that Earth is a sphere with a diameter of \(8,000 \mathrm{mi}\), \(67 \%\) of which is covered by oceans to a depth of \(1 \mathrm{mi} .\) The average sodium chloride concentration of the oceans is \(3 \% \mathrm{NaCl}\) by mass and the average density of seawater is \(1.03 \mathrm{~g} / \mathrm{cm}^{3}\). If the rate at which the \(\mathrm{NaCl}\) addition to the oceans has been constant, calculate the approximate age of the oceans. Comment on the reasonableness of your answer given that the age of Earth is \(4.5 \times 10^{9}\) yr.

When \(1.0000 \mathrm{~g}\) silver chloride \((\mathrm{AgCl})\) is all converted to silver iodide \((\mathrm{AgI}), 1.6381 \mathrm{~g} \mathrm{AgI}\) is formed. You know that an atom of iodine has 3.580 times the mass of an atom of chlorine; calculate the mass of silver in each sample. Also calculate the mass of chlorine in the \(\mathrm{AgCl}\) sample and the mass of iodine in the AgI sample.

Rust (an oxide of iron) can be converted to iron metal by reacting it with aluminum metal to form an aluminum oxide. You know that an iron atom has 2.069 times the mass of an aluminum atom. The mass of rust is \(35.48 \mathrm{~g}\) and, when all of the iron has been replaced by aluminum, the mass of the aluminum oxide is \(22.65 \mathrm{~g} .\) Calculate the mass of oxygen in both samples. Also calculate the mass of iron in the rust and the mass of aluminum in the final sample.

Normal respiration rate of humans is \(12-20\) breaths/min. When inhaling, you take in approximately \(500 \mathrm{~mL}\) of air, each milliliter of which contains about \(2.5 \times 10^{19} \mathrm{~mol}-\) ecules. Suppose you delivered a 10 minute speech in a class and, due to the stress you feel during that time, your respiration rate was 20 breaths/min. (a) Calculate the number of air molecules you inhaled during your speech. (b) There are approximately \(1.1 \times 10^{44}\) air molecules in the entire atmosphere. Calculate the fraction of all air molecules in the atmosphere you inhaled during your speech. (c) Now, well after your speech is over, take a breath. Estimate the number of molecules in that breath that also were in the air you inhaled and exhaled during your speech.

In April 2010 the main pipe of the Deepwater Horizon oil-drilling platform burst, spewing crude oil into the Gulf of Mexico. On April \(25,2010,\) the spilled crude oil that reached the surface of the Gulf formed an oil slick \(120 \mathrm{nm}\) thick covering an area of \(1.5 \times 10^{3} \mathrm{~km}^{2}\). Calculate the number of barrels of crude oil in this slick; 1 barrel \(=42\) gal.

You and your lab partner are each given metal cubes that look similar. Your assignment is to make length and mass measurements and use only these data to determine whether the metal is the same in each cube. Your cube is \(1.32 \mathrm{~cm}\) on each edge and has a mass of \(16.23 \mathrm{~g}\). Your partner's cube has a mass of \(24.64 \mathrm{~g}\) and each edge measures \(1.46 \mathrm{~cm}\). Your partner says that the metal is the same in each cube; you don't agree. Refute your partner's conclusion.

Fritz Haber, a German chemist, proposed extracting gold from seawater as a way to pay off Germany's debt, \(\$ 28.8 \times 10^{6}\), after World War I. The value of gold at the time was \(\$ 21.25 /\) troy oz \((1\) troy \(o z=31.103 \mathrm{~g})\). The gold concentration in seawater is \(0.15 \mathrm{mg}\) gold/ton seawater \((1\) ton \(=2000 \mathrm{lb}\) ). Assume the density of seawater is \(1.03 \mathrm{~g} / \mathrm{cm}^{3}\) (a) Calculate the volume (in cubic kilometers) of seawater that would have had to be processed to obtain the required mass of gold. (b) By comparison, an Olympic-sized swimming pool is \(50 \mathrm{~m} \times 25 \mathrm{~m} \times 2.0 \mathrm{~m} .\) Calculate the number of Olympic-sized swimming pools required to hold the volume of seawater needed in part (a).

Prior to 1734 , only 14 elements were known. The rest of the known elements have been discovered across the next nearly three centuries. From \(1805-1825,12\) new elements were discovered. A cluster of six new elements was isolated and identified from \(1895-1905 .\) Beginning in 1940 to the present, 19 new elements have been characterized. During each of these periods of discovery, a single scientific discovery or breakthrough led to the discovery of the new elements. Use the Internet to determine what each of the discoveries was and how it led to the discovery of new elements.

You have some metal shot (small spheres like BBs), and you want to identify the metal. You have a flask that is known to contain exactly \(100.0 \mathrm{~mL}\) when filled with liquid to a mark in the flask's neck. When the flask is filled with water at \(20^{\circ} \mathrm{C}\), the mass of flask and water is \(122.3 \mathrm{~g}\). The water is emptied from the flask and 20 of the small spheres of metal are carefully placed in the flask. The 20 small spheres had a mass of \(42.3 \mathrm{~g}\). The flask is again filled to the mark with water at \(20^{\circ} \mathrm{C}\) and weighed. This time the mass is \(159.9 \mathrm{~g}\). (a) What metal is in the spheres? (Assume that the spheres are all the same and consist of pure metal.) (b) Calculate the volume occupied by 500 spheres.

When volumes of liquids are mixed, the resulting volume is not always equal to the sum of the volume of each liquid. For example, when \(50.0 \mathrm{~mL}\) of ethanol \((\mathrm{d}=\) \(0.789 \mathrm{~g} / \mathrm{mL}\) ) is mixed with \(50.0 \mathrm{~mL}\) of water \((0.998 \mathrm{~g} / \mathrm{mL})\) at \(25^{\circ} \mathrm{C}\), the resulting volume is only \(95.6 \mathrm{~mL}\). Calculate the density of the solution.

Consider a 1.5 in. diameter solid sphere of sterling silver, which is a uniform mixture (an alloy) of \(7.5 \%\) copper and \(92.5 \%\) silver, by mass. The densities of the metals are: copper \(=8.96 \mathrm{~g} / \mathrm{cm}^{3} ;\) silver \(=10.5 \mathrm{~g} / \mathrm{cm}^{3} .\) Calculate the mass of the sphere.

The element zinc reacts with the element sulfur to form a white solid compound, zinc sulfide. When a sample of zinc that weighs \(65.4 \mathrm{~g}\) reacts with sulfur, it is found that the zinc sulfide produced weighs exactly \(97.5 \mathrm{~g}\). (a) Calculate the mass of sulfur in the zinc sulfide. (b) Calculate the mass of zinc sulfide that could be produced from \(20.0 \mathrm{~g}\) zinc.

The element magnesium reacts with the element oxygen to form a white solid compound, magnesium oxide. When a sample of magnesium that weighs \(24.30 \mathrm{~g}\) reacts with oxygen, it is found that the magnesium oxide produced weighs exactly \(40.30 \mathrm{~g}\). (a) Calculate the mass of oxygen in the magnesium oxide. (b) Calculate the mass of magnesium oxide that could be produced from \(40.0 \mathrm{~g}\) magnesium.

A chemist analyzed several portions taken from different parts of a sample that contained only iron, \(\mathrm{Fe},\) and sulfur, S. She reported the results in the table. Could this sample be a compound of iron and sulfur? Explain why or why not. $$ \begin{array}{ccc} \hline \text { Portion } & \text { Total Mass }(g) & \text { Mass of Fe }(g) \\\ \hline 1 & 1.518 & 0.964 \\ 2 & 2.056 & 1.203 \\ 3 & 1.873 & 1.290 \\ \hline \end{array} $$

A chemist analyzed several portions taken from different parts of a sample that contained only selenium, Se, and oxygen, \(\mathrm{O}\). She reported the results in the table. Could this sample be a compound of selenium and oxygen? Explain why or why not. $$ \begin{array}{ccc} \hline \text { Portion } & \text { Total Mass }(g) & \text { Mass of Se }(g) \\\ \hline 1 & 1.518 & 1.08 \\ 2 & 2.056 & 1.46 \\ 3 & 1.873 & 1.33 \\ \hline \end{array} $$

When \(12.6 \mathrm{~g}\) calcium carbonate (the principal component of chalk) is treated with \(63.0 \mathrm{~mL}\) hydrochloric acid (muriatic acid sold in hardware stores; density \(=1.096 \mathrm{~g} / \mathrm{mL}\) ), the calcium carbonate reacts with the acid, goes into solution, and carbon dioxide gas bubbles out of the solution. After all of the carbon dioxide has escaped, the solution weighs \(76.1 \mathrm{~g} .\) Calculate the volume (in liters) of carbon dioxide gas that was produced. (The density of the carbon dioxide gas is \(1.798 \mathrm{~g} / \mathrm{L}\).)