Unit 1: Science is a Verb

Transcription

1 Unit 1: Science is a Verb Student Name: Key Class Period: Page 1 of 47

2 Unit 1 Vocabulary: 1. Analysis: the step in the scientific method where data is used to solve a problem. 2. Coefficient: the number in FRONT of a formula. 3. Control: the conditions which remain constant during an experiment. 4. Conversion factor: a number or ratio (in fraction form) that is used to convert from one unit type to another. The given units cancel out, leaving the desired units. 5. Data: that which is measured or observed during an experiment. 6. Dependent Variable: the Y-axis variable that changes as a result of changing the independent variable. 7. Direct Relationship: a relationship where the increase of the independent variable results in the increase of the dependent variable. 8. Experiment: activity that tests the specifics of the hypothesis. 9. Exponent: a number that expresses a power, is written as a superscript X # 10. Extrapolation: extending the graph beyond the given data points to infer values beyond that which was plotted. 11. Given: information provided to you as a number and unit. 12. Hypothesis: an If-then-because statement used to design an experiment to test an idea. 13. Independent Variable: the variable on the X-axis the experimenter controls. 14. Indirect Relationship: a relationship where the increase of the independent variable results in a decrease of the dependent variable, or vice versa. 15. Interpolation: reading between plotted graph data points to infer a value. 16. Line of Best Fit: a straight line that best represents the slope of the date being analyzed. 17. Precision: the place value to which a measurement was made. 18. Problem: a specific issue that can be resolved through applying the scientific method. 19. Scientific Method: a series of logical processes designed to solve problems. 20. Significant Figures: the number of digits actually recorded by the measuring device while measuring. 21. Target: the desired result of a mathematical problem that you are solving. 22. Unit: a symbol which identifies the type of measurement that has been made. This is required after every measure number and calculation. 23. Variable: the value that changes during an experiment. Page 2 of 47

3 Unit 1 Homework Assignments: Assignment: Date: Due: Page 3 of 47

4 Topic: The Scientific Method Objective: How can problems be solved in a systematic method? The Scientific Method You have a problem? Then solve it using the Scientific Method (SciMet)! It is a logical sequence of steps designed to specifically solve problems. Pharmaceutical companies apply the SciMet in determining what the best medications for a condition are and what the best dosage is. Mechanics use the SciMet to diagnose and repair problems. Computer technicians use the SciMet to diagnose and repair problems. Doctors us the SciMet to diagnose and heal illness or injury. Forensic investigators use the scientific method to solve crimes. Page 4 of 47

5 Student name: Class Period: Please carefully remove this page from your packet to hand in. Scientific Method homework You arrive home afterschool and grab your CD player (yes, I m OLD school!), but nothing happens when you press Play. Use the SciMet to figure out what is wrong. 1. Match the statements below on the right with the parts of the scientific method on the right by connecting them with drawn lines. I. Problem Batteries are in correctly. II. Hypothesis Batteries are in wrong. III. Experiment Position of the batteries is NOT the problem IV. Data Checked position of the batteries against the diagram in CD player V. Draw Conclusion CD player won t work! 2. List two other possible hypotheses for the CD player not working. a. b. Page 5 of 47 Cont. s next page

6 3. For one of the hypotheses you created for question #2, explain how you could work through the SciMet to test the hypothesis you created. a. Your chosen hypothesis: b. Your experimental design to test your hypothesis: c. Expected results if your hypothesis is true: Page 6 of 47

7 Topic: Measurement Objective: How do we give dimension to the world around us? Measurement gives the universe meaning. How tall are you? How much do you weigh? How old are you? How fast can you run? How much volume do you displace? All these questions are designed to give us reference to the world around us. Metric System Units (Reference Table D): Symbol Name What it measures m Meter Distance (length height, width) G Gram Mass (how much matter contained) Pa Pascal Pressure (force exerted over an area) K Kelvin Temperature (avg. kinetic energy of system) Mol Mole Amount of substance (6.02 x things) J Joule Heat (Stored, or potential, energy of a substance) S Second Time (from one moment in a continuum to another moment) L Liter Volume (1 L = 1 dm 3 ; 1 ml = 1cm 3 ) Ppm Parts/million Concentration (mass of solute/mass of solvent x 1,000,000) M Molarity Concentration (moles of solute/l of solution) Page 7 of 47

8 Topic: Measurement Objective: How do we give dimension to the world around us? Metric Prefixes (Reference Table C): Factor Prefix Symbol Example (Mass) Example (Distance) 10 3 (thousand) Kilo- k 1 kg=2.2 lbs 1 km=0.621 mi 10 0 (one) g = ounces(oz) 1 m = 3.28 feet 10-1 (tenth) Deci- d 1 dg = oz 1dm = 3.94 inches(in.) 10-2 (hundredth) Centi- c 1 cg = oz 1 cm = in 10-3 (thousandth) Milli- m 1 mg = oz 1 mm = in 10-6 (millionth) Micro- µ 1 µg = oz 1 µm = in 10-9 (billionth) Nano- n 1 ng = oz 1 nm = in (trillionth) Pico- p 1 pg = oz 1 pm = in What unit is best used for: Measurement Prefix & Unit Why? Distance between cities kilometer Use instead of miles Volume of milk container liter Use instead of gal & qts Your weight (mass) kilogram Use instead of pounds Length of a pen centimeter Use instead of inches Mass of a candy bar grams Use instead of ounces Time for a class period seconds Use instead of hours Your height meters Use instead of feet Page 8 of 47

9 Student name: Class Period: Please carefully remove this page from your packet to hand in. Measurement homework 1. Measure the length of a paper clip on each ruler pictured below. The measurements will not be the same for each one, due to a difference in precision. Use the SAME paperclip for all three readings and record your measurements. to 1 cm to 0.1 cm to 0.01 cm Cont. s next page Page 9 of 47

10 2. For the following measuring devices, record the reading and the precision (place) the measurement was made to. (Ignore # of Sig Figs for now) cm 0.01 cm 3.0 cm 0.1 cm ml 0.01 ml 24.6 ml 0.1 ml Page 10 of 47

11 Topic: Math Rules for Chemistry Objective: How do we work with measuring numbers in science? Math Rules for Chemistry: 1. N 3 : No Naked Numbers! ALL measurements and answers to math problems MUST have units written after the numbers! 2. No work, No Credit! You must show all of the following when doing math problems: the original equation you use, the equation rearranged algebraically to solve for the variable you are looking for, the rearranged equation with #s and units substituted, and the final answer properly rounded with correct units. Uncertainty in Measurement: Measurements are made one place beyond where the measuring device is marked. For example, a ruler marked to the nearest tenth of a centimeter can be red to the hundredths place by estimating how far it is between the two lines the measurement falls between. Page 11 of 47

12 Topic: Math Rules for Chemistry Objective: How do we work with measuring numbers in science? Uncertainty in Measurement (Cont d): Page 12 of 47

13 Topic: Determining Precision Objective: How do we determine the precision of scientific numbers? 1. If the measurement has a decimal point in it, the precision is the place furthest to the right in the measurement. i. In the measurement cm, there is a decimal point, so the precision of the measurement is the furthest place to the right, or the thousandths place cm ii. In the measurement g, there is a decimal point, so the precision of the measurement is the furthest place to right, or the ten thousandths place g iii. In the measurement 330. ml, there is a decimal point, so the precision of the measurement is the furthest place to the right, or the ones place ml 2. If the measurement does NOT have a decimal point in it, the precision is the place where either the rightmost integer is, or where a zero with a line over it is located. i. The measurement 2300 km has no decimal point in it, so the precision is where the rightmost integer is, or the hundreds place km ii. For the measurement 23Ō0 km there is no decimal point, so the precision is where the zero with the line over it sits, or the tens place. 23Ō0 km Page 13 of 47

14 Topic: Significant Figures Objective: How do we determine the significance of numbers? Rules for Significant Figures (sig figs): The number of significant figures in a measurement equals the total number of digits from an including the first (leftmost) integer in the measurement all the way to the limit of the precision of that measurement. In the examples shown below the significant figures are underlined, the place values are italicized, and the precision is in bold. i. In the measurement cm, the first integer is the 2 in the tens place. The precision of the measurement is the thousandths place five significant figures (sig figs) ii. In the measurement 8000 sec, the first integer is the 8 in the thousands place. The precision is the thousands place one sig fig iii. iv. In the measurement 40. L, the first integer is the 4 in the tens place. The precision is the ones place. 40. L 2 sig figs In the measurement 2300 g, the first integer is the 2 in the thousands place. The precision is in the hundreds place g 2 sig figs v. In the measurement 23Ō0 g, the first integer is the 2 in the thousands place. The precision is in the tens place. 23Ō0 g 3 sig figs Page 14 of 47

15 Topic: Significant Figures Objective: How do we determine the significance of numbers? vi. vii. viii. ix. In the measurement L, the first integer is the 2 in the hundreds place. The precision is the tenths place L 4 sig figs In the measurement kg, the first integer is the 7 in the tenths place. The precision is the thousands place kg 3 sig figs In the measurement kj, the first integer is the 9 in the hundredths place. The precision is the hundred thousandths place kj 4 sig figs In the measurement mol, the first integer is the 5 in the hundredths place. The precision is the millionths place mol 5 sig sigs Page 15 of 47

16 Notes page: Page 16 of 47

17 Student name: Class Period: Please carefully remove this page from your packet to hand in. Significant Figures homework 1. On the examples below circle the place where the precision is and underline the significant figures in the measurements. Write the number of significant figures in the measurement to the right of each measurement. Measurement # of sig figs Measurement # of sig figs Measurement # of sig figs 2000 cm cm cm 3 2Ō00 cm cm cm 4 20Ō0 cm cm 5 3 cm cm cm cm cm cm cm cm cm 6 3Ō00 cm cm cm 5 90 cm cm cm cm cm cm cm 4 Cont. s next page Page 17 of 47

18 2. Write the following numbers to the noted precision or number of significant figures. Number Precision Answer Number Precision Answer Forty-two tenth 42.0 Three Hundred 3 sig figs 320. twenty Three thousand 2 sig figs 3Ō00 Seventeen 4 sig figs Zero decimal Sixteen 3 sig figs three thousand hundred 16Ō00 Six thousandth Zero decimal four thousandth Page 18 of 47

19 Topic: Rounding Numbers Objective: How do you round off the answers to math problems? Addition and Subtraction: Your calculated answer may only be as precise as the least precise of the measurements to be added or subtracted. Your answer must be rounded to the place of precision of the least precise of the measurements. Round the following number to the to nearest tenth to nearest hundredth to nearest one Rounded answer to nearest ten 20 Round the following number to the to nearest tenth Rounded answer to nearest one to nearest ten 100Ō to nearest hundred 10Ō00 Place Chart: Watch the Bozeman Biology Significant Figures video Page 19 of 47

20 Topic: Rounding Numbers Objective: How do you round off the answers to math problems? In the examples below, the place of precision is bold type in the measurements. Addition & Subtraction Examples: a) 33.5 cm tenths cm hundredths cm thousandths = cm Rounded = 42.4 cm Since TENTHS goes out the least far, round the answer to nearest TENTH. b) km thousandths km tenths = km Rounded = km Since THOUSANDS goes out the least far, round your answer to the nearest THOUSAND. c) 6700 ml hundreds ml tenths = ml Rounded = 6600 ml Since HUNDREDS goes out the least far, round your answer to the nearest HUNDRED. Multiplication and Division: If you have some measurements to Multiply or Divide, round to the fewest sig figs, counting from the leftwards side! The answer may contain only as many significant figures as the measurement with the least number of significant figures. Round the following number to the Rounded answer Round the following number to the to 4 sig figs to 6 sig figs to 3 sig figs to 5 sig figs to 2 sig figs to 3 sig figs 10Ō to 1 sig fig to 1 sig figs Rounded answer Page 20 of 47

21 Topic: Rounding Numbers Objective: How do you round off the answers to math problems? The sig figs in the following measurements are underlined. a) cm 4 sig figs x 9.22 cm 3 sig figs = cm 2 Rounded = 620. cm 2 Rounding answer to 3 sig figs, you need to place the decimal point to show that 0 is a sig fig. b) 2Ō0 cm 2 sig figs x cm 4 sig figs = cm 2 Rounded = 670 cm 2 Rounding answer to 2 sig figs makes ones place a place-holding 0 so that the 1 st two integers are sig figs. c) 30 g 1 sig fig / 3 ml 1 sig fig = 10 g/ml Rounded = 10 g/ml Sometimes you don t have to do anything. One sig fig is all that is needed. d) 30. g 2 sig figs / 3.0 ml 2 sig figs = 10 g/ml Rounded = 10. g/ml To show that the answer 10 has 2 sig figs, put a decimal after the ones place. e) 30.0 g 3 sig figs / 3.00 ml 3 sig figs = 10 g/ml Rounded = 10.0 g/ml To show that the answer 10 has 3 sig figs, take the answer to the tenths place. Page 21 of 47

22 Notes page: Page 22 of 47

23 Student name: Class Period: Please carefully remove this page from your packet to hand in. Rounding Homework Be sure to consider the number of significant figures or precision in each of the following problems. For this exercise, consider all numbers to be measurements. Include units with your answers. Write the UNROUNDED answer first, then the rounded answer, drawing a box around your rounded answer. 1. Addition rounding Problem Unrounded answer Rounded answer cm cm cm = cm 22.3 cm 32.0 MW MW = MW 32.0 MW g g g = g 0.66 g km km km = km km 345 mmol mmol = mmol 346 mmol cg cg = cg cg 2. Subtraction rounding Problem Unrounded answer Rounded answer mg mg = mg 16.6 mg cl cl = cl cl J J = J J kg - 16 kg = kg 363 kg km km = km km 960 cg cg = kg 960 kg Cont. s next page Page 23 of 47

24 3. Multiplication rounding Problem Unrounded answer Rounded answer KW x 2.2 hr = KWhr cm x 2.0 cm = cm kg x 200 m = kgm 381 m x 0.21 m = m $/L x 341 L = $ $/kg x 30 kg = 6000 $ Division rounding Problem Unrounded answer Rounded answer 4792 g / 24 cm 3 = Ō0 g/cm g / 1426 cm 3 = g/cm J / 300 g = J/g g / 24.2 km = g/km g / 9.11 mol = g/mol g / 10 L = g/l 5. OK, here is a practical density problem. Density = mass / volume. Show proper setup, units, and solve rounding with correct units. i. A ring is said to be pure silver (Ag) with a mass of g. Its volume (water displacement) is 1.95 ml. Calculate density of the ring. D=M/V g/1.95 ml = g/ml 10.5 g/ml to 3 sig figs ii. Based on the actual density of silver (Ag) from Reference Table S, could this ring be made entirely of silver? Explain your conclusion. Yes, as the Reference table gives silver s density as 10.5 g/cm 3 which is the same as 10.5 g/ml as it was tested in water displacement Page 24 of 47

25 Topic: Scientific Notation Objective: How is numerical data compressed for ease of use? Scientific Notation (Sci Not): Scientific Notation is expressing a number as a multiple of a power of ten. It is used to take loooooong numbers and compress them to more easily calculate the resulting answers without error. Writing of large numbers into Scientific Notation: Take the significant figures from the number, put them in the form N.NNN x 10 X power, where N.NNN represents the (in this case 4) sig figs and X is the number of places after the first significant figure back to the ones place. In the following examples the sig figs have been underlined. Model for large numbers: (First sig fig). (rest of sig figs) x 10 (# of places after the first sig fig back to the ones place) 1. The Earth is about 4,600,000,000 years old. Same number in Sci Not: 4.6 x 10 9 years i. The first sig fig is the 4, then the decimal point, then the other sig fig 6 (coefficient of 4.6) ii. After the 4, there are nine places back to the ones place. (exponent of 10 9 ) Page 25 of 47

26 Topic: Scientific Notation Objective: How is numerical data compressed for ease of use? 2. There are 33,400,000,000,000,000,000 molecules of water in one ml of water. Same number in Sci Not: 3.34 x molecules i. The first sig fig is the 3, then the decimal point, then the other sig figs 3 and 4 (coefficient of 3.34) ii. After the first 3, there are 19 places back to the ones place (exponent of ) Number Converted to Scientific Notation x 10 6 first sig figs 3, 2, & 4, then 6 places after the x 10 2 decimal point behind 300, means 3 sig figs x 10 2 only one sig fig so only coefficient x first sig figs 7 & 8, then 10 places after the 7 23Ō x 10 6 line over ten thousands place zero must be in coefficient Rewriting large numbers in scientific notation back into decimal form: Number 4.73 x 10 6 Converted to Decimal Form first write sig figs 4, 7, & 3. There will be a total of 6 places behind the 4, so place enough 0 s to account for the spaces 2.00 x Ō has three sig figs, so place line over second 0 for that 2.0 x Ō000 same as above, but 2.0 has only two sig figs 2 x is the only sig fig, so all 0 s are placeholders 3.71 x followed by 6 placeholders Page 26 of 47

27 Topic: Scientific Notation Objective: How is numerical data expanded for ease of use? Writing of small numbers into Scientific Notation: Write the sig figs in the same form as before, and count the number of 0 s, including the 0 in the ones place. This is a negative exponent. Model for small numbers: (first sig fig).(rest of sig figs) x 10 - (places before the 1st sig fig left to the ones place) 3. An atom of carbon weighs g. Same number in Sci Not: x i. The 1 st integer is 1, then a decimal, then the other sig figs (coefficient of 1.993) ii. There are 22 places in front of the 1 st integer heading left to the ones place (exponent of ) 4. The distance between H atoms in an H2 gas molecule is mm. Same number in Sci Not: 3.70 x 10-8 i. The 1 st integer is 3, then a decimal, then the other sig figs (coefficient of 3.70) ii. There are 8 places in front of the 1 st integer heading left to the ones place (exponent of 10-8 ) Page 27 of 47

28 Topic: Scientific Notation Objective: How is numerical data expanded for ease of use? Number Converted to Scientific Notation x places in front of 3 back left to the ones place (x 10-2 ) x 10-2 the 0 after the 3 needs to be in the coefficient (3.0) x 10-2 the two 0 s after the 3 need to be in the coefficient (3.00) x 10-6 there are 6 places in front of the 7 back left to the ones place x 10-3 you must include the 0 at the end as it is a sig fig Number Converted to Decimal form 8 x write 0.00 (for x 10-3 ) then the sig fig x add the 0 after the 8 b/c it shows up in the coefficient (8.0) 8.00 x add the two 0 s after the 8 b/c they show up in the coefficient (8.00) 4.3 x write (for x 10-4 ) then sig figs 4 & x must include 0 after 67 as 0 is a sig fig here Watch the Tyler Wallace Scientific Notation video Page 28 of 47

29 Topic: Scientific Notation Objective: How may we compare relative sizes in scientific notation? Comparing relative magnitudes of two numbers in Scientific notation: The larger the positive exponent, the larger the number will be. Circle the larger value in the pairs below. a) 2.0 x 10 6 or 3.0 x 10 4 b) 5.7 x or 1.3 x 10 7 c) 3.3 x 10 9 or 9.7 x 10 2 The smaller the negative exponent, the larger the number will be. Circle the larger value in the pairs below. a) 2.0 x 10-6 or 3.0 x 10-4 b) 5.7 x or 1.3 x 10-7 c) 3.3 x 10-9 or 9.7 x 10-2 Math using Scientific Notation: When adding or subtracting scientific notation numbers, convert to standard decimal form. I. 2.3 x x 10 7 = = II x x 10 3 = = When multiplying scientific numbers, multiply the coefficients first. Then add the powers of the exponents. I. 2.3 x 10 3 * 7.1 x 10 7 = (2.3)(7.1) x 10 (3+7) = x = x When dividing scientific numbers, divide the coefficients first. Then subtract the powers of the exponents. I x x 10 3 = (1.27)/(6.34) x 10 (5-3) = x 10 2 = 2.00 x 10 1 Page 29 of 47

30 Notes page: Page 30 of 47

31 Student name: Class Period: Please carefully remove this page from your packet to hand in. Scientific Notation homework Convert each of the following into scientific notation. Number Scientific Notation x x x x x x x x x x x x Convert each of the following into a standard decimal number. Scientific Notation Standard Decimal number 3.56 x , x ,200,000, x ,340,000,000,000, x x ,000,000,000,000,000,000,000,000,000,000, x x Ō x x ,020,000,000,000,000,000,000,000 Cont. s next page Page 31 of 47

32 Ksp is a measurement of the solubility of a salt. The larger the value of Ksp is, the more of that salt that can dissolve in water. Which of the following Ksp values would indicate a salt with the greatest solubility? a) 4.3 x 10-6 b) 5.7 x 10-7 c) 9.8 x 10-8 d) 3.2 x 10-9 Using the properties of Scientific Notation math on pg. 29 and your calculator, answer the following questions. a) 5.6 x x 10 8 = 5.2 x 10 8 b) 4.7 x 10 5 x 7.3 x 10-3 = 3.4 x 10 3 c) 1.00 x 10 8 / 4.7 x = 2.1 x 10-1 d) 8.2 x 10-4 x 3.01 x 10 5 = 2.7 x 10 1 Page 32 of 47

33 Topic: Conversion Factors Objective: How can units be used to solve problems for you? In chemistry you will be using many different formulas. If you know how units work and how they cancel out, you will be able to set up a problem correctly and be able to solve for what you need to find. We will learn here how using the metric system we will make conversion factors and use it to solve problems. To convert a measurement from one metric unit to another, you must know the difference in magnitude between the two prefixes and use that difference to create a conversion factor: Use Reference Table C. If there is no prefix (m, g, L, etc.) then the magnitude (power of 10) is The prefix below is underlined and the smaller unit is italicized. Watch Crash Course Chemistry Conversion, Sig Figs, & Sci Not video Page 33 of 47

34 Topic: Conversion Factors Objective: How can units be used to solve problems for you? To use the conversion factor: Given amount * or by the conversion factor = target (answer) 1. If the given unit is also the numerator unit on the conversion factor, DIVIDE to cancel it out. I m 1000 m/km = km 2. If the given unit is also the denominator unit on the conversion factor, MULTIPLY to cancel it out. I cm * 10 mm/cm = 10Ō0 mm NOTE: the number of significant figures in your answer equals the number of sig figs in the number you are converting! Conversion factor examples: Page 34 of 47

35 Student name: Class Period: Please carefully remove this page from your packet to hand in. Conversion Factors homework: Perform the following conversions, showing all work and units. Use the Reference Table C. 1. A medication dosage of 25.0 mg is prescribed. How many grams of medication is this? 2. One serving of an energy drink is L. How many centiliters is this? 3. A sign says your destination is 23.5 kilometers away. How many millimeters is this distance? Page 35 of 47

36 4. A cheeseburger contains an energy value of 359 kilocalories listed on the menu. a) How many calories are in 359 kilocalories? b) The unit of energy in the metric system is the joule. There are 4.18 joules in a calorie. How many joules does the above cheeseburger contain? Page 36 of 47

37 Topic: Scientific Graphing Objective: How can we make sense of data and use it to infer? Changing one thing in an experiment (independent variable) will often cause something else to change (dependent variable). 1. Measuring reaction rate as temperature is increased by applying heat: a. Temperature is the independent (manipulated) variable; reaction rate is the dependent variable 2. Measuring the volume of gas trapped in a cylinder as pressure is applied: a. Pressure is the independent (manipulated) variable; volume is the dependent variable Graphs should contain the following features: 1. X and Y axes with the independent variable on the X axis (with units) and the dependent variable on the Y axis (with units). 2. A numerical scale representing uniform increases in each variable. 3. A TITLE! Something that states the basic function of the graph (i.e. Reaction Rate vs. Temperature for graph 1 above) 4. Data points with error circles. These increase visibility and also represent a margin of error with the measurements. 5. A straight connecting line or a curve of best fit between the data points. Page 37 of 47

38 Topic: Scientific Graphing Objective: How can we make sense of data and use it to infer? Interpolation and Extrapolation: When data is graphed and a line (or a curve) drawn, you can infer about information within or outside of the data points. 1. Reading between the data points is called INTERPOLATION. 2. Extending your graph and reading outside your range is EXTRAPOLATION. When you do either, you must keep rules of precision. If your graph reads to the nearest one, your estimate is read to the nearest tenth. Page 38 of 47

39 Topic: Scientific Graphing Objective: How can we make sense of data and use it to infer? Best Fit Line (Average line): Notice a line of best fit gives approximately the same number of data points above and below the line. You should ALWAYS use a ruler and pencil to create a line of best fit. Relationships: Graphs show relationships between the independent and dependent variables. The relationship may be used to predict physical and chemical phenomena. 1. Direct relationship: as the independent variable is increased, the dependent variable also increases. 2. Indirect (inverse) relationship: as the independent variable is increased, the dependent variable decreases. Page 39 of 47

40 Topic: Scientific Relationships Objective: How can we tell between direct and indirect relationships? As the temperature is increased on a solution of salt dissolved in water, the solubility of the salt increases. This is a DIRECT relationship. As the pressure on a confined gas sample is increased, the volume of the gas will decrease. This is an INDIRECT (INVERSE) relationship. Page 40 of 47

41 Topic: Creating a good graph Objective: How can we create a good scientific graph? Creating a good graph: 1. Labeled axes: independent X axis, dependent y axis, with units 2. Title: describes the relationship between variables 3. Data Points: include error circles 4. Best Fit Line: shows average slope of linear data plotted 5. Scaled: regular interval spacing for both scales (may be different) 6. Size: graphed data should take up more than ¼ of the available graphing space. Larger graphs are easier to make and read. If NOT told to draw a best fit line, connect your data points. Page 41 of 47

42 Notes page: Page 42 of 47

43 Student name: Class Period: Please carefully remove this page from your packet to hand in. Graphing homework: A student created an experiment to find out how light energy affects the temperature of soil. A light was placed over a dish of soil with a thermometer. The soil temperature was measured at the start of the experiment before the light was turned on, and measured each minute for five minutes after that. The recorded temperatures are in the data chart below. 1. Identify the independent and dependent variables. a. Independent time (minutes) b. Dependent temp ( C) 2. Create a graph for the above data chart on the graph paper on the next page, including ALL elements of a proper graph. Draw a line of best fit for your plotted data. Cont. s next page Page 43 of 47

44 Page 44 of 47

45 Student name: Class Period: Please carefully remove this page from your packet to hand in. Graphing homework: 3. Extend the graph on pg. 44 past 6 minutes. What soil temperature would you predict at 6 minutes using this graph? Did you interpolate, or extrapolate your prediction? Explain. a) Soil 6 mins. _32.5 C to 33.0 C_ b) Interpolation or Extrapolation? c) Why? information was found outside plotted points 4. What would be the soil temperature at 3.5 minutes? Did you interpolate, or extrapolate your prediction? Explain. a) Soil 3.5 mins. b) Interpolation or Extrapolation? c) Why? information was found between plotted points 5. What type of relationship (direct or indirect) exists between these variables? How do you know? a) Relationship: direct b) Explain: as time increased so did temperature Page 45 of 47

46 Page intentionally blank Page 46 of 47

47 Notes page: Page 47 of 47