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Chemistry 140/145

Chemistry 140/145. TCHS Charles Lee-Instructor Hopkinsville Community College. Chapter 1: Matter, Measurements, and Calculations. 1.1 What Is Matter ? When you have completed your study of this chapter, you should be able to:. LEARNING OBJECTIVES/ASSESSMENT.

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Chemistry 140/145

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  1. Chemistry 140/145 TCHS Charles Lee-Instructor Hopkinsville Community College

  2. Chapter 1: Matter, Measurements, and Calculations • 1.1 What Is Matter? • When you have completed your study of this chapter, you should be able to:

  3. LEARNING OBJECTIVES/ASSESSMENT • 1. Explain what matter is. (Section 1.1; Exercise 1.2) • 2. Explain differences between the terms physical and chemical as applied to: • a. Properties of matter (Section 1.2; Exercises 1.10 b & c) • b. Changes in matter (Section 1.2; Exercises 1.8 a & b) • 3. Describe matter in terms of the accepted scientific model. (Section 1.3; Exercise 1.12) • 4. On the basis of observation or information given to you, classify matter into the correct category of each of the following pairs: • a. Heterogeneous or homogeneous (Section 1.4; Exercise 1.22) • b. Solution or pure substance (Section 1.4; Exercise 1.24) • c. Element or compound (Section 1.4; Exercise 1.18)

  4. LEARNING OBJECTIVES/ASSESSMENT • 5. Recognize the use of measurement units in everyday activities. (Section 1.5; Exercise 1.28) • 6. Recognize units of the metric system, and convert measurements done using the metric system into related units. (Section 1.6; Exercises 1.30 and 1.40) • 7. Express numbers using scientific notation, and do calculations with numbers expressed in scientific notation. (Section 1.7; Exercises 1.48 and 1.60) • 8. Express the results of measurements and calculations using the correct number of significant figures. • (Section 1.8; Exercises 1.64 and 1.66) • 9. Use the factor‐unit method to solve numerical problems. (Section 1.9; Exercise 1.82) • 10. Do calculations involving percentages. (Section 1.10; Exercise 1.92) • 11. Do calculations involving densities. (Section 1.11; Exercise 1.98)

  5. Chapter 1: Matter, Measurements, and Calculations • CHAPTER OUTLINE • 1.1 What Is Matter? • 1.2 Properties and Changes • 1.3 A Model of Matter • 1.4 Classifying Matter • 1.5 Measurement Units • 1.6 The Metric System • 1.7 Large and Small Numbers • 1.8 Significant Figures • 1.9 Using Units in Calculations • 1.10 Calculating Percentages • 1.11 Density

  6. 1.1 Explain what matter is. • matter - anything that occupies space and has mass • mass - the amount of matter(atoms) a body possesses • weight - a measure of the earth’s gravitational attraction on matter

  7. Physical Properties - those which can be determined without a change in identity Examples length mass color Chemical Properties - ability of a substance to undergo a change in identity Examples iron rusts milk sours silver tarnishes 1.2 Properties ofmatter. Explain differences between the terms physical and chemical as applied to:

  8. 1.3 Describe matter in terms of the accepted scientific model. • liquid - definite volume, indefinite shape • solid - definite shape and volume • gas - neither definite shape nor definite volume

  9. 1.4 On the basis of observation or information given to you, classify matter into the correct category of each of the following pairs: • a. Heterogeneous or homogeneous • b. Solution or pure substance • c. Element or compound

  10. Classification of Matter

  11. 1.5 Recognize the use of measurement units in everyday activities. • Measurements are essential to ensuring fairness in sports. • SI measurements are used on everything from keeping accurate event times, the correct pressure of sports balls, and measuring competition distances. • The most frequent measurements made in the home are those used for cooking and baking. • Metric "cup and spoon" measures are only slightly larger than, and can often be used interchangeably with, the customary "cup and spoon" measures.

  12. Metric Chocolate Chip Cookies • Ingredients: • 550 mL unsifted flour • 5 mL baking soda • 5 mL salt • 250 mL butter or margarine, softened • 175 mL granulated sugar • 175 mL firmly packed brown sugar • 5 mL vanilla extract • Preheat the oven to 190 ºC. In small bowl, combine flour, baking soda, and salt; set aside. In large bowl, combine butter, sugar, brown sugar, and vanilla; beat until creamy. Beat in eggs. Gradually add flour mixture; mix well. Stir in chocolate chips and nuts. Using 5 mL measure, drop by rounded measures into ungreased cookie sheet. Bake 8 to 10 minutes.Makes 100 (5 cm) cookies

  13. 1.6 Recognize units of the metric system, and convert measurements done using the metric system intorelated units. • SI(International System) Fundamental Units • Quantity UnitSymbol • length meterm • mass kilogramKg • time second s • temperature KelvinK • amount of matter mole mol

  14. Derived Units • derived unit - a unit obtained by combinations of fundamental units • Example - volume (cm3) • V = l X w X h • V(cm3) = (cm) X (cm) X (cm) • 1cm3 = 1mL • How many liters in one cubic meter?

  15. 1.7 Express numbers using scientific notation, and do calculations with numbers expressed in scientific notation. • scientific notation - an expression of numbers as powers of 10 • Express 93,000,000 in scientific notation • 93,000,000 • Express 0.000 000 000 189 in scientific notation. • 0.000 000 000 189

  16. 1.8 Express the results of measurements and calculations using the correct number of significant figures. • The following rules are used to determine the number of significant digits. • 1. Nonzero digits are always significant. • 2. All final zeros after the decimal point are significant. • 3. Zeros between two other significant digits are always significant. • 4. Zeros used solely for spacing the decimal point are not significant.

  17. How many sigdigs in the following? • 1. 0.0003100500 • 2. 1,000,000,000 • 3. 1.00004 • 4. 0.00000001000 • 5. 6.404 X 106

  18. Operations With Significant Digits • Addition and Subtraction • The answer should be rounded off so that the final digit is in the same place as the leftmost uncertain digit. • Example • 34.9 • +4.56 • 39.46.......the correct answer is 39.5

  19. Operations With Significant Digits • Multiplication and Division • The answer should be rounded off to the same number of significant digits as the measurement with the least number of significant digits. • Example • 2.34 X 6.5 = 15.21 • the correct answer is 15

  20. Perform the indicated operations using sidigs. • 1. 23.67 + 4.5 = • 2. 4.5 – 3.888 = • 3. (3.5 X 102) – (2.3 X 102) • 4. (3.5 X 102) X (2.3 X 102) • 5. (3.5 X 102) ÷ (2.3 X 102)

  21. 9. Use the factor‐unit method to solve numerical problems. • 1. How many seconds in 1 year, 365 days? • 2. Dr. Michael prescribes 300 mg a day of medicine to a patent. Each pill has 15 mg of medicine. How many pills will the patient need for 7 days? • 3. A solution contains 5 grams of glucose per 100 milliliters. Each mole of glucose weighs 180 grams. How many moles are there in 200 milliliters of the glucose solution?

  22. 1.10 Do calculations involving percentages. • How do we measure accuracy? • accuracy - the nearness of a measurement to an accepted value • precision - the agreement between a set of measurements Percentage Error O - A %E = ------------ X 100% A O - observed value A - accepted value How do we determine precision?

  23. 1.11Do calculations involving densities. • density - the mass per unit volume of a material • density = mass/volume • D(g/cm3) = m(g) / V(cm3) • D(g/mL) = m(g) / V(mL) • For gases • D(g/L) = m(g) / V(L)

  24. Sample Density Problem • Problem: Calculate the density of 10g of a material occupying a volume of 2.5mL. (10 pts) • D = m/V , m = 10g, V = 2.5mL 5 pts • D = 10g / 2.5mL 2 pts • D = 4 g/mL • (1pt) +(2pts) =3pts

  25. Sample Problems • Suppose you performed an experiment and found the volume of a 10g sample of aluminum to be 3.5mL. • Calculate the density of the sample using your data. • The accepted density of aluminum is 2.7g/mL. Calculate the percentage error of your measurements. A fruit drink is made by mixing 1.0 L of water with 25g of solid mix. What percent of the mass of the mixture is solid fruit mix?

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