Chapter 1

Define science in your own words. List three fields that are science and three fields that are not science.

Compare the uses of the words theory and bypothesis by scientists and by the general public.

Explain how the coach of an athletic team might use scientific methods to enhance the team's performance.

Some scientists think the extinction of the dinosaurs was due to a collision with a large comet or meteor. Is this statement a hypothesis or a theory? Justify your answer.

List three intensive and three extensive properties of air.

Define matter, mass, and weight.

Matter occupies space and has mass. Are the astronauts in a space shuttle composed of matter while they are weightless? Explain your answer.

Give three examples of homogeneous and heterogeneous mixtures.

Do you think it is easier to separate a homogeneous mixture or a heterogeneous mixture, or would both be equally difficult? Explain your answer.

A solution made by dissolving sugar in water is homogeneous because the composition is the same everywhere. But if you could look with very high magnification, you would see locations with water particles and other locations with particles of sugar. How can we say that a sugar solution is homogenous?

I Is the light from an electric bulb an intensive or extensive property?

A Are all alloys homogeneous solutions? Explain your answer.

Explain the differences between substances, compounds, and elements

Football referees mark the ball from its position when the player is down or steps out of bounds. A cumbersome but accurate chain is used to determine whether the ball has advanced 10 yards. Given the high accuracy of the measurement chain, why do many fans and players question the officials when they make these measurements?

Explain the differences between accuracy and precision, and the relationship between the number of significant digits and the precision of a measurement.

Describe a computation in which your calculator does not displav the correct number of significant digits.

Give examples of two numbers, one that is exact (no uncertainty) and one that is not, by using them in a sentence.

If you repeat the same measurement many times, will you always obtain exactly the same result? Why or why not? What factors influence the repeatability of a measurement?

Propose the appropriate SI units and prefixes to express the following values: (a) Diameter of a human hair (b) Distance between New York City and Auckland, New Zealand (c) Mass of water in Lake Michigan (d) Volume of 5 lb table salt (e) Mass of the average house

\- For centuries, a foot was designated as literally a foot the length of the king's foot. What are the disadvantages of such a measurement system? Are there any advantages?

Give an example of a conversion factor that (a) can convert between SI units, and (b) can convert between units of the SI and English system.

A With some simple research, determine what experimental phenomena provide the basis for the standards for six base units. Is there a commonality between any of these phenomena?

Each of the following parts contains an underlined property. Classify the property as intensive or extensive and as chemical or physical. (a) Bromine is a reddish liquid. (b) A ball is a spherical object. (c) Sodium and chlorine react to form table salt. (d) A sample of water has a \(\underline{\text { mass of } 45 \mathrm{~g} \text { . }}\) (e) The density of aluminum is \(\underline{2.70 \mathrm{~g} / \mathrm{cm}^{3} \text { . }}\)

Each of the following parts contains an underlined property. Classify the property as intensive or extensive and as chemical or physical. (a) A lemon is yellow. (b) Sulfuric acid converts sugar to carbon and steam. (c) The sample has a mass of \(1 \mathrm{~kg}\). (d) Sand is insoluble in water. (e) Wood burns in air, forming carbon dioxide and water.

Classify each of the following processes as a chemical change or a physical change. (a) Water boiling (b) Glass breaking (c) Leaves changing color (d) Iron rusting

Classify each of the following processes as a chemical change or a physical change. (a) Tea leaves soaking in warm water (b) A firecracker exploding (c) Magnetization of an iron nail (d) A cake baking

Which of the following processes describe physical changes, and which describe chemical changes? (a) Milk souring (b) Water evaporating (c) The forming of copper wire from a bar of copper (d) An egg frying

Which of the following processes describe physical changes, and which describe chemical changes? (a) A seed growing into a plant (b) Distillation of alcohol (c) Mixing an Alka-Seltzer tablet with water (d) Hammering iron into a horseshoe

Which of the following processes describe physical changes, and which describe chemical changes? (a) Alcohol burns (b) Sugar crystallizes (c) Gas bubbles rise out of a glass of soda (d) A tomato ripens

Which of the following processes describe physical changes, and which describe chemical changes? (a) Meat cooks (b) A candle burns (c) Wood is attached with nails (d) Newspaper yellows with age

In the following description of the element fluorine, identify which of the properties are chemical and which are physical. "Fluorine is a pale-yellow corrosive gas that reacts with practically all substances. Finely divided metals, glass, ceramics, carbon, and even water burn in fluorine with a bright flame. Small amounts of compounds of this element in drinking water and toothpaste prevent dental cavities. The free element has a melting point of \(-219.6^{\circ} \mathrm{C}\) and boils at \(-188.1^{\circ} \mathrm{C}\). Fluorine is one of the few elements that forms compounds with the element xenon."

In the following description of the element iron, identify which of the properties are chemical and which are physical. "Iron is rarely found as the free element in nature. Mostly it is found combined with oxygen in an ore. The metal itself can be obtained by reacting the ore with carbon, producing iron and carbon dioxide. Iron is a silvercolored metal that conducts heat and electricity well. It is one of the most structurally important metals because of its hardness and mechanical strength, and it makes alloys with many other metals. Stainless steel is one useful alloy of iron that does not corrode in the presence of water and

In the following description of the element sodium, identify which of the properties are chemical and which are physical. "Sodium is a soft, silver- colored metal that reacts with water to form sodium hydroxide and hydrogen gas. It is stored under oil because it reacts with air. Sodium melts at \(98^{\circ} \mathrm{C}\), which is relatively low for a metal."

In the following description of the element bromine, identify which of the properties are chemical and which are physical. "Bromine is one of the few elements that is a liquid at room temperature. It is an acrid-smelling substance that reacts readily with most metals. It evaporates easily, so most containers of bromine are filled with visible amounts of red fumes. Most bromine is obtained from sodium bromide, a compound found in salt beds."

Classify each of the following as an element, a compound, or a mixture. Identify mixtures as homogeneous or heterogeneous. (a) Air (b) Sugar (c) Cough syrup (d) Cadmium

Classify each of the following as an element, a compound, or a mixture. Identify mixtures as homogeneous or heterogeneous. (a) Water (b) Window cleaner (c) 14-karat gold (d) Copper

Classify each of the following as an element, a compound, or a mixture. Identify mixtures as homogeneous or heterogeneous. (a) Helium (b) A muddy river (c) Window glass (d) Paint

Classify each of the following as an element, a compound, or a mixture. (a) Gold (b) Milk (c) Sugar (d) Vinaigrette dressing with herbs

Which of the following mixtures is a solution? (a) Air (b) A printed page (c) Milk of magnesia (d) Clear tea

Which of the following mixtures is a solution? (a) Wood (b) Champagne (c) Salt water (d) Cloudv tea

A sample's true mass is \(2.54 \mathrm{~g}\). For each set of measurements, characterize the set as accurate, precise, both, or neither. (a) 2.50,2.55,2.59,2.60 (b) 2.53,2.54,2.54,2.55 (c) 2.49,2.51,2.53,2.63

\- A measurement's true value is \(17.3 \mathrm{~g}\). For each set of measurements, characterize the set as accurate, precise, both, or neither. (a) \(17.2,17.2,17.3,17.3 \mathrm{~g}\) (b) \(16.9,17.3,17.5,17.9 \mathrm{~g}\) (c) \(16.9,17.2,17.9,18.8 \mathrm{~g}\) (d) \(17.8,17.8,17.9,18.0 \mathrm{~g}\)

How many significant figures are in each value? (a) 1.5003 (b) 0.007 (c) 5.70 (d) \(2.00 \times 10^{7}\)

How many significant figures are there in each of the following? (a) \(0.136 \mathrm{~m}\) (b) \(0.0001050 \mathrm{~g}\) (c) \(2.700 \times 10^{3} \mathrm{nm}\) (d) \(6 \times 10^{-4} \mathrm{~L}\) (e) \(56003 \mathrm{~cm}^{3}\)

How many significant figures are in each measurement? (a) \(5 \times 10^{3} \mathrm{~m}\) (b) \(5.0005 \mathrm{~g} / \mathrm{mL}\) (c) \(22.9898 \mathrm{~g}\) (d) \(0.0040 \mathrm{~V}\)

How many significant figures are in each measurement? (a) 3.1416 degrees (b) \(0.00314 \mathrm{~K}\) (c) \(1.0079 \mathrm{~s}\) (d) \(6.022 \times 10^{23}\) particles

Express the measurements to the requested number of significant figures. (a) \(96,485 \mathrm{~J} / \mathrm{C}\) to three significant figures (b) \(2.9979 \mathrm{~g} / \mathrm{cm}^{3}\) to three significant figures (c) \(0.0597 \mathrm{~mL}\) to one significant figure (d) \(6.626 \times 10^{-34} \mathrm{~kg}\) to two significant figures

Express the measurements to the requested number of significant figures. (a) \(0.08205 \mathrm{~kg}\) to three significant figures (b) \(1.00795 \mathrm{~m}\) to three significant figures (c) \(18.9984032 \mathrm{~g}\) to five significant figures (d) \(18.9984032 \mathrm{~g}\) to four significant figures

Perform the indicated calculations, and express the answer to the correct number of significant figures. Use scientific notation where appropriate. (a) \(17.2 \times 12.55\) (b) \(1.4 \times 1.11 / 42.33\) (c) \(18.33 \times 0.0122\) (d) \(25.7-25.25\)

Perform the indicated calculations, and express the answer to the correct number of significant figures. Use scientific notation where appropriate. (a) \(19.5+2.35+0.037\) (b) \(2.00 \times 10^{3}-1.7 \times 10^{1}\) (c) \(15 / 25.69\) (d) \(45.2-37.25\)