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