Chapter 1

Discuss some ways in which chemistry has changed technology. Give one or more examples of how chemistry has affected another science.

Define the terms experiment and theory. How are theory and experiment related? What is a hypothesis?

Define the terms matter and mass. What is the difference between mass and weight?

State the law of conservation of mass. Describe how you might demonstrate this law.

Characterize gases, liquids, and solids in terms of compressibility and fluidity.

Choose a substance and give several of its physical properties and several of its chemical properties.

A beaker weighed \(50.90 \mathrm{~g}\). To the beaker was added \(5.680 \mathrm{~g}\) of iron pellets and \(53.3 \mathrm{~g}\) of hydrochloric acid. What was the total mass of the beaker and the mixture (before reaction)? Express the answer to the correct number of significant figures.

Give examples of an element, a compound, a heterogeneous mixture, and a homogeneous mixture.

What phases or states of matter are present in a glass of bubbling carbonated beverage that contains ice cubes?

What distinguishes an element from a compound? Can a compound also be an element?

What is meant by the precision of a measurement? How is it indicated?

Distinguish between a measured number and an exact number. Give examples of each.

What is an absolute temperature scale? How are degrees Celsius related to kelvins?

Define density. Describe some uses of density.

Why should units be carried along with numbers in a calculation?

When the quantity \(12.9 \mathrm{~g}\) is added to \(2 \times 10^{-02} \mathrm{~g}\), how many significant figures should be reported in the answer? a. one b. two c. three d. four e. five

You perform an experiment in the lab and determine that there are 36.3 inches in a meter. Using this experimental value, how many millimeters are there in 1.34 feet? a) \(4.43 \times 10^{2} \mathrm{~mm}\) b) \(4.05 \times 10^{2} \mathrm{~mm}\) c) \(44.3 \mathrm{~mm}\) d) \(4.43 \times 10^{5} \mathrm{~mm}\) e) \(4.05 \times 10^{8} \mathrm{~mm}\)

A 75.0 -g sample of a pure liquid, liquid \(A\), with a density of \(3.00 \mathrm{~g} / \mathrm{mL}\) is mixed with a \(50.0-\mathrm{mL}\) sample of a pure liquid, liquid \(\mathrm{B}\), with a density of \(2.00 \mathrm{~g} / \mathrm{mL}\). What is the total volume of the mixture? (Assume there is no reaction upon the mixing of \(\mathrm{A}\) and \(\mathrm{B}\) and volumes are additive. \()\) a \(275 \mathrm{~mL}\) b \(175 \mathrm{~mL}\) c \(125 \mathrm{~mL}\) d \(100 \mathrm{~mL}\) e \(75 \mathrm{mI}\)

1.22 Which of the following represents the smallest mass? a \(23 \mathrm{cg}\) b \(2.3 \times 10^{3} \mu \mathrm{g}\) c \(0.23 \mathrm{mg}\) d \(0.23 \mathrm{~g}\) e \(2.3 \times 10^{-2} \mathrm{~kg}\)

Say you are presented with two beakers, beaker \(\mathrm{A}\) and beaker \(\mathrm{B}\), each containing a white, powdery compound. a) From your initial observations, you suspect that the two beakers contain the same compound. Describe, in general terms, some experiments in a laboratory that you could do to help prove or disprove that the beakers contain the same compound. b) Would it be easier to prove that the compounds are the same or to prove that they are different? Explain your reasoning. c) Which of the experiments that you listed above are the most convincing in determining whether the compounds are the same? Justify your answer. d) A friend states that the best experiment for determining whether the compounds are the same is to see if they both dissolve in water. He proceeds to take \(10.0 \mathrm{~g}\) of each compound and places them in separate beakers, each containing \(100 \mathrm{~mL}\) of water. Both compounds completely dissolve. He then states, "Since the same amount of both substances dissolved in the same volume of water, they must both have the same chemical composition." Is he justified in making this claim? Why or why not?

Part \(\mathrm{I}\) A. Consider three masses that you wish to add together: \(3 \mathrm{~g}, 1.4 \mathrm{~g},\) and \(3.3 \mathrm{~g} .\) These numbers represent measured values. Add the numbers together and report your answer to the correct number of significant figures. B. Now perform the addition in a stepwise fashion in the following manner. Add \(3 \mathrm{~g}\) and \(1.4 \mathrm{~g}\), reporting this sum to the correct number of significant figures. Next, take the number from the first step and add it to \(3.3 \mathrm{~g}\), reporting this sum to the correct number of significant figures. C. Compare your answers from performing the addition in the two distinct ways presented in parts a and \(\mathrm{b}\). Does one of the answers represent a "better" way of reporting the results of the addition? If your answer is yes, explain why your choice is better. D. A student performs the calculation \((5.0 \times 5.143 \mathrm{~g})+\) \(2.80 \mathrm{~g}\) and, being mindful of significant figures, reports an answer of \(29 \mathrm{~g}\). Is this the correct answer? If not, what might this student have done incorrectly? E. Another student performs the calculation \((5 \times 5.143 \mathrm{~g})\) +2.80 and reports an answer of \(29 \mathrm{~g}\). Is this the correct answer? If not, what might this student have done incorrectly? F. Yet another student performs the calculation \((5.00 \times\) \(5.143 \mathrm{~g}\) ) +2.80 and reports an answer of \(28.5 \mathrm{~g}\). Is this the correct answer? If not, what did this student probably do incorrectly? G. Referring to the calculations above, outline a procedure or rule(s) that will always enable you to report answers using the correct number of significant figures. Part \(\mathrm{II}\) A. A student wants to determine the volume of \(27.2 \mathrm{~g}\) of a substance. He looks up the density of the material in a reference book, where it is reported to be \(2.4451 \mathrm{~g} / \mathrm{cm}^{3} .\) He performs the calculation in the following manner: $$27.2 \mathrm{~g} \times 1.0 \mathrm{~cm}^{3} / 2.4 \mathrm{~g}=11.3 \mathrm{~cm}^{3}$$ Is the calculated answer correct? If not, explain why it is not correct. B. Another student performs the calculation in the following manner: $$27.2 \mathrm{~g} \times 1.00 \mathrm{~cm}^{3} / 2.45 \mathrm{~g}=11.1 \mathrm{~cm}^{3}$$ Is this a "better" answer than that of the first student? Is this the "best" answer, or could it be "improved"? Explain. C. Say that you have ten ball bearings, each having a mass of \(1.234 \mathrm{~g}\) and a density of \(3.1569 \mathrm{~g} / \mathrm{cm}^{3} .\) Calculate the volume of these ten ball bearings. In performing the calculation, present your work as unit conversions, and report your answer to the correct number of significant figures. D. Explain how the answer that you calculated in part \(\mathrm{c}\) is the "best" answer to the problem?

A. Sodium metal is partially melted. What are the two phases present? B. A sample of sand is composed of granules of quartz (silicon dioxide) and seashells (calcium carbonate). The sand is mixed with water. What phases are present?

A material is believed to be a compound. Suppose you have several samples of this material obtained from various places around the world. Comment on what you would expect to find upon observing the melting point and color for each sample. What would you expect to find upon determining the elemental composition for each sample?

You need a thermometer that is accurate to \(\pm 5^{\circ} \mathrm{C}\) to conduct some experiments in the temperature range of \(0^{\circ} \mathrm{C}\) to \(100^{\circ} \mathrm{C}\). You find one in your lab drawer that has lost its markings. a. What experiments could you do to make sure your thermometer is suitable for your experiments? b. Assuming that the thermometer works, what procedure could you follow to put a scale on your thermometer that has the desired accuracy?

Say you live in a climate where the temperature ranges from \(-100^{\circ} \mathrm{F}\) to \(20^{\circ} \mathrm{F}\) and you want to define a new temperature scale, YS (YS is the "Your Scale" temperature scale), which defines this range as \(0.0^{\circ} \mathrm{YS}\) to \(100.0^{\circ} \mathrm{YS}\). a) Come up with an equation that would allow you to convert between \({ }^{\circ} \mathrm{F}\) and \({ }^{\circ} \mathrm{YS}\). b) Using your equation, what would be the temperature in \({ }^{\circ} \mathrm{F}\) if it were \(66^{\circ} \mathrm{YS} ?\)

You have two identical boxes with interior dimensions of \(8.0 \mathrm{~cm} \times 8.0 \mathrm{~cm} \times 8.0 \mathrm{~cm}\). You completely fill one of the boxes with wooden spheres that are \(1.6 \mathrm{~cm}\) in diameter. The other box gets filled with wooden cubes that are \(1.6 \mathrm{~cm}\) on each edge. After putting the lid on the filled boxes, you then measure the density of each. Which one is more dense?

Consider the following compounds and their densities. $$ \begin{array}{llll} \text { Substance } & \begin{array}{l} \text { Density } \\ (\mathrm{g} / \mathrm{mL}) \end{array} & \text { Substance } & \begin{array}{l} \text { Density } \\ (\mathrm{glmL}) \end{array} \\ \text { Isopropyl alcohol } & 0.785 & \text { Toluene } & 0.866 \\ n \text { -Butyl alcohol } & 0.810 & \text { Ethylene glycol } & 1.114 \end{array}$$ You create a column of the liquids in a glass cylinder with the most dense material on the bottom layer and the least dense on the top. You do not allow the liquids to mix. A. First you drop a plastic bead that has a density of \(0.24 \mathrm{~g} / \mathrm{cm}^{3}\) into the column. What do you expect to observe? B. Next you drop a different plastic bead that has a volume of \(0.043 \mathrm{~mL}\) and a mass of \(3.92 \times 10^{-2} \mathrm{~g}\) into the column. What would you expect to observe in this case? C. You drop another bead into the column and observe that it makes it all the way to the bottom of the column. What can you conclude about the density of this bead?

A. Which of the following items have a mass of about \(1 \mathrm{~g}\) ? a grain of sand a paper clip a nickel a 5.0 -gallon bucket of water a brick a car B. What is the approximate mass (using SI mass units) of each of the items in part a?

For these questions, be sure to apply the rules for significant figures. A. You are conducting an experiment where you need the volume of a box; you take the length, height, and width measurements and then multiply the values together to find the volume. You report the volume of the box as \(0.310 \mathrm{~m}^{3}\). If two of your measurements were \(0.7120 \mathrm{~m}\) and \(0.52145 \mathrm{~m}\), what was the other measurement? B. If you were to add the two measurements from the first part of the problem to a third length measurement with the reported result of \(1.509 \mathrm{~m}\), what was the value of the third measurement?

A \(15.5 \mathrm{~g}\) sample of sodium carbonate is added to a solution of acetic acid weighing \(19.7 \mathrm{~g}\). The two substances react, releasing carbon dioxide gas to the atmosphere. After reaction, the contents of the reaction vessel weigh \(28.7 \mathrm{~g}\). What is the mass of carbon dioxide given off during the reaction?

Some iron wire weighing \(5.6 \mathrm{~g}\) is placed in a beaker and covered with \(15.0 \mathrm{~g}\) of dilute hydrochloric acid. The acid reacts with the metal and gives off hydrogen gas, which escapes into the surrounding air. After reaction, the contents of the beaker weigh \(20.4 \mathrm{~g} .\) What is the mass of hydrogen gas produced by the reaction?

Zinc metal reacts with yellow crystals of sulfur in a fiery reaction to produce a white powder of zinc sulfide. A chemist determines that \(65.4 \mathrm{~g}\) of zinc reacts with \(32.1 \mathrm{~g}\) of sulfur. How many grams of zinc sulfide could be produced from \(36.9 \mathrm{~g}\) of zinc metal?

Aluminum metal reacts with bromine, a red-brown liquid with a noxious odor. The reaction is vigorous and produces aluminum bromide, a white crystalline substance. A sample of \(27.0 \mathrm{~g}\) of aluminum yields \(266.7 \mathrm{~g}\) of aluminum bromide. How many grams of bromine react with \(18.1 \mathrm{~g}\) of aluminum?

Give the normal state (solid, liquid, or gas) of each of the following. A. sodium hydrogen carbonate (baking soda) B. isopropyl alcohol (rubbing alcohol) C. carbon monoxide D. lead

Give the normal state (solid, liquid, or gas) of each of the following. A. potassium hydrogen tartrate (cream of tartar) B. tungsten C. carbon (graphite) D. mercury

Which of the following are physical changes and which are chemical changes? a. melting of sodium chloride b. pulverizing of rock salt c. burning of sulfur d. dissolving of salt in water

For each of the following, decide whether a physical or a chemical change is involved. a. dissolving of sugar in water b.rusting of iron c. burning of wood d. evaporation of alcohol

A sample of mercury(II) oxide was heated to produce mercury metal and oxygen gas. Then the liquid mercury was cooled to \(-40^{\circ} \mathrm{C},\) where it solidified. A glowing wood splint was thrust into the oxygen, and the splint burst into flame. Identify each physical change and each chemical change.

Solid iodine, contaminated with salt, was heated until the iodine vaporized. The violet vapor of iodine was then cooled to yield the pure solid. Solid iodine and zinc metal powder were mixed and ignited to give a white powder. Identify each physical change and each chemical change.

The following are properties of substances. Decide whether each is a physical property or a chemical property. A. Chlorine gas liquefies at \(-35^{\circ} \mathrm{C}\) under normal pressure. B. Hydrogen burns in chlorine gas. C. Bromine melts at \(-7.2^{\circ} \mathrm{C}\). D. Lithium is a soft, silvery-colored metal. E. Iron rusts in an atmosphere of moist air.

Decide whether each of the following is a physical property or a chemical property of the substance. A. Salt substitute, potassium chloride, dissolves in water. B. Seashells, calcium carbonate, fizz when immersed in vinegar. C. The gas hydrogen sulfide smells like rotten eggs. D. Fine steel wool (Fe) can be burned in air. E. Pure water freezes at \(0^{\circ} \mathrm{C}\).

Iodine is a solid having somewhat lustrous, blue-black crystals. The crystals vaporize readily to a violet-colored gas. Iodine combines with many metals. For example, aluminum combines with iodine to give aluminum iodide. Identify the physical and the chemical properties of iodine that are cited.

Mercury(II) oxide is an orange-red solid with a density of \(11.1 \mathrm{~g} / \mathrm{cm}^{3} .\) It decomposes when heated to give mercury and oxygen. The compound is insoluble in water (does not dissolve in water). Identify the physical and the chemical properties of mercury(II) oxide that are cited.

Consider the following separations of materials. State whether a physical process or a chemical reaction is involved in each separation. a. Sodium chloride is obtained from seawater by evaporation of the water. b. Mercury is obtained by heating the substance mercury(II) oxide; oxygen is also obtained. c. Pure water is obtained from ocean water by evaporating the water, then condensing it. d. Iron is produced from an iron ore that contains the substance iron(III) oxide. e. Gold is obtained from river sand by panning (allowing the heavy metal to settle in flowing water).

All of the following processes involve a separation of either a mixture into substances or a compound into elements. For each, decide whether a physical process or a chemical reaction is required. A. Sodium metal is obtained from the substance sodium chloride. B Iron filings are separated from sand by using a magnet. C Sugar crystals are separated from a sugar syrup by evaporation of water. D Fine crystals of silver chloride are separated from a suspension of the crystals in water. E Copper is produced when zinc metal is placed in a solution of copper(II) sulfate, a compound.

Label each of the following as a substance, a heterogeneous mixture, or a solution. a seawater b sulfur c fluorine d beach sand

Indicate whether each of the following materials is a substance, a heterogeneous mixture, or a solution. a milk b bromine c gasoline d aluminum

Which of the following are pure substances and which are mixtures? For each, list all of the different phases present. a) bromine liquid and its vapor b) paint, containing a liquid solution and a dispersed solid pigment. c) partially molten iron d) baking powder containing sodium hydrogen carbonate and potassium hydrogen tartrate

Which of the following are pure substances and which are mixtures? For each, list all of the different phases present. A a sugar solution with sugar crystals at the bottom B ink containing a liquid solution with fine particles of carbon C a sand containing quartz (silicon dioxide) and calcite (calcium carbonate) D liquid water and steam at \(100^{\circ} \mathrm{C}\)

How many significant figures are there in each of the following measurements? a \(4.0100 \mathrm{mg}\) b \(0.05930 \mathrm{~g}\) c \(6.310 \mathrm{~J}\) d \(0.80090 \mathrm{~m}\) e. \(5.06 \times 10^{-7} \mathrm{~cm}\) f \(2.010 \mathrm{~s}\)