welcome to chemistry i. chemistry i-4 th block: 1/6/14 due: syllabus signed-place in tray...
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Welcome to Chemistry I
Chemistry I-4th 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. Make the correct unit conversions.
a. 0.0079 L = _____mL
b. 500 g = ____kg
c. How many meters are in 22.5 in?
d. How many ft are in 13.5 km?
2. 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 Skills1. 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 MeasurementsPurpose: 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 LabPurpose:
• 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 FiguresSignificant 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 Measurements1. 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 AnalysisLab Group Expt. Density
(g/mL)Lab Group Expt. Density
(g/mL)
1 10
2 11
3 12
4 13
5 14
6 15
7 16
8 17
9 18
Density Lab
• Post-Lab Qts.
Gallery Walk