Unit 1 Physical Properties of Matter

Transcription

1 Name Period Unit 1 Physical Properties of Matter Grade/Content: 10 th /11 th Chemistry Next Generation Science Standards Addressed This is a foundational unit that does not specifically address any Next Generation Science Standards. New Jersey Core Curriculum Content Standards Addressed A.1 When making decisions, evaluate conclusions, weigh evidence, and recognize that arguments may not have equal merit A.2 Interpretation and manipulation of evidence-based models are used to build and critique arguments/explanations A.3 Engage in collaboration, peer review, and accurate reporting of findings B.1 Logically designed investigations are needed in order to generate the evidence required to build and refine models and explanations B.2 Show that experimental results can lead to new questions and further investigations B.3 Empirical evidence is used to construct and defend arguments B.4 Scientific reasoning is used to evaluate and interpret data patterns and scientific conclusions C.1 Refinement of understandings, explanations, and models occurs as new evidence is incorporated C.2 Data and refined models are used to revise predictions and explanations D.1 Science involves practicing productive social interactions with peers, such as partner talk, whole-group discussions, and small-group work D.2 Science involves using language, both oral and written, as a tool for making thinking public D.3 Ensure that instruments and specimens are properly cared for and that animals, when used, are treated humanely, responsibly, and ethically. Learning Goal # I will understand that matter is composed of particles that have mass, and I will be able to apply the Law of Conservation of Mass to explain observed changes in mass. I can differentiate causes of mass change from experimental error and provide unique explanations for each case. I can use observations from lab to explain how changes in mass do not violate the Law of Conservation of Mass. I can draw a particle diagram to illustrate changes in chemical and physical reactions. I can define matter, mass, and conservation of mass and use a balance to measure mass. 0.0 Even with help, no success with any content. 1

2 Learning Goal #2 I will understand that particles take up space, and I will be able to explain how particle arrangement affects the volume of objects. 4.0 I can explain how changes in volume occur in three dimensions and how this affects the spatial structure of systems. 3.0 I can differentiate volume from mass and understand that bigger does not always mean more massive. 2.0 I can illustrate the difference in volume for solids, liquids, and gases using particle spacing in particle diagrams. 1.0 I can define volume, identify units for volume, and measure liquid and solid volume with the appropriate tools. 0.0 Even with help, no success with any content. Learning Goal #3 I will understand that mass and volume are intrinsically related properties which are unique to each substance, and I will be able to determine this relationship by analyzing lab data. 4.0 I can analyze lab and graphical data to determine density, mass, and volume of unknown substances. 3.0 I can interpret slopes to compare densities of different substances. I can draw particle diagrams to represent substances with differing 2.0 densities. I can explain slope as a correlation of mass per unit volume. 1.0 I can define density and identify units for density. 0.0 Even with help, no success with any content. Learning Goal # I will understand that all measurements contain error, and I will be able to account for both how correct and how reproducible a measurement is. I can interpret a histogram and lab data to analyze lab error. I can create a plan to avoid lab error in the future. I can cite evidence and assess how lab error affected my results. I can interpret a histogram to identify trends in data. I can perform calculations with the proper number of significant figures. I can identify possible lab errors. I can construct a histogram to report results. I can accurately read a measurement and report it with the correct number of significant figures. I can define precision and accuracy. I can identify a histogram. 0.0 Even with help, no success with any content. 2

3 Unit 1 Overview We started the modeling chemistry course with a demonstration of a phenomenon that surprised most students. Then, I asked you to try to describe what is taking place at various stages of the reaction using particle models. The difficulty you encountered doing so should help you realize that you need to find better ways to describe change in matter. What new method have you learned and used to represent matter and change in matter? Next, we will develop the concept that mass is a property of an object that tells how much matter is present, and that the balance is the instrument used to measure mass. The episode - Mass - from the video series Eureka - Force and Motion, part 1, reinforces the idea that mass is a measure of the amount of stuff present in a sample of material. In the Mass and Change Lab, you will make observations about perceived mass changes in a variety of situations. In your own words, what is mass? Then, the discussion will shift to volume as another measure of how much stuff is present in a sample. You will review calculations of the volume of regular solids. In the next activity, Comparing Units of Volume, you will plot volume in ml vs. volume in cm 3 and analyze the slope of the graph. In our post-lab discussion we will consider the correlation between these two units, as well as the limitations of measurement and how best to report data. Then you will practice reading and reporting values from assorted instruments. Following that, we will complete the Mass & Volume lab, in which you will attempt to find a relationship between the mass and volume of sets of samples of iron and aluminum. You will find two distinct lines of best fit, corresponding to the densities of the two materials. We will discuss the concept of density, making the distinction between what density represents (the mass of a unit volume) and how you calculate it. Next, you will make comparisons of the mass, volume and density of pairs of objects based on particle representations. We ll further discuss how the slope of a graph has physical meaning. In the next activity, you will determine the density of carbon dioxide. The fact that the value is three orders of magnitude smaller than that of liquids and solids sets the stage for the discussion of an atomic model of matter that accounts for this difference. In the activity Thickness of a Thin Layer, you will apply the tools you have learned thus far (V=M/D, h = V/A) to calculate the thickness of sheet of aluminum foil this gives an upper limit for the size of atoms. You will be asked to estimate, and then calculate the number of layers of atoms in a sheet of aluminum. You will be able to make a better approximation when you see the experiment in which the thickness of a layer of oil is calculated. You will then visit the Size of Things website ( to relate the prefixes milli, micro, nano, and kilo to objects in the physical world. What do the prefixes milli-, micro-, nano-, and kilo- mean? (You might have to look this up if you don t know.) 3

4 Describing and Representing Matter In modeling chemistry, we ll frequently use diagrams to represent what we observe (macroscopic level) and what we can infer from what we observe (microscopic level). It is important for you to understand the difference between macroscopic and microscopic as well as the difference between an observation and an inference. Describe your understanding of the following words: Macroscopic Observation Microscopic Inference List your macroscopic observations of the demonstration: What microscopic inference(s) can you make from these observations? Draw a particle diagram representing the changing matter in the demonstration: Before During After 4

5 Mass and Change Lab Pre-Lab Questions Make predictions about the following scenarios. 1. Will the mass of a wad of steel wool change if it is stretched apart to about four times its original size? 2. When a soft drink is left in the freezer, what happens? The expansion of the water during freezing can burst the bottle or can. So it follows that a piece of ice will have a smaller volume when it melts. Will the mass change when the ice cube melts? 3. When some solutions combine, a solid (precipitate) forms. Will this cause the mass to change? 4. What happens to the mass of something when it burns? 5. What will happen to the mass of steel wool when it is heated over a Bunsen burner? 6. What happens when something dissolves? 7. What will happen to the mass when sugar dissolves in water? 8. What will happen to the mass when Alka-Seltzer dissolves in water? 5

6 Mass and Change Lab Procedures Goggles must be worn throughout the duration of this experiment. For Part 4, have heat gloves handy. Part 1: Stretching Steel Wool 1. Place a piece of steel wool in a weigh boat and find the mass. 2. Carefully pull the steel wool apart so that it is four times its original size and put it back in the weigh boat. 3. Record the mass of the expanded wool and the weigh boat. Part 2: Melting Ice 1. Determine the mass of a small beaker and 1 piece of ice. 2. Set the container aside and go on to the next part. 3. Determine the mass of the container and water after the ice has melted. Part 3: Mixing Solutions 1. Carefully pour each of the two solutions into two separate vials, until they are about ¼ full. 2. Find the mass of both capped vials together. 3. Carefully pour the contents of one vial into the other, and record the mass of both capped vials again. (One will be empty this time.) 4. Record your observations. Part 4: Heating Steel Wool 1. Find the mass of the steel wool in an evaporating dish and record. 2. Light the steel wool with the Bunsen burner using tongs. Rotate the steel wool so all sides are exposed to the flame. 3. Return the steel wool to the evaporating dish. If pieces of the steel wool fell off in the burning process, try to sweep them into the evaporating dish. 4. Record your observations. 5. Find the mass of the burned steel wool in the evaporating dish. 6. Discard the steel wool in the waste container provided. Part 5: Mixing Sugar and Water 1. Fill a vial about ½ full with water. 2. Put a small amount of sugar in the cap of the vial. 3. Put the vial with water and the cap containing sugar on the balance and record the mass. 4. Carefully pour the sugar from the cap into the vial - take care not to spill any. Shake the vial to dissolve the sugar. 5. When the sugar is completely dissolved, find the mass of the vial and its contents again. Part 6: Mixing Alka-Seltzer and Water 1. Repeat the same experiment as Part 5, but with a ¼ tablet of Alka-Seltzer in the cap of the vial instead of sugar. 2. Mass the vial with water and the cap with Alka-Seltzer. 3. Add the Alka-Seltzer to the water, and do not place the cap back on the vial. 4. When the tablet has completely dissolved, find the mass of the container and its contents again. 6

7 Use this page to create a data table to record your data and observations for the Mass & Change Lab. Include at least: (1) the name of each part of the lab, (2) your raw data, (3) mass changes observed, and (4) other observations. 7

8 Mass and Change 1. When you pulled the steel wool apart, you found that the mass was unchanged. But, when you heated the steel wool, you found that the mass changed. Explain. Draw diagrams (at the simple particle level) of the steel wool before and after you pulled it apart. before after Draw diagrams (at the simple particle level) of the steel wool before and after you heated it. before after 2. When ice melts, the volume of water is smaller than that of the ice. How does the mass of the water compare to the mass of the ice? Draw diagrams (at the simple particle level) of the ice and water. Use small circles to represent the H 2 O particles. before after 8

9 3. Draw diagrams (at the simple particle level) of the two solutions before and after you mixed them together. before after 4. When the sugar dissolved in the water, you found that the mass remained unchanged. When the Alka-Seltzer dissolved in the water, the mass of the system changed. Explain. Draw diagrams (at the simple particle level) of each of the materials before and after it was dissolved. sugar dissolving in water Alka-Seltzer dissolving in water before after before after 5. State the Law of Conservation of Mass. Then, explain what it means in your own words. Use diagrams if it helps your explanation. 9

10 Histogram Practice Go to the website and read the article on histograms to answer the following questions. 1. How are values graphed in a histogram? 2. What information does a histogram show about the data with respect to the mean of the data? 3. In real life situations, how are data graphed for a histogram plot? 4. What is an advantage to using histograms? Click the link for Shodor Histogram Page at the bottom of the website to answer the following questions: 5. What is the mean body fat from the 252 Men dataset? 6. Scroll down below the histogram mentioned above so you can see the data table. 7. Add Lance Armstrong with 4% body fat. Click update histogram right below the actual graph. What is the new mean body fat? 8. Now add Brian Urlacher s body fat of 6.2%. What is the new mean? Part II. Make your own histogram. 9. A pharmaceutical production worker at a major drug company obtained the following amounts of purified antibody to bovine protein. Create your own histogram from the data (in grams) Think About It: How large are your bins? What is the frequency for each bin? 10

11 Comparing Volume Units During this activity, you will explore the relationship between the volume units of ml and cm 3. Volume in cm 3 can be calculated using the formula: area of the base (cm 2 ) x height. Volume will be measured in milliliters using a graduated cylinder. Example of calculated volume in cm 3 : Student uses a square container measuring 10 cm x 10 cm and filled to a height of 2 cm. Area of container would equal length (10 cm) x width (10 cm). Area (100 cm 2 ) x height (2 cm) = a volume of 200 cm 3. Procedure: 1. Using selected container, make whatever measurements necessary for finding the area of your base. 2. Pour water into the container and measure the height of the water. 3. Pour the water from the container into a graduated cylinder and carefully measure the volume of the water in ml. Be sure to report your measurement from the graduated cylinder with the correct number of significant figures. Record this value in your data table. 4. Once you have calculated the volume of the water and used a graduated cylinder to measure the volume of the water, repeat the process with a new container. 5. Carefully record all of your data in a data table. Then, create a graph with volume in cm 3 on the x-axis and volume in ml on the y-axis. Plot your data points for each container. 6. Draw a best-fit line (doesn t have to go through points, but should be the best representation of the data set). 7. Calculate the slope of the line and write the equation for the line, as shown in the calculations section. Data table: 11

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13 Calculations: Show the 4- step process for writing the equation for the best-fit line as follows: 1. Start with y = m x + b 2. Replace y, and x with chemistry variables from graph; replace m and b with values (and units) from graph for slope and intercept. Volume (ml) = (slope) x (2 nd volume in cm 3 ) + intercept 3. Decide if b (intercept) is significant. This value conveys the amount of error in the measurements. b x100 % (Y-max = largest Y value from data table) Y max Rule: if intercept is less than 5% of Y-max, drop from final equation; if greater than 5%; keep as part of the final equation. 4. Write the final equation of the line. Conclusion: 1. What information is conveyed by the slope of the line? 2. What errors in your technique could cause the line not to go through zero? Be specific. 13

14 Accuracy & Precision Accuracy means Precision means To determine the accuracy of measurements, what do you need to know? To determine the precision of measurements, what do you need to know? What is percent error? How can it be calculated? Does percent error convey the accuracy or the precision of a measurement? Significant Figures What does significant mean when we re discussing significance in measurements or significant figures? In your own words, describe what significant figures are and why they re useful. Using the thermometer to the right, explain how to report the temperature with the correct number of significant figures. 14

15 Briefly describe what you did during the notecard/ glug measurement activity? What did you learn from the notecard/ glug measurement activity? In your own words, explain the rule for multiplying or dividing while maintaining the proper number of significant figures. Show an example below. In your own words, explain the rule for adding or subtracting while maintaining the proper number of significant figures. Show an example below. 15

16 Reading Scales For each of the following, write the place value to which the measurement can be read based on the graduations (markings) on the measuring instrument, then write the correct reading for the measurement. Place Value Reading

17 For each of the volume devices below record the scale reading and indicate the uncertainty in the measurement (± _). scale reading uncertainty scale reading uncertainty scale reading uncertainty

18 scale reading uncertainty scale reading uncertainty 18

19 Significant Figures Practice Count the number of significant digits in each number , ,100 Write rules for determining whether or not a zero is a sig fig. You may use examples from the section above or make up your own. Round each of the numbers to the number of significant digits specified in parentheses ,405 (2) (3) 13. 5,402,659 (1) (3) (2) (1) (3) (1) ,203 (4) (3) 19

20 When calculating with sig figs, the answer can only be as specific as the least specific value. For addition and subtraction, line up the decimal points and find the left-most decimal place of the numbers. Round your answer to that place value Rounds to: Add these numbers. Show the set up, line up the decimal points, and circle the digit that will cause you to round as shown above When multiplying and dividing numbers, your answer is rounded to the number of significant digits of your least specific number x 386 = = (with 3 s.f.) 5 s.f. 3 s.f. Least precise Multiply or divide the numbers using a calculator. (1) Give the calculator answer, (2) write how many significant figures the answer needs to be rounded to, and (3) give the rounded answer x (calculator) (s.f.) (rounded answer) x x x

21 Mass & Volume During this activity, you will explore the relationship between the mass and volume of differently-sized pieces of specific substances. How can you determine the masses of the objects? How can you determine the volumes of the objects? Before you begin the lab, plan your procedure below. (No, you don t need exactly 8 steps.) Procedure: Data table: (remember units and sig figs!) 21

22 Construct your graph with mass in grams on the y-axis and volume in cm 3 on the y-axis. 22

23 Calculations: 1. Determine the slope of each line (refer to your work from the volume units lab if you need a refresher). 2. Determine whether the b-intercept is significant for each line. 3. Write the final equation for each line. 4. For each substance, what is the mathematical relationship between the two variables? Conclusion: 1. What information is conveyed by the slope of the line? 2. What errors in your technique could cause the line not to go through zero? Be specific. 23

24 Mass, Volume, and Density In these problems, you will make comparisons of mass, volume, and density of pairs of objects based on particle diagrams. Then you will relate the density of objects to the graph of mass vs. volume. 1. Study the matter shown in Figure 1. Each dot represents a particle of matter. [Assume the particles are uniformly distributed throughout each object, and particles of the same size have the same mass.] Figure FIGURE 1 1 A A B B a. In the table below, show how the masses, volumes, and densities of A and B compare by adding the symbol <, >, or = to the statement in the second column. b. Explain your reasoning for each answer in the last column. Property Relationship Reasoning Mass A B Volume A B Density A B 24

25 2. Study the matter in Figure 2. [Assume the particles are uniformly distributed throughout each object, and particles of the same size have the same mass.] a. In the table below show how the masses, volumes, and densities compare by adding the symbol <, >, or = to the statement in the second column. b. Explain your reasoning for each answer in the last column. FIGURE 2 A C B Property Relationship Reasoning Mass A B A C Volume A B A C Density A B A C 3. Is object E or object F more dense? [Assume the particles are uniformly distributed throughout each object, and particles with a larger size have a larger mass.] Explain your reasoning. E F 25

26 4. In Figure 4 below, a graph shows the relationship between mass and volume for two substances, A and B. Use the graph to answer questions about these two substances. Mass (g) FIGURE 4: Mass and Volume Relationships Substance A Substance B Two Pan Balance A B volume (ml) a) You have built a simple two-pan balance shown above to compare the masses of substances A and B. What would happen to the balance if you put equal masses of A and B in the two pans? Equal volumes of A and B in the two pans? Explain your reasoning. b) Find the slope of the line for both A and B using correct units. State the physical meaning of the slope for each substance. c) If you put 10.0 ml of A in one balance pan, what mass of B would you need in the other pan to make it balance? Explain your reasoning. 26

27 d) If you put 35.0 ml of B in one balance pan, what volume of A would you need in the other pan to make it balance? Explain your reasoning. e) Water has a density of 1.00 g/ml. Sketch the line representing water on the graph in Figure 4. f) Substances that are less dense in comparison to the other substance(s) float. Substances that are more dense in comparison to the other substance(s) sink. Determine whether substance A and B will sink or float when placed in a bucket of water. A: sink float B: sink float (circle correct response) Defend your answer using the m-v graph, and your outstanding understanding of density. 27

28 Refer to the table of densities at the right to answer the following questions. Substance Density (g/ml) Aluminum 2.70 Titanium 4.54 Zinc 7.13 Tin 7.31 Iron 7.87 Nickel 8.90 Copper 8.96 Silver Lead Mercury Gold Sketch a graph of mass vs. volume for titanium, copper and mercury. 6. You made some cubes out of each metal in the table that each measures 2.00 cm on every side. (all except mercury why can t you make a cube of mercury?) a. What is the volume of each cube in cm 3? in ml? V = cm 3 V = ml b. Find the mass of these metal cubes: (Show your work.) lead cube nickel cube zinc cube 7. Alicia s cheapskate boyfriend gave her a ring he claims is 24 carat gold. Alicia is skeptical. After chemistry class the next day she measures the mass of the ring to be grams, finds the volume of the ring by water displacement (initial volume was 42.2 ml and final volume was 43.7 ml), and then calculates the density of the ring. Should she treasure the ring as his first truly generous gift to her, or throw it at him the next time he walks by? Defend your answer. 8. A student filled a graduated cylinder with water and read the meniscus at 25.8 ml. The student then dropped a solid material into the graduated cylinder and the water level rose to 35.9 ml. If the solid material had a density of 2.99 g/ml, determine the mass of the solid object. 28

29 More Density Practice Refer to the table of densities on the previous page of this worksheet to answer these questions: You have some iron wire, copper wire, and titanium wire (all the same gauge, or diameter). Your lab group measured out a length of wire that is exactly 10.00g for each type of metal wire. a) Which of these 3 metal wires would be the longest? b) Which of these 3 metal wires would be the shortest? c) Explain your reasoning for answers a) and b). d) If every 1.0 cm length of the titanium wire has a mass of 0.15 g, how long would the 10.00g wire be? (Hint: write a conversion ratio for the two quantities you are working with) e) What is the diameter of the titanium wire? (Hint: diameter is related to volume; assume it is a cylinder geometry! Yay!) 29

30 Applied Density Problems 1. Determine the density of each metal. Show all your work and include appropriate units. 2. From the graph, estimate a. the mass of 8.0 cm 3 of metal A. b. the volume of 70 g of metal B. c. Mark on the graph how you found the answers above. 3. Use the density of B as a factor to determine the answer to 2b. Show the set-up including how the units cancel. 30

31 4. Ethanol has a density of g/cm 3. a. What is the mass of 225 cm 3 of ethanol? b. What is the volume of 75.0 g of ethanol? 5. What is the density of water in g/ml? What does that mean? 6. The cup is a volume widely used by cooks in the U.S. One cup is equivalent to 237 cm 3. One cup of olive oil has a mass of 216 g; what is the density of olive oil? 7. What would you expect to happen if the cup of olive oil in question 6 is poured into a container of ethanol? Why? Gold has a density of 19.3 g/ cm 3. A cube of gold measures 4.23 cm on each edge: 8. What is the volume of the cube? 9. What is its mass? How many significant figures should you include in your answer and why? 10. A standard backpack is approximately 30cm x 30cm x 40cm. Suppose you find a hoard of pure gold while treasure hunting in the wilderness. How much mass would your backpack hold if you filled it with the gold? An average student has a mass of 70 kg. How do these values compare? 31

32 Density of a Gas Activity As seen in a prior lab, Alka-Seltzer dissolves in water and produces a gas (CO2). This activity allows you to determine the density of the gas produced. The gas produced will be collected by water displacement. The activity uses a collection apparatus that s connected to a bottle filled with water submerged in a pneumatic trough. Care must be taken not to spill any of the contents of the tube before or after the gas is generated. Procedure: 1. Mass the test tube (25 x 150 mm) filled 1 /4 with water, and the sample of Alka-Seltzer. 2. Drop the Alka-Seltzer into the water in the test tube, secure the stopper in the test tube and allow the gas to bubble into the collection bottle. See diagram at right for lab set up. 3. Be sure the collection bottle is completely full, with no air bubbles. 4. When reaction is complete, re-mass the test tube and contents to determine the difference. 5. Determine a method of measuring the gas in the bottle. (there are two equally good ways to do this) Data table: Mass A.S. / water before grams - Mass A.S. / water after grams = Mass of gas grams (record mass change to the nearest 0.01g) 32

33 Calculations: Use the mass and volume of the gas to determine the density. M V Density Show your set-up below. Label your answer. Conclusion: 1. What was your value for the density of CO2? How did it compare to the accepted value of 2.0 x 10-3 g/ml.? 2. Draw a particle diagram of the CO2 gas produced in reaction that is consistent with your value of density. 3. Draw a particle diagram of the CO2 gas that represents its density in comparison to other substances. 33

34 Thickness of a Thin Layer In this activity you will use information learned from prior labs to accurately determine the thickness of 2 sheets of aluminum foil. The rulers used to measure height in our volume lab would not be an acceptable option, but you could determine this value indirectly. Remember the formula, V = A x h. Rearrange this formula to determine the height (thickness) of our foil. Think what measurements you would have to make to determine the area of your foil. The density of aluminum is 2.70 g/cm 3. Remember how you have used density as a factor to convert between mass and volume. Procedure: 1. Use ruler to measure the width and length of your regular foil sample. (the area) 2. Carefully fold the foil into a small square so that it fits neatly on your balance pan. 3. Mass your sample of foil to nearest.01 g. 4. Carefully unfold the foil to its original shape. 5. Begin calculations. 6. Repeat for the piece of heavy-duty foil. Data table: 34

35 Calculations (show set-ups for each sheet of foil, label answers, include units): 1. Calculate the area of the foil (appropriate number of sf s). 2. From the mass and density, calculate the volume of the foil. 3. From the volume and the area, determine the thickness of the foil. Conclusion: 1. Why would the use of a ruler not be effective to measure the thickness of your foil? 2. In the Mass and Volume lab, we used water displacement to measure volume. Could this method of measurement have been used to find the volume of your foil? Explain. 3. The aluminum foil must be at least one atom thick (actually, there are many layers of atoms in the foil). Use your values for regular and heavy-duty foil to determine the maximum size of an aluminum atom. Explain briefly how you obtained your answer. 35

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37 Size of Things For this activity, you will need to go to the site to answer the following questions. Part 1 Real World Click on the link to Real World; make sure that you are looking at the sheet of graph paper. Each of the tiny squares on the paper is 1 mm (10-3 m) on a side. Examine the objects whose approximate size is given (~ 100 mm means the object is approximately 100 millimeters wide). 1. Using the graph paper as a measuring tool, estimate the diameter of the following in mm: quarter golf ball ping pong ball. 2. Use the ruler below the objects to estimate the diameter of each in inches. quarter golf ball ping pong ball 3. How long is the 5 Euro bill in mm, in cm, in inches? Part 2 Micro World Go to the top of the page and click on the micro link. Each of the tiny squares on the graph paper is 1 µm (10-6 m) on a side. Examine the objects whose approximate size is given (~ 10 µm means the object is approximately 10 micrometers wide). 4. Estimate the length of the paramecium in µm. You might have to use the Pythagorean Theorem to find this. Use the conversion factor 1m = 10 6 µm to change this length to m. 5. Why is it more convenient to express this value in µm? 6. Lower on the page are some drops from an inkjet printer with a resolution of 1200 dpi. Estimate the diameter (in µm) of such a drop 37

38 7. Estimate the length of the left-most human chromosome. 8. The author shows the thickness of a sheet of aluminum foil. 9. What is this in µm? Use the conversion factor 1m = 10 6 µm to change this thickness to m. 10. Now, convert this thickness to cm (1m = 100 cm). How does this compare to the value you obtained? Part 3 Nano World Go back to the top of the page and click on the nano link. Each of the tiny squares on the graph paper is 1 nm (10-9 m) on a side. Examine the objects whose approximate size is given (~ 10nm means the object is approximately 10 nanometers wide). 11. Scroll down to find the circle that approximates a globular protein. Estimate the size of a globular protein in nm. Use the conversion factor 1m = 10 9 nm to convert this value to meters. It would be more convenient to express this value in scientific notation. Do so Estimate the length (in nm) of a single wall nanotube, an engineered molecule containing carbon atoms 13. Roughly how many times larger is the smallest virus than a buckyball? 38

39 Part 4 Kilo World Go back to the top of the page and click on the kilo link. Each of the tiny squares on the graph paper is 1 kilometer (10 3 m) on a side. Examine the map of a portion of Massachusetts. 14. Estimate the distance (in km) between Boston and Cambridge. 15. Scroll down to find the ruler. Use the ruler on the sheet to determine a conversion factor between miles and kilometers. km = miles 16. Scroll down to the next map. Estimate the length (in km) of Nantucket Island. Use the conversion factor from above to change this length to miles. 17. If you could walk a mile in 30 minutes, how long would it take you to walk the length of this island? Show your work. 18. Lower on the page is a satellite photo of a portion of the Rodeo-Chediski fire. Nearly 500,000 acres of forest burned. Use the green square of the page to convert this area to km 2. Show your work, including your conversion factor. 39

40 Unit 1 Objective Check Objectives Prove It! 1. Define mass. Define volume. Give appropriate units for each. 2. Explain how to measure the mass of a solid object and the mass of liquid. Explain how to record the value of an object s mass in a manner consistent with the limit of precision of the measuring tool. 3. Represent data using a histogram; use the histogram to interpret trends in the data. 4. Use experimental evidence to explain the law of conservation of system mass. 40

41 5. Explain how the volume of a container (in cm 3 ) to the volume of liquid it contains (in ml) are related. Use experimental and mathematical evidence to support your claim. 6. Recognize that instruments have a limit to their precision; relate the data recorded to the quality of the measurement. 7. Explain how to round off calculated values to the appropriate number of significant figures. Show an example. 8. Explain how to write the equation of a line when given a mass v. volume graph. Explain what the slope means. 41

42 9. Recognize that density is a characteristic property of matter. How can density be used to identify unknown substances? 10. Use density as a conversion factor between mass and volume; show examples of converting mass to volume and vice-versa. 11. Use particle diagrams to represent solids, liquids and gases in a way that is consistent with their densities. 42

43 Learning Goal Reflection: Learning Goal # I will understand that matter is composed of particles that have mass, and I will be able to apply the Law of Conservation of Mass to explain observed changes in mass. I can differentiate causes of mass change from experimental error and provide unique explanations for each case. Prove it: Using the classroom data from the mass change, identify outliers, which groups were accurate, which groups were precise, and provide a list of reasons for any discrepancies in the data. I can use observations from lab to explain how changes in mass do not violate the Law of Conservation of Mass. Prove it: Draw a particle diagram for the burning of steel wool that accounts for changes in mass measured during the reaction. I can draw a particle diagram to illustrate changes in chemical and physical reactions. Prove it: Draw a particle diagram for two different liquids reacting to form a new liquid and releasing a gas. I can define matter, mass, and conservation of mass and use a balance to measure mass. 1.0 Prove it: Matter -> Mass -> Conservation of Mass -> 0.0 Even with help, no success with any content. Learning Goal # I will understand that particles take up space, and I will be able to explain how particle arrangement affects the volume of objects. I can explain how changes in volume occur in three dimensions and how this affects the spatial structure of systems. Prove it: Draw a particle diagram that shows an ice cube. Draw the same ice cube completely melted and draw the same ice cube as a vapor. Account for the law of conservation of mass in your diagrams and explain the difference (or if there s a difference) in volume and mass. I can differentiate volume from mass and understand that bigger does not always mean more massive. Prove it: 1. Which takes up more space, a 1 kilogram of cookies or 1 kilogram of feathers? Explain. 2. If you were being paid by the liter for containers of liquid, would you rather sell 20 grams of water or 20 grams of mercury? Explain. I can illustrate the difference in volume for solids, liquids, and gases using particle spacing in particle diagrams. Prove it: Draw a particle diagram for a solid, liquid and a gas. 43

44 I can define volume, identify units for volume, and measure liquid and solid volume with the appropriate tools. Prove it: Volume -> 1.0 Units of Volume -> Tool for measuring volume-> Describe how to measure the volume of a liquid. Describe how to measure the volume of a solid. 0.0 Even with help, no success with any content. Learning Goal #3 I will understand that mass and volume are intrinsically related properties which are unique to each substance, and I will be able to determine this relationship by analyzing lab data. I can analyze lab and graphical data to determine density, mass, and volume of unknown substances. Prove it: An piece of an unknown metal has a mass of 355 g and displaces 50 ml of liquid in a graduated cylinder. Using the following mass and volume data identify the substance

45 3.0 I can interpret slopes to compare densities of different substances. Prove it: Which substance has a higher density, substance A or substance B? Explain and prove your answer mathematically. Mass (g) FIGURE 4: Mass and Volume Relationships Substance A Substance B volume (ml) I can draw particle diagrams to represent substances with differing densities. Prove it: A substance X has a density of 5g/ml and substance Y has a density of 2 g/ml. Both are solids. Draw particle diagrams that show the 2.0 difference between substance X and substance Y s densities. I can explain slope as a correlation of mass per unit volume. Prove it: Explain how to calculate the density of an object from a list of mass and volume data. I can define density and identify units for density. 1.0 Prove it: Density-> Units of density-> 0.0 Even with help, no success with any content. 45

46 Learning Goal #4 4.0 I will understand that all measurements contain error, and I will be able to account for both how correct and how reproducible a measurement is. I can interpret a histogram and lab data to analyze lab error. Prove it: Draw a histogram for the following change in mass data: 1 g, 2 g, 1 g, 3 g, -8 g, 5 g, 0 g. Identify outliers, identify two sources of error that could explain these outliers, and explain what you think the change in mass for this experiment should be based on your histogram. I can create a plan to avoid lab error in the future. Prove it: You are required to mass out exactly grams of sugar to get your ice tea to the perfect sweetness. Explain what steps you would take using laboratory equipment to ensure you got this amount of sugar into your cup of tea. I can cite evidence and assess how lab error affected my results. Prove it: Choose an experiment that you have performed in this chapter. Identify the sources of error that affected your results and how they affected your results. I can interpret a histogram to identify trends in data. Prove it: Describe the trend in the data and identify possible outliers. 3.0 I can perform calculations with the proper number of significant figures. Prove it: = 3.4 x 8.213= = /56.8 = I can identify possible lab errors Prove it: List five examples of the most probable mistakes that can happen when measuring mass and/or volume data in the lab that will add error into measured data. I can construct a histogram to report results. Prove it: Draw a histogram for the following data: 1 g, 2 g, 1 g, 3 g, -8 g, 5 g, 0 g. I can accurately read a measurement and report it with the correct number of significant figures. Prove it: What is the volume of water in the graduated cylinder below? 46

47 1.0 I can define precision and accuracy. Prove it: Precision-> Accuracy-> I can identify a histogram. Prove it: Describe what a histogram looks like. 0.0 Even with help, no success with any content. 47