Welcome to Chemistry I Chemistry th I-4 Block: 1/6/14 Due: • Syllabus signed-place in tray Objectives: •Discuss and Apply Lab Safety Rules •Review Scientific Skills-graphing Homework: • Review Lab Safety Rules-safety test tomorrow • Graphing Assignment Safe, Engaging, and Productive Classroom? What is chemistry ?-4th Block What is chemistry? •Study of Matter -Identify and classify matter based on its composition/make-up. -Analyze the chemical and physical changes of matter. Elements: Different Atoms Classification of Matter Elements: Different Atoms Scientific Skills Objectives • I can distinguish between the independent and dependent variable in an experiment. • I can distinguish between quantitative and qualitative data. • I can distinguish between accurate and precise results. • I can plot and interpret experimental data. • I can convert between measurements. • I can establish a relationship between significant figures and accuracy of a measurement. • When calculating with measurements, I can express and answer to the correct degree of accuracy. • I can apply the density equation to problems. Experimental Variables • Independent variable -Variable “I” control; manipulated during the expt. -Graph on x-axis • Dependent Variable -Variable that “depends” upon the independent variable. -Graph on y-axis Hummingbird Graphing Assignment Types of Experimental Results Qualitative Results: (quality) -results observed through your senses. -subjective results Quantitative Results:(quantity) -measurements/calculations from an experiment. -definitive results Measurements and Conversions Measurements and Conversions Measurements and Conversions Scientific Skills Review: Bell Ringer *Use data from data table on worksheet to answer questions: 1. What is the independent variable in this experiment? 2. What is the dependent variable in this experiment? 3. a. A qualitative observation from this experiment? b. A quantitative observation from this experiment? Scientific Skills Review: Bell Ringer *Use data from data table on worksheet to answer questions: 1. What is the independent variable in this experiment? 2. What is the dependent variable in this experiment? 3. a. A qualitative observation from this experiment? b. A quantitative observation from this experiment? Measurements and Conversions Measurement Conversion Lab Purpose: • To make accurate measurements and conversions. • Must show work(your thinking!) for conversions to receive full credit. Measurement Conversion Lab Measurements and Conversions Measurement Conversions Bell Ringer: Scientific Skills 1. a. b. c. d. 2. Make the correct unit conversions. 0.0079 L = _____mL 500 g = ____kg How many meters are in 22.5 in? How many ft are in 13.5 km? Determine if the experimental masses is/are accurate, precise, or both? The actual value of the rock is 2.5 grams. Mass (g) Trial 1 Trial 2 Trial 3 Trial 4 rock 4.0 4.1 4.3 3.9 Scientific Notation • Way to abbreviate very large or small measurements. • Move decimal place so value of measurement is between 1 and 10. • If initial measurement is smaller than one, the exponent is negative. • If initial measurement is larger than one, the exponent is positive. Scientific Notation Analyzing Quantitative Data • Precision : • Accuracy: Analyzing Quantitative Data • Precision : • Accuracy: Accuracy vs. Precision • Accurate Results: -Compare experimental data with the actual value. -When experimental data is equal to the actual value. • Precise Results: - Comparing experimental data from several trials or from different lab groups in a class. -When experimental data is similar to one another. Exit Slip: Scientific Skills 1. Convert each measurement below to scientific notation. a.The Earth is 92,960,000 miles from the sun. b. The approximate diameter (length) of a carbon atom is 0.000000022 cm. 2. How would you explain to a friend the difference between accuracy and precision? You can include a picture. Bell Ringer: Scientific Skills 1. Convert each measurement to scientific notation. a.The Earth is 92,960,000 miles from the sun. b. The approximate diameter of a carbon atom is 0.000000022 cm. 2. How would you explain to a friend the difference between accuracy and precision (you can include an illustration)? Accuracy vs. Precision • Accurate Results: -Compare experimental data with the actual value. -When experimental data is equal to the actual value. • Precise Results: - Comparing experimental data from several trials or from different lab groups in a class. -When experimental data is similar to one another. Chemistry I-4th Block: 1/13/15 Due: • Scientific Skills worksheets(lab) • Measurement Lab-complete today Objectives: •I can convert between measurements. •I can classify data as accurate and/or precise. •I can apply scientific notation to measurements. •I can identify significant figures in a measurement. (Significant Figures Lab) Accurate Measurements Purpose: To practice taking correct measurements and apply appropriate conversions. • Every measurement has some degree of uncertainty. Depends upon the instrument used. • Determine the correct measurement for the length of paper for Ruler A and Ruler B: Accurate Measurments • Every measurement has some degree of uncertainty. Depends upon the instrument used. • Determine the correct measurement for the length of paper for Ruler A and Ruler B: Significant Figures Lab Purpose: • Take accurate measurements. • Identify and understand the importance of significant figures in a measurement. Chemistry I-4th Block: 1/14/15 Due: • Measurement Lab-place in tray Objectives: •Scientific Skills Review Quiz (interpreting and graphing data) •I can identify significant figures in a measurement. •When performing calculations with data, I can express answers to the correct degree of accuracy. Homework: • Significant Figures Lab-post qts. • Significant Figures worksheet Significant Figures Significant Figures: • The numbers directly related to an object’s measurement. • Place holders are NOT significant figures. Importance of significant figures? • Determines the degree of accuracy for a measurement. Significant Figures in Measurements 1. All non-zero numbers (1-9) are significant. Ex. 234 g = 3 significant figures (sig. figs) 2. Zeros in between nonzero numbers are significant. Ex. 2,034 g = 4 sig. figs. 3. Leading zeros (come before non-zero numbers) are NOT significant. Only serve as placeholders. Ex. 0.0234 = 3 sig. figs 4. Trailing zeros (come after non-zero numbers) are significant IF there is a decimal point in the measurement. Ex. 0.02340g = 4 sig. figs. Ex. 2,340 g = 3 sig. figs. Significant Figures in Measurements Calculating with Measurements • “Your only as good as your weakest link.” • An answer from a calculation involving measurements, can only be as accurate (good) as the weakest measurement in the calculation. Calculating with Significant Figures 1. Multiplying and Dividing: The # of sig. figs. in the answer must be equal to the # of sig. figs. in the weakest (least accurate) measurement. 2. Addition and Subtraction: The # of decimal places in the answer must be equal to the # of decimal places in the weakest measurement (least accurate). http://www.sciencegeek.net/Chemistry/Powerpoints2.shtml Calculating with Significant Figures Significant Figures Review How many significant figures are in each measurement? a. 0.054g = 2 sig. figs. b. 2.205 g= 4 sig. figs. c. 2,000g= 1 sig. fig. d. 2.0300g= 5 sig figs. Calculate each answer to the correct degree of accuracy. a. 4.025g x 0.052g x 9.20g = 1.9 g3 (2 sig. figs) b. 3.2g + 3.21g + 3g = 9 g 9g (no decimal places) Density • How do we calculate density? -Ratio of mass divided by volume of an object. -Heart! Density Lab: Class’s Analysis Lab Group Expt. Density (g/mL) Lab Group 1 10 2 11 3 12 4 13 5 14 6 15 7 16 8 17 9 18 Expt. Density (g/mL) Density Lab • Post-Lab Qts. Gallery Walk