Chapter 1

Give the name of each of the following elements: (a) \(\mathbf{C}\) (b) \(\mathrm{K}\) (c) \(\mathrm{Cl}\) (d) \(\mathbf{P}\) (e) \(\mathrm{Mg}\) (f) \(\mathrm{Ni}\)

Give the name of each of the following elements: (a) Mn (b) Cu (c) Na (d) Br (e) Xe (f) Fe

Give the symbol for each of the following elements: (a) barium (b) titanium (c) chromium (d) lead (e) arsenic (f) zinc

Give the symbol for each of the following elements: (a) silver (b) aluminum (c) plutonium (d) tin (e) technetium (f) krypton

In each of the following pairs, decide which is an element and which is a compound. (a) Na or NaCl (b) sugar or carbon (c) gold or gold chloride

In each of the following pairs, decide which is an element and which is a compound. (a) \(\mathrm{Pt}\left(\mathrm{NH}_{3}\right)_{2} \mathrm{Cl}_{2}\) or \(\mathrm{Pt}\) (b) copper or copper(II) oxide (c) silicon or sand

In each case, decide if the underlined property is a physical or chemical property. (a) The color of elemental bromine is orange-red. (b) Iron turns to rust in the presence of air and water. (c) Hydrogen can explode when ignited in air (Figure \(1.16)\) (d) The density of titanium metal is \(4.5 \mathrm{g} / \mathrm{cm}^{3} .\) (e) Tin metal melts at \(505 \mathrm{K}\) (f) Chlorophyll, a plant pigment, is green.

In each case, decide if the change is a chemical or physical change. (a) A cup of household bleach changes the color of your favorite T-shirt from purple to pink. (b) Water vapor in your exhaled breath condenses in the air on a cold day. (c) Plants use carbon dioxide from the air to make sugar. (d) Butter melts when placed in the sun.

Which part of the description of a compound or element refers to its physical properties and which to its chemical properties? (a) The colorless liquid ethanol burns in air. (b) The shiny metal aluminum reacts readily with orange-red bromine.

Which part of the description of a compound or element refers to its physical properties and which to its chemical properties? (a) Calcium carbonate is a white solid with a density of \(2.71 \mathrm{g} / \mathrm{cm}^{3} .\) It reacts readily with an acid to produce gaseous carbon dioxide. (b) Gray, powdered zinc metal reacts with purple iodine to give a white compound.

A solar panel is pictured in the photo. When light shines on the panel, it generates an electric current that can be used to recharge the batteries in an electric car. What types of energy are involved in this setup?

Determine which of the following represent potential energy and which represent kinetic energy. (a) thermal energy (b) gravitational energy (c) chemical energy (d) electrostatic energy

Determine whether kinetic energy is being converted to potential energy, or vice versa, in the following processes. (a) Water cascades downward in a waterfall. (b) Electrolysis of water produces \(\mathrm{H}_{2}\) and \(\mathrm{O}_{2}\). (c) An electric current is generated by a chemical reaction in a battery. (d) Water boils when heated on a gas stove.

A piece of turquoise is a blue-green solid; it has a density of \(2.65 \mathrm{g} / \mathrm{cm}^{3}\) and a mass of \(2.5 \mathrm{g}.\) (a) Which of these observations are qualitative and which are quantitative? (b) Which of the observations are extensive and which are intensive? (c) What is the volume of the piece of turquoise?

Iron pyrite (fool's gold, Figure 1.11 ) has a shiny golden metallic appearance. Crystals are often in the form of perfect cubes. A cube \(0.40 \mathrm{cm}\) on each side has a mass of \(0.064 \mathrm{g}\) (a) Which of these observations are qualitative and which are quantitative? (b) Which of the observations are extensive and which are intensive? (c) What is the density of the sample of iron pyrite?

Which observations below describe chemical properties? (a) Sugar is soluble in water. (b) Water boils at \(100^{\circ} \mathrm{C}\) (c) Ultraviolet light converts \(\mathrm{O}_{3}\) (ozone) to \(\mathrm{O}_{2}\) (oxygen). (d) Ice is less dense than water.

Which observations below describe chemical properties? (a) Sodium metal reacts violently with water. (b) \(\mathrm{CO}_{2}\) does not support combustion. (c) Chlorine is a green gas. (d) Heat is required to melt ice.

Small chips of iron are mixed with sand (see photo). Is this a homogeneous or heterogeneous mixture? Suggest a way to separate the iron from the sand. (Check your book to see image)

You have a solution of NaCl dissolved in water. Describe a method by which these two compounds could be separated.

Identify the following as either physical changes or chemical changes. (a) Dry ice (solid \(\mathrm{CO}_{2}\)) sublimes (converts directly from solid to gas phase). (b) Mercury's density decreases as the temperature increases. (c) Energy is given off as heat when natural gas (mostly methane, \(\mathrm{CH}_{4}\)) burns. (d) NaCl dissolves in water.

Identify the following as either physical changes or chemical changes. (a) The desalination of sea water (separation of pure water from dissolved salts). (b) The formation of \(\mathrm{SO}_{2}\) (an air pollutant) when coal containing sulfur is burned. (c) Silver tarnishes. (d) Iron is heated to red heat.

Carbon tetrachloride, \(\mathrm{CCl}_{4},\) a common liquid compound, has a density of \(1.58 \mathrm{g} / \mathrm{cm}^{3} .\) If you place a piece of a plastic soda bottle \(\left(d=1.37 \mathrm{g} / \mathrm{cm}^{3}\right)\) and a piece of aluminum \(\left(d=2.70 \mathrm{g} / \mathrm{cm}^{3}\right)\) in liquid \(\mathrm{CCl}_{4},\) will the plastic and aluminum float or sink?

Categorize each of the following as an element, a compound, or a mixture. (a) sterling silver (b) carbonated mineral water (c) tungsten (d) aspirin

Categorize each of the following as an element, a compound, or a mixture. (a) air (c) brass (b) fluorite (d) 18 -carat gold

Make a drawing, based on the kinetic-molecular theory and the ideas about atoms and molecules presented in this chapter, of the arrangement of particles in each of the cases listed here. For each case, draw 10 particles of each substance. It is acceptable for your diagram to be two dimensional. Represent each atom as a circle, and distinguish each different kind of atom by shading. (a) a sample of solid iron (which consists of iron atoms) (b) a sample of liquid water (which consists of \(\mathrm{H}_{2} \mathrm{O}\) molecules) (c) a sample of water vapor

A Make a drawing, based on the kinetic-molecular theory and the ideas about atoms and molecules presented in this chapter, of the arrangement of particles in each of the cases listed here. For each case, draw 10 particles of each substance. It is acceptable for your diagram to be two dimensional. Represent each atom as a circle, and distinguish each different kind of atom by shading. (a) a homogeneous mixture of water vapor and helium gas (which consists of helium atoms) (b) a heterogeneous mixture consisting of liquid water and solid aluminum; show a region of the sample that includes both substances (c) a sample of brass (which is a homogeneous solid mixture of copper and zinc)

Hexane \(\left(\mathrm{C}_{6} \mathrm{H}_{14}, \text { density }=0.766 \mathrm{g} / \mathrm{cm}^{3}\right),\) perfluorohexane \(\left(\mathrm{C}_{6} \mathrm{F}_{14}, \text { density }=1.669 \mathrm{g} / \mathrm{cm}^{3}\right),\) 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 \(=0.97 \mathrm{g} / \mathrm{cm}^{3}\) ), polyvinyl chloride (PVC, \(\left.\text { density }\left.=1.36 \mathrm{g} / \mathrm{cm}^{3}\right), \text { and Teflon (density }=2.3 \mathrm{g} / \mathrm{cm}^{3}\right)\) None of these common plastics dissolves in these liquids. Describe what you expect to see.

You have a sample of a white crystalline substance from your kitchen. You know that it is either salt or sugar. Although you could decide by taste, suggest another property that you could use to decide. (Hint: You may use the World Wide Web or a handbook of chemistry in the library to find some information.)

You can figure out whether a substance floats or sinks if you know its density and the density of the liquid. In which of the liquids listed below will high- density polyethylene (HDPE) float? (HDPE, a common plastic, has a density of \(0.97 \mathrm{g} / \mathrm{cm}^{3} .\) It does not dissolve in any of these liquids.) $$\begin{array}{lcl}\text { Substance } & \text { Density }\left(\mathrm{g} / \mathrm{cm}^{3}\right) & \text { Properties,Uses } \\\\\hline \text { Ethylene } & 1.1088 & \text { Toxic; major component of } \\\\\text { glycol } & & \text { automobile antifreeze } \\\\\text { Water } & 0.9997 & \\\\\text { Ethanol } & 0.7893 & \text { Alcohol in alcoholic beverages } \\\\\text { Methanol } & 0.7914 & \text { Toxic; gasoline additive to } \\\& & \text { prevent gas line freezing } \\\\\text { Acetic acid } & 1.0492 & \text { Component of vinegar } \\\\\text { Glycerol } & 1.2613 & \text { Solvent used in home care } \\\& & \text { products } \\\\\hline\end{array}$$

Milk in a glass bottle was placed in the freezing compartment of a refrigerator overnight. By morning, a column of frozen milk emerged from the bottle. Explain this observation. (Check your book to see image)

You are given a sample of a silvery metal. What information could you use to prove the metal is silver?

Describe an experimental method that can be used to determine the density of an irregularly shaped piece of metal.

Diabetes can alter the density of urine, so urine density can be used as a diagnostic tool. Diabetics can excrete too much sugar or excrete too much water. What do you predict will happen to the density of urine under each of these conditions? (Hint: Water containing dissolved sugar is more dense than pure water.)

Suggest a way to determine if the colorless liquid in a beaker is water. How could you discover if there is salt dissolved in the water?

Three liquids of different densities are mixed. Because they are not miscible (do not form a homogeneous solution with one another), they form discrete layers, one on top of the other. Sketch the result of mixing carbon tetrachloride \(\left(\mathrm{CCl}_{4}, d=1.58 \mathrm{g} / \mathrm{cm}^{3}\right),\) mercury \(\left(d=13.546 \mathrm{g} / \mathrm{cm}^{3}\right),\) and water \(\left(d=1.00 \mathrm{g} / \mathrm{cm}^{3}\right).\)

Four balloons are each filled with a different gas, each having a different density: $$\text { helium, } d=0.164 \mathrm{g} / \mathrm{L} \quad \text { neon, } d=0.825 \mathrm{g} / \mathrm{L}$$ $$\begin{aligned}&\text { argon, } d=1.633 \mathrm{g} / \mathrm{L}&\text { krypton, } d=4.425 \mathrm{g} / \mathrm{L}\end{aligned}$$ If the density of dry air is \(1.12 \mathrm{g} / \mathrm{L},\) which balloon or balloons float in air?

A copper-colored metal is found to conduct an electric current. Can you say with certainty that it is copper? Why or why not? Suggest additional information that could provide unequivocal confirmation that it is copper.

You want to determine the density of a compound but have only a tiny crystal, and it would be difficult to measure mass and volume accurately. There is another way to determine density, however, called the flotation method. If you placed the crystal in a liquid whose density is precisely that of the substance, it would be suspended in the liquid, neither sinking to the bottom of the beaker nor floating to the surface. However, for such an experiment you would need to have a liquid with the precise density of the crystal. You can accomplish this by mixing two liquids of different densities to create a liquid having the desired density. (a) Consider the following: you mix \(10.0 \mathrm{mL}\) of \(\mathrm{CHCl}_{3}\) \((d=1.492 \mathrm{g} / \mathrm{mL})\) and \(5.0 \mathrm{mL}\) of \(\mathrm{CHBr}_{3}(d=2.890\) \(\mathrm{g} / \mathrm{mL}),\) giving \(15.0 \mathrm{mL}\) of solution. What is the density of this mixture? (b) Suppose now that you wanted to determine the density of a small yellow crystal to confirm that it is sulfur. From the literature, you know that sulfur has a density of \(2.07 \mathrm{g} / \mathrm{cm}^{3} .\) How would you prepare \(20.0 \mathrm{mL}\) of the liquid mixture having that density from pure samples of \(\mathrm{CHCl}_{3}\) and \(\mathrm{CHBr}_{3} ? \quad\) (Note: \(1 \mathrm{mL}=1 \mathrm{cm}^{3}\).)