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