Chapter 1: Matter, Measurements, and Calculations

Chapter 1

Chapter 1: Matter, Measurements, and Calculations

CHAPTER OUTLINE

1.1 What is Matter?

1.2 Physical and Chemical Properties and Changes 1.3 Classifying Matter 1.4 Measurement Units 1.5 The Metric System

1.6 Large and Small Numbers: An Introduction to

Scientific Notation 1.7 Significant Figures

1.8 Using Units in Calculations: An Introduction to

Dimensional Analysis 1.9 Calculating Percentages 1.10 Density and Its Applications

LEARNING OBJECTIVES/ASSESSMENT

When you have completed your study of this chapter, you should be able to:

1.Explain what matter is. (Section 1.1; Exercise 1.2) 2.Explain the difference between the terms physical and chemical as they apply to the properties of matter and changes in matter. (Section 1.2; Exercises 1.8 and 1.10) 3.Classify matter as an element, compound, homogenous mixture, or heterogeneous mixture. (Section 1.3; Exercises 1.16, 1.20, and 1.22) 4.Describe four measurement units used in everyday activities. (Section 1.4; Exercise 1.26)) 5.Convert measurements within the metric system into related units. (Section 1.5; Exercises 1.28 and

1.38))

6.Convert temperatures measured in Fahrenheit to Celsius and vice versa. (Section 1.5; Exercises 1.41 and 1.42) 7.Express numbers using scientific notation. (Section 1.6; Exercises 1.46 and 1.47) 8.Perform calculations with numbers expressed in scientific notation. (Section 1.6; Exercises 1.58 and 1.59) 9.Express measurements and calculations using the correct number of significant figures. (Section 1.7; Exercises 1.62 and 1.64) 10.Use dimensional analysis to solve numerical problems. (Section 1.8; Exercise 1.80) 11.Perform calculations involving percentages. (Section 1.9; Exercise 1.90) 12.Perform calculations involving densities. (Section 1.10; Exercise 1.96)

LECTURE HINTS AND SUGGESTIONS

1.When describing chemistry as the “central science,” explain how everything around us is somehow related to chemistry. Look around the classroom and point out things which are a result of the study of chemistry; such as the plastic materials which make up part of the furniture, the paint on the walls, the clothing that we have on, the paper that we write on, the ink that we write with, and even the biochemical reactions which take place in our bodies which keep us alive.

2.Stress that a pure substance contains only one kind of basic building block or one kind of constituent particle. Every constituent particle in a pure substance is the same. If there are two or more kinds of Fundament als of Chemistry for Today General, Organic, and Bi ochemistry 1e Spencer Seager, Tiffiny Rye-McCurdy, Ryan Yoder (Soluti ons Manual All Chapters, 100% Original Verified, A+ Grade) 1 / 4

Chapter 1 constituent particles present, it is a mixture. Sugar has sugar molecules; water has water molecules; and sugar water has both sugar molecules and water molecules.

3.Emphasize that an important characteristic of a pure substance is a constant composition. Give some simple examples, such as water or salt, which when free of other substances, always have the sam e composition regardless of source. Simple common solutions such as salt water can be used a s examples of mixtures. Also, stress that a mixture may have a varying composition. For example, salt water may contain a very small amount of salt or a lot of salt. Salt water is a mixture. If it is left out in an open dish, the water will evaporate (a physical process) leaving behind the salt.

4.Students sometimes miss the whole point behind significant figures. The most important point to convey is that all measured data have some uncertainty associated with them that is inherent in the measuring device. A simple demonstration is to have students measure the classroom width using a rope knotted at about one-meter intervals, a meter stick and a tape measure. Note: Since the knots in the rope are not numbered, students need to manually count them. Have three students perform th e same counting. The results often differ significantly for a large classroom .

5.Explain that dimensional analysis is just a way to convert between units and it can really save time when solving complex numerical problems. Begin by showing students how equalities can be written as conversion factors (i.e., fractions) and then move to show how multiplying conversion factors together can eliminate unwanted units and solve for the answer in the unit of interest.Emphasize that learning this method may take some time, however, it can be used to solv e quantitative problems presented in not only chemistry but all the natural sciences, and thus it is time well spent learning the method.

6.Providing a handout with commonly used conversion factors and equations is helpful whe n introducing unit conversion and dimensional analysis. The example handout titled Chapter 1: Unit Conversion on the next page could be used as a resource for students to reference as they problem solve. 2 / 4

Chapter 1

CHAPTER 1: UNIT CONVERSION

TABLE 1.2 Common Prefixes of the Metric System

Temperature Scales

TABLE 1.5 Commonly Used Conversion Factors

a A cm 3 is commonly abbreviated “cc.” b A foot-pound is the energy it takes to push with one pound-force (lbf) for a distance of one foot.c A BTU (British thermal unit) is the amount of heat required to increase the temperature of 1 pound of water by 1 °F.

( )°°

5

C F 32

9 = −

( )° °C °

9 F 32 5 = +

°C K 273= −

°K C 273= + 3 / 4

Chapter 1

SOLUTIONS TO ALL END-OF-CHAPTER EXERCISES

What follows are more complete explanations/full solutions to the EOC exercises whose answers are published in shorter form at the end of the textbook

SECTION 1.1 WHAT IS MATTER?

1.1 If a heavy steel ball is suspended by a thin wire and hit from the side with a hammer on the moon, the heavy steel ball will hardly move, just like on earth. This experiment depends only on the mass of the ball and the hammer, not their weights.

1.2 All matter occupies space and has mass. Mass is a measurement of the amount of matter in an object. The mass of an object is constant regardless of where the mass is measured. Weight is a measurement of the gravitational force acting on an object. The weight of an object will change with gravity; therefore, the weight of an object will be different at different altitudes and on different planets.

1.3 To prove to a doubter that air is matter, precisely weigh a deflated balloon, then inflate it and weigh it again. The mass of the inflated balloon will be greater than the mass of the deflated balloon because the air in the inflated balloon has mass. The volume of the air is also clearly evident in the increased size of the balloon.

1.4 The distance you can throw a bowling ball will change more than the distance you can roll a bowling ball on a flat, smooth surface. When throwing a ball, gravity pulls the ball towards the ground and air resistance slows its decent. The gravitational force on the moon is approximately 1/6 th the gravitational force that is present on the earth; therefore, when throwing a ball on the moon, you should be able to throw it further than you can on earth. The moon does not have air resistance. When rolling a ball, friction helps to slow down the ball. If the flat, smooth surface is the same on the earth and the moon, the amount of friction should remain constant.

1.5 a. If you were transported from a deep mine to the top of a tall mountain, your mass would not be changed by the move because mass is independent of gravity.

• If you were transported from a deep mine to the top of a tall mountain, your weight would

decrease because weight depends on gravity and gravity decreases with distance from the earth’s center. A mountaintop is further from the earth’s center than a deep mine; therefore, your weight will be less on the mountaintop.

1.6 The attractive force of gravity for objects near the earth’s surface increases as you get closer to the center of the earth (Exercise 1.5). If the earth bulges at the equator, the people at the equator are further from the center of the earth than people at the North Pole. If two people with the same mass were weighed at the equator and at the North Pole, the person at the equator would weigh less than the person at the North Pole because the gravitational force at the North Pole is stronger than the gravitational force at the equator.

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