CHEM 1123Survey of General,

Organic, and Biochemistry

Dr. Fabiola Janiak-Spensfspens@occc.edu

Website: www.occc.edu/fspensOffice: 1D6A

Office Hours: T & Th: 9 - 11 amM & W: 2 – 3:30 pm

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CHEMICALS are everywhere!

Which ingredients are chemicals?

Cinnamon Burst Cheerios Ingredient List2

More Chemicals

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Chemicals in ToothpasteChemical = a substance that has the same composition and

property regardless of where it is found

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How to be successful in this class

Be prepared: look at syllabus, read assigned chapter, do examples in text, do suggested homework.

Come to class.

Do quizzes.

Form study groups, make use of internet resources, use tutors in physical science center.

Talk to me before it gets to be too late.

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Unit 1Measurements and

Dimensional Analysis

Reading Assignment:

Chapter 1

Chapter 2: sections 2.1 and 2.4 only

Chapter 3: section 3.1 only

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MeasurementsMeasurement: a number followed by a unit

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Units of MeasurementThe metric system or SI (international system) is

•a decimal system based on 10.

•used in most of the world.

•used everywhere by scientists.

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Length

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Metric and SI unit: meter (m)1 m = cm 100 1 m = yd1.09

Measured using meterstick, yardstick.

Volume

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Metric unit: liter (L), SI unit: cubic meter (m3)1 L = qt1.06 1 L = mL1000

In Lab: measure volumes using graduated cylinders.

Mass

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Metric unit: gram (g), SI unit: kilogram (kg)

1 kg = g1000 454 g = lb1

Weight = measure of gravitational pull on an object.

Mass = measure of quantity of material contained in an object

Thus: measure mass not weight!

The Standard Kilogram

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The standard kilogram is housed at the International Bureau of Weights and Standards near Paris. NIST (= National Institute of Standards and Technology) maintains an official copy.

Temperature

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Metric unit: Celsius (°C), SI unit: Kelvin (K)

Water freezes at °C and boils at °C. 0 100

0 °C = °F32

Time

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Metric and SI unit: second (s)

The NIST F-1 atomic clock is accurate to within one second every thirty million years.

Check SI Units

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Identify the measurement that has an SI unit. A. John’s height is

1) 1.5 yd. 2) 6 ft. 3) 2.1 m.

B. The race was won in1) 19.6 s. 2) 14.2 min. 3) 3.5 hr.

C. The mass of a lemon is1) 12 oz. 2) 0.145 kg. 3) 0.6 lb.

D. The temperature is1) 85C. 2) 255 K. 3) 45F.

Scientific Notation

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Used to write very large or very small numbers.

= 1x 10 x 10 x 10 x 10 x 10 hairs= 100,000 hairs

= 8 x x x x x x 110

110

110

110

110

110

= 0.000 008 m

Scientific notation numbers

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2400 m = 2.4 x 103 m

Coefficient

= 1 9,Never 0 or ≥ 10

Power of 10

Scientific Notation: Large numbers

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For any number greater than 1: power of 10 is positive.

2400 m

Each place moved counts as one 10, have moved 3 times.

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Scientific Notation: small numbers

For any number smaller than 1: power of 10 is negative.

0.00086 g

Each place moved counts as one 10, have moved 4 times.

Scientific Notation

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Scientific Notation

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Check

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Select the correct scientific notation for each.

A. 0.000 0081) 8 x 106 2) 8 x 10-6 3) 0.8 x 10-5

B. 72 0001) 7.2 x 104 2) 72 x 103 3) 7.2 x 10-4

Check

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Write each as a standard number.

A. 2.0 x 10-2

1) 200 2) 0.0020 3) 0.020

B. 1.8 x 105 1) 180 000 2) 0.000 018 3) 18 000

Check

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Is this a number in scientific notation?

1.55.0 x 103 m

2.145.0 x 10-5 g

= 55000 m = 5.5 x 104 m

= 0.00145 g = 1.45 x 10-3 g

Measured Numbers

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Obtained using a measuring tool.

Measured Numbers and Significant Figures

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4.5 cm

4.55 cm

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Measured Numbers and Significant Figures

3 cm or 3.0 cm

Measured numbers consist of:Certain digit(s) and one estimated digit

Measured Numbers and Significant Figures

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4.5 cm

4.55 cm

Certain digits vs estimated digits

Significant Figures (SF) in measured numbers

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Count number of digits that are certain plus the one estimated one

= number of SF of the measured number

38.15 cm

5.6 ft

65.5 g

122.55 m

Measurement # of SF4

2

3

5

Significant Figures (SF) in measured numbers

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Zeros are tricky, have rules!

56000 g

77089 g

0.000568 m

0.000507m

0.06700 g

Trailing zeros, no decimal point, zeros don’t count.

Sandwiched zero, does count.

Leading zeros, decimal point, zeros don’t count.

Leading zeros, decimal point, zeros don’t count.Sandwiched zero, does count.

Leading zeros, decimal point, zeros don’t count.

Trailing zeros, decimal point, zeros count.

2 SF

5 SF

3 SF

3 SF

4 SF

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Check

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A. Which answer(s) contain 3 significant figures? 1) 0.4760 2) 0.00476 3) 4.76 x

103

B. All the zeros are significant in

1) 0.00307 2) 25.300 3) 2.050 x 103

C. The number of significant figures in 5.80 x 102 is 1) one 3) two 3) three

Exact Numbers

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Obtained by counting or by definition.No SF associated with exact numbers!

Check

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Classify each of the following as (1) exact or (2) measured numbers.

A. Gold melts at 1064°C.

(2) A measuring tool is required.

B. 1 yard = 3 feet

(1) This is a defined relationship.

C. The diameter of a red blood cell is 6 x 10-4 cm.

(2) A measuring tool is used to determine length.

D. There are 6 hats on the shelf.

(1) The number of hats is obtained by counting.