Scientific Measurement Chapters 3 Assignment & Problem Set

Transcription

1 Scientific Measurement Chapters 3 Assignment & Problem Set Name Warm-Ups (Show your work for credit) Date 1. Date 2. Date 3. Date 4. Date 5. Date 6. Date 7. Date 8.

2 Scientific Measurement 2 Study Guide: Things You Must Know Vocabulary (know the definition and what it means): (proper) scientific notation significant figures exact numbers rounding numbers qualitative quantitative precision accuracy error percent error density temperature absolute zero heat Learning Objectives: how to convert numbers between decimal notation and scientific notation how to add, subtract, divide, and multiply numbers expressed in scientific notation why significant figures are used for measurements how to read measurement scales to the correct number of significant figures how to determine the number of significant figures in a measurement which digit is the estimated digit in a measurement how to round a measurement to the correct number of significant figures how to express the correct number of significant figures when adding, subtracting, dividing, and multiplying measurements. the difference between qualitative and quantitative measurements the difference between precision and accuracy how to determine the error and percent error of a measurement common units used in the metric system (Table D) common prefixes (name, symbol, and value) used to modify metric units (Table C) the relationship between milliliters (ml), cubic centimeters (cm 3 ), and grams (g) how to calculate density how to convert between Celsius and Kelvin temperature scales the difference between temperature and heat Key Reference Tables Table C: Selected Prefixes Table D: Selected Units Table T: Important Formulas and Equations

3 Scientific Measurement 3 Read Chapter 3; skip the section on specific gravity, p72 Complete the Reading Assignment on Density Lab 2: Observing a Chemical Reaction Regents Tables Table C: Selected Prefixes Table D: Selected Units Table T: Important Formulas and Equations Warm-ups and problems will be collected before you take the test. Answer all problems in the space provided. For problems involving an equation, carry out the following steps: 1. Write the equation. 2. Substitute numbers and units. 3. Show the final answer with units. There is no credit without showing work. Qualitative vs. Quantative 1. Identify the following as quantitative or qualitative measurements: a. A flame is hot c. Wax is soft b. A candle has a mass of 90g d. A candle's height decreases 4.2 cm/hr. Accuracy & Precision 2. Three students made multiple weightings of a copper cylinder, each using a different balance. The correct mass of the cylinder had been previously determined to be 47.32g. Describe the accuracy and precision of each student s measurements. Mass of Cylinder (g) Lisa Lamont Lara Weighing Weighing Weighing Weighing Precise? Accurate? Error and Percent Error 3. A technician experimentally determined the boiling point of octane to be o C. The actual boiling point of octane is o C. Calculate the error and percent error. Scientific Notation 4. Write each measurement in scientific notation. a. the length of a football field, 91.4 meters b. the diameter of a carbon atom, meters c. the radius of Earth, meters

4 Scientific Measurement 4 5. Express the following numbers in proper scientific notation. a b c x 10-4 d x Express the following numbers in decimal notation a x 10 5 b x Solve each problem and express each answer in scientific notation. a. (4 x 10 7 ) x (2 x 10-3 ) c. (4.6 x 10 3 ) - (1.8 x 10 3 ) b. (6.3 x 10-2 ) d. (7.1 x 10-2 ) + (5 x 10-3 ) (2.1 x 10 4 ) 8. Solve each problem and express each answer in scientific notation. a. (5.3 x 10 4 ) + (1.3 x 10 4 ) c. (9.12 x 10-1 ) - (4.7 x 10-2 ) b. (7.2 x 10-4 ) (1.8 x 10 3 ) d x 10-3 x 10 6 Significant Figures 9. Determine the number of sig figs in each of the following measurements and calculation results. a. 12 basketball players c meter b square meter d meters 10. Round each of these measurements to three sig figs. a L c o C b cg d x 10 4 mm 11. Perform the calculation, express in proper sig figs, and round answer correctly. Don t forgets units. a. 8.7g g + 19g = b. 4.32cm x 1.7cm = c L L = d kg = e. 5.47m m m 3 =

5 Scientific Measurement Solve each problem and express each answer in proper scientific notation and sig figs. a. (5.7 x 10 4 ) x (5.94 x 10 3 ) d b. (52806) / (2.34 x 10-2 ) e c. (Honors) (9.16 x 10-1 ) (8.63 x 10-2 ) f. (Honors) ( ) ( x 10-4 ) 13. Water with a mass of 35.4 g is added to an empty flask with a mass of g. A rubber stopper is then put on the flask. The mass of the flask, stopper and water is g. Express the mass of the stopper to the correct number of sig figs. Metric System 14. What is the symbol and meaning of each? a. milli- b. nano- c. deci- d. cent- 15. How many grams are in each of these quantities? a. 1cg b. 1kg c. 1mg 16. From what unit is a measure of volume derived? 17. What is the volume of a paperback book 21cm tall, 12cm wide and 3.5cm thick? 18. (Honors) What is the volume of a glass cylinder with an inside diameter of 6.0cm and a height of 28cm? (The volume of a cylinder is given by the equation V = 3.14r 2 h, where r is the radius and h is the height) 19. Match the approximate mass with each item. a. peanut (1) 400cg b. pear (2) 50mg c. stamp (3) 60kg d. person (4) 150g 20. Which is larger? a. 1 centigram or 1 milligram b. 1 liter or 1 centiliter c. 1 calorie or 1 kilocalorie d. 1 millisecond or 1 centisecond e. 1 microliter or 1 milliliter

6 Scientific Measurement 6 Density 21. A student finds a shiny piece of metal that she thinks is aluminum. In the lab, she determines that the metal has a volume of 245cm 3 and a mass of 661g. Calculate the density. Is the metal aluminum? 22. A shiny, gold-colored bar of metal weighing 57.3g has a volume of 4.7cm 3. Is the metal bar pure gold? 23. (Honors) A piece of wood floats in ethanol but sinks in gasoline. Give a range of possible densities for the wood. 24. (Honors) The mass of a cube of iron is 355g. What is the mass of a cube of lead that has the same volume? (You will need to look up the densities of iron and lead on Regents Table S.) Temperature 25. Chocolate cookies are baked at 190 o C. Express this temperature in kelvins. 26. The boiling point of the element argon is 87 K. What is the boiling point of argon in degrees Celsius? 27. Which would melt first, germanium with a melting point of 1210K or gold with a melting point of 1064 o C? Review 28. Classify each of the following as a chemical or a physical change. a. grass growing b. sugar dissolving in water c. crushing a rock d. cooking potatoes e. bleaching clothes f. boiling water 29. How would you separate a mixture of ground glass and table salt?

7 Scientific Measurement 7 Density: Read Chapter 3, section 3.4 pages (you are not responsible for specific gravity, page 72), and answer the following questions. For numerical problems, show all work. All questions are worth one point for a total of 10 points. 1. What is the density formula? Define each symbol. 2. What are the most common units for measuring the density of solids and liquids? 3. Does the density of a substance depend on the amount of that substance? Explain. 4. Can density be used to identify a substance? Explain. 5. Explain, in terms of the density of the substances involved, why a helium balloon rises in air. 6. The temperature of a piece of silver is raised from 20.0 o C to 42.0 o C. a. Does its mass get bigger, smaller, or stay the same? b. Does its volume get bigger, smaller, or stay the same? c. Does its density get bigger, smaller, or stay the same? 7. A sample of iron has a mass of 23.2 g and a volume of 2.95 cm 3. What is its density? 8. The density of calcium can be found on Table S on the Regents Tables. If a piece of calcium has a mass of 412 g, what is its volume?