Unit 1 Introduction to Chemistry

Transcription

1 Chemistry 1 West Linn High School Unit 1 Packet and Goals Name: Period: Unit 1 Introduction to Chemistry Unit Goals: As you work through this unit, you should be able to: 1. Identify characteristics of matter. (2.1) 2. Differentiate among the three states of matter. (2.1) 3. Define and be able to apply physical properties to physical change. (2.1) 4. Describe a mixture and explain how it can be separated. (2.2) 5. Explain the difference between an element and a compound. (2.3) 6. Understand the difference between physical change and chemical change. ( ) 7. Understand the law of conservation of mass. (2.4) 8. Understand the difference between qualitative, quantitative, accuracy and precision. (3.1) 9. Calculate percent error. (3.1) 10. Identify the correct precision (number of significant figures) of measurements taken from measurement devices including the use of scientific notation. (3.1) 11. Identify the number of significant figures in a measurement and use significant figures in calculations. (3.1) 12. List the SI units of measurement and common metric prefixes. (3.2) 13. Be able to convert from one SI unit to another using dimensional analysis. (3.3) 14. Be able to calculate density values from mass and volume data. (3.3) 15. Be able to construct a scatter plot graph from data, appropriately label axes, and calculate slope Reading: Chapter 2 (pp 32-58) Chapter 3: (pp 60-98) Key Terms: chemistry, matter, substance, mass, solid, liquid, gas, vapor, physical change, physical property, intensive property, extensive property, chemical reaction, reactants, products, chemical change, chemical property, Law of Conservation of Mass, element, compound, chemical symbols, mixture, solutions, phase, heterogeneous mixture, homogeneous mixture, qualitative, quantitative, precision, accuracy, percent error, meter, kilogram, absolute zero, liter, Kelvin, Celsius, conversion factor, dimensional analysis, significant figures, density Homework: Classwork and Labs Description Goals Score HW 1 Chapter 2 Reading Guide 1-6 Unit 1 Note Packet HW 2 HW 3 Chemical vs. Physical Properties, Elements, Compounds and Mixtures WS Qualitative vs. Quantitative, Accuracy vs. Precision WS Physical/Chemical Properties Activity 1-6 Separation Lab Unit 1 Goals 1-6 Quiz 8 Measurement Activity Aluminum Foil Lab HW 4 Significant Figures WS Formal Density Lab Unit 1 Exam HW 5 Metric Unit Conversions and Dimensional Analysis WS 12-14

2 2.1 Properties of Matter Describing Matter: Page 34 Chapter 2 A. Define an Extensive Property Give an example: B. Define an Intensive Property Give an example: C. Define a Substance D. What is a Physical Property? States of Matter: Page 36 A. Describe the following: Solid Liquid Gas How is a Vapor different from a Gas?

3 Physical Changes: Page 37 A. Define a Physical Change: List common words that describe a Physical Change: 2.2 Mixtures Classifying Mixtures: Page 38 A. Define a Mixture: B. What is the difference between a Heterogeneous Mixture and a Homogeneous Mixture? What is another name for a Homogeneous Mixture? C. What does the term Phase describe? Separating Mixtures: Page 40 A. What properties can be used to separate a mixture?

4 Sample Problem 2.1 ( Page 41) How could a mixture of aluminum nails and iron nails be separated? Example Problems 10. What physical properties could be used to separate iron filings from table salt? 11. Air is mainly a mixture of nitrogen and oxygen, with small amounts of other gases such as argon and carbon dioxide. What property could you use to separate the gases in air? 2.3 Elements and Compounds Distinguishing Elements and Compounds: Page 42 Define Element: Define Compound: Compounds can be, but Elements cannot. What is a Chemical Change? Distinguishing Substances and Mixtures: Page 44 If the composition of a materials is fixed,. If the composition of a material may vary,.

5 Fill in the following flowchart to describe how Matter is categorized: 2.4 Chemical Reactions Define Chemical Property: During a chemical change, Define Reactant Define Product List some clues that can be observed to tell if a chemical change has taken place: Define Precipitate Define Conservation of Mass

6 Chapter Using and Expressing Measurements Scientific Notation: It is expected that you know how to use scientific notation. If you need help or review, read through pages and complete Sample Problem 3.1 Qualitative vs Quantitative Observations Qualitative Observations are Descriptive and do not include a numerical measurement Quantitative Observations include a numerical measurement Accuracy, Precision, and Error: page 64 Define Accuracy Define Precision In the following, diagram an example of each set of concepts Good Accuracy, Good Precision Poor Accuracy, Good Precision Poor Accuracy, Poor Precision Precision and Measurements How precise a measurement is depends on the tool used to make the measurement. Precision is determined by the number of quantitative markers on the measuring tool. We always measure/estimate to one decimal place beyond the tools marks. Record each measurement with the correct precision based on the tool used

7 Define percent error Sample Problem 3.2 (page 65) The boiling point of pure water is measured to be 99.1 C. Calculate the percent error. Significant Figures: page 66 Define Significant Figures Determining Significant Figures in Measurements: page 67 Rule 1. Every nonzero digit in a reported measurement is assumed to be significant Example 2. Zeros appearing between nonzero digits are significant 3. Leftmost zeros appearing in front of nonzero digits are not significant. They act as placeholders. By writing the measurements in scientific notation, you can eliminate such placeholding zeros 4. Zeros at the end of a number and to the right of a decimal point are always significant 5. Zeros at the rightmost end of a measurement that lie to the left of an understood decimal point are not significant if they serve as placeholders to show the magnitude of the number **If such zeros were known measured values, however, then they would be significant. Writing the value in scientific notation makes it clear that these zeros are significant** SPECIAL CASE 6. There are two situations in which numbers have an unlimited number of significant figures. The first involves counting. A number counted is exact. The second situation involves exactly defined quantities such as those found within a system of measurement

8 Sample Problem 3.3 (page 68) How many significant figures are in each measurement? a. 123 m d. 22 meter sticks b. 40,506 mm e m c x 10 4 m f. 98,000 m Why have Significant Figures? All measurements have ERROR. This error needs to be communicated to other scientists These errors get passed on through calculations Our calculations can t be more precise than the measurements used in them! Significant Figures in Calculations: Page 68 In general, a calculated answer cannot be more precise than the least precise measurement from which it was calculated. The calculated value must be rounded to make it consistent with the measurements from which is was calculated. Sample Problem 3.4 (page 69) Round off each measurement to the number of significant figures shown in parentheses. Write answers in scientific notation a meters (four) b meter (two) c meters (two) Rules for Calculations: Page 70 Addition and Subtraction: The answer should be rounded to the same number of decimal places as the measurement with the least number of decimal places Multiplication and Division: The answer should be rounded with the same number of significant figures as the measurement with the least number of significant figures.

9 Sample Problem 3.5 (page 70) Perform the following addition and subtraction operations. Give each answer to the correct number of significant figures. a meters meters meters b meters meters Sample Problem 3.6 (page 71) Perform the following operations. Give the answers to the correct number of significant figures. a meters X 0.34 meters b meters X 0.70 meters c meters 2 / 8.4 meters d meters 2 / meter 3.2. Units of Measurement SI Base Units Commonly Used Metric Prefixes Quantity SI Base Unit Symbol Prefix Symbol Meaning Factor Length Mass Temperature Time Amount of substance Some common metric equivalents 1 km = 1000 m 1 m = 100 cm 1 m = 1000 mm 1 kg = 1000 g 1 g = 100 cg 1 g = 1000 mg 1 kl = 1000 L 1 L = 100 cl 1 L = 1000 ml 1 cm 3 = 1 ml 1 min = 60 s 1 h = 60 min Convert 25 km to m Convert kl to ml Convert L to cm 3

10 Density: Page 80 Define Density in words: Define Density as an equation: Carefully read all of page 80 on Density: What does Density depend on? Does Density depend on MASS? Does Density depend on VOLUME? Sample Problem 3.8 (page 82) A copper penny has a mass of 3.1 g and a volume of 0.35 cm 3. What is the density of copper? Water: Special Density The metric system has been designed to give a special value for the density of water Pure Water: 1 g of H 2 O = 1mL of H 2 O Pure Water: Density = 1 g/ml 3.3. Solving Conversion Problems Conversion Factors: Page 84 & 85 What happens when a measurement is multiplied by a conversion factor? Dimensional Analysis: Page 86 Define Dimensional Analysis:

11 Sample Problem 3.9 (page 86) How many seconds are in a workday that lasts exactly eight hours? Sample Problem 3.11 (page 88) Express 750 dg in grams Sample Problem 3.12 (page 89) What is the volume of a pure silver coin that has a mass of 14 g? The density of silver (Ag) is 10.5 g/cm 3. Sample Problem 3.14 (page 91) The density of manganese, a metal, is 7.21 g/cm 3. What is the density of manganese expressed in the units of kg/m 3? Sample Problem: Complex Dimensional Analysis Tina s car gets 35.0 miles per gallon on the freeway. She is driving from San Francisco to Boston (3050 miles away). She will spend an average of $3.97 per gallon of high-octane fuel. Assuming all her driving is on the freeway, how much will her trip cost in gas? Additional Conversions in Chemistry Temperature Celsius to Kelvin» # K = # ⁰C Kelvin to Celsius» # ⁰C = # K 273 Celsius to F» # ⁰F = (9/5)# ⁰C + 32

12 Journal and Warm-up: Remember to record; date and question for each warm-up problem. Show all work and edits to correct.