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Chapter 1

- Chemistry and
- Measurement

Chemistry

- What is it?
- Why do we study it?

Physical States

- solid
- fixed volume and shape

Physical States

- solid
- fixed volume and shape
- liquid
- fixed volume
- shape of container, horizontal top surface

Physical States

- solid
- fixed volume and shape
- liquid
- fixed volume
- shape of container, horizontal top surface
- gas
- takes shape and volume of container

Physical States

- solid
- fixed volume and shape
- liquid
- fixed volume
- shape of container, horizontal top surface
- gas
- takes shape and volume of container
- liquid crystal
- some characteristics of solid and some of liquid

states

Modern Chemistry A Brief Glimpse

Exploring the Nanoworld

To order a kit (Special introductory price, 24

shipped to US addresses) contact the Institute

for Chemical Education

Air Bags How Do They Work?

http//whyfiles.news.wisc.edu/032air_bag/how_work.

html

Matter

- has mass
- mass vs. weight
- occupies space

Scientific Method

- Experiment
- Results
- Hypothesis
- further experiments
- refine the hypothesis
- Theory
- experiments to test the theory
- refine the theory

Law of Conservation of Mass

- In an ordinary chemical reaction matter is

neither created nor destroyed. - The sum of the masses of the reactants equals the

sum of the masses of the products.

Properties of Matter

- Extensive Property
- depends on specific sample under investigation
- examples
- mass and volume

- Intensive Property
- identical in all samples of the substance
- examples
- color, density, melting point, etc.

Physical Property

- one that can be observed without changing the

substances present in the sample - changes in physical properties of substances

Chemical Property

- the tendency to react and form new substances

Chemical Reaction

- reactants undergo chemical change to produce

products - sucrose ---gt carbon water
- reactant products

Chemical Reaction

- Reactions are indicated by
- evolution of a gas
- change of color
- formation of a precipitate

Law of Definite Proportions

- All samples of the same pure substance always

contain the same elements in the same proportions

by weight

Pure Substances

- Elements
- Compounds

Mixtures

- Heterogeneous
- uneven texture
- Homogeneous (Solution)
- sample uniform throughout

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Separation of Mixtures

- filtration
- distillation
- chromatography

Filtration

- separate solids by differences in melting points
- separate solids by differences in solubility

(fractional crystallization) - mechanical separation such as in Fig. 1.11 page

13.

Distillation

- separation by differences in boiling point

(fractional distillation) - distillate
- distillation
- fractionating column - part of apparatus where

separation occurs

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Chromatography

- liquid-column
- paper
- thin-layer (TLC)
- gas
- HPLC
- electrophoresis (DNA mapping)

Column Chromatography

Paper Chromatography of Inks

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Uncertainty in Measurements

- Accuracy
- closeness to true value
- vs
- Precision
- reproducibility

Accurate and/or Precise?

Accurate and/or Precise?

Significant Figures

- Rules for determining which digits are

significant - All non-zero numbers are significant
- Zeros between non-zero numbers are significant
- Zeros to the right of the non-zero number and to

the right of the decimal point are significant - Zeros before non-zero numbers are not significant

Significant FiguresExamples

- Railroad Track Scale
- 70,000,000 g
- 500,000 g
- 7.00 x 107 g (scientific notation)
- 7.00 E7 g (engineering notation)
- 3 significant figures

Significant FiguresExamples

- Regular Lab Balance
- 1,000 g 0.1 g
- 1.0000 x 103 g
- 5 sig. fig.
- 400 g 0.01 g
- 4.0000 x 102 g
- 5 sig. fig.
- 100 0.001 g
- 1.00000 x 102 g
- 6 sig.fig.

Rules for MathematicsMultiplication and Division

- For multiplication and division, the number of

significant figures used in the answer is the

number in the value with the fewest significant

figures.

(2075)(14) ---------------- (144)

2.0 x 102

4 sig. fig.

gt

2 sig.fig.

3 sig. fig.

2 sig. fig.

Rules for MathematicsAddition and Subtraction

- For addition and subtraction, the number of

significant figures used in the answer is

determined by the piece of data with the fewest

number decimal places. - 4.371
- 302.5
- --------
- 306.8

Rules for MathematicsAddition and Subtraction

- For addition and subtraction, the number of

significant figures used in the answer is

determined by the piece of data with the fewest

number decimal places. - 4.371
- 302.5
- --------
- 306.8

Rules for MathematicsAddition and Subtraction

- For addition and subtraction, the number of

significant figures used in the answer is

determined by the piece of data with the fewest

number decimal places. - 4.371 (I truncate extra

data) - 302.5
- --------
- 306.8

Exact Numbers

- conversion factors
- should never limit the number of significant

figures reported in answer - 12 inches 1 foot

Round Off

- Chemistry is an inexact science
- all physical measurements have some error
- thus, there is some inexactness in the last digit

of any number - use what ever round-off procedure you choose
- reasonably close answers accepted

Measurement and Units

- length - meter
- volume - liter
- mass - gram

Important Metric Unit Prefixes

- deci -- 1/10
- centi -- 1/100
- milli -- 1/1000
- nano -- 1/1,000,000,000
- kilo -- 1000

Liter

- 1 liter 1 decimeter3
- by definition
- where
- 1 decimeter 10 centimeters
- therefore
- 1 liter (10 centimeters)3
- or
- 1 liter 1000 cm3 1000 mL

Millimeter

- 1 millimeter 1/1000 meter
- 1000 millimeter 1 meter
- 1000 mm 1 m

Nanometer

- 1 nanometer 1/1,000,000,000 meter
- 1,000,000,000 nanometer 1 meter
- 1,000,000,000 nm 1 m

Liter

- 1 liter 1 decimeter3
- 1 liter 1000 milliliters
- 1 L 1000 mL
- 1 mL 0.001 L

Milligram

- 1 milligram 1/1000 gram
- 1 mg 0.001 g

Kilogram

- 1 kilogram 1000 gram
- 1 g 0.001 kg
- 1 mg 0.000001 kg
- 1 kg 1,000,000 mg

Conversion of Units

- 1 in 2.54 cm

Temperature

- Scales
- Fahrenheit
- Rankin
- absolute scale using Fahrenheit size degree
- Celsius
- Kelvin
- absolute scale using Celsius size degree

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Comparison of Temperature Scales

Temperature Relationships

- C 100/180 (F - 32)
- F (180/100)C 32
- K C 273.15
- - 40o F - 40o C

- If the temperature of the room goes from 20

degrees C to 40 degrees C, the ambient thermal

energy - doubles
- is halved
- increases by less than 10

Density

- Mass per unit of volume gt d m/V
- Mass equals volume times density gt m Vd
- Volume equals mass divided by density gt V m/d

Problem Solving by Factor Label Method

- state question in mathematical form
- set equal to piece of data specific to the

problem - use conversion factors to convert units of data

specific to problem to units sought in answer

Example

- How many kilometers are there in 0.200 miles?

Example

- How many kilometers are there in 0.200 miles?
- state question in mathematical form
- km

Example

- How many kilometers are there in 0.200 miles?
- set equal to piece of data specific to the

problem - km 0.200 miles

Example

- How many kilometers are there in 0.200 miles?
- use conversion factors to convert units of data

specific to problem to units sought in answer - km (0.200 miles)
- (5280 ft/mile)

Example

- How many kilometers are there in 0.200 miles?
- cancel units
- km (0.200 miles)
- (5280 ft/mile)

Example

- How many kilometers are there in 0.200 miles?
- add another conversion factor
- km (0.200)(5280 ft)
- (12 in/ft)

Example

- How many kilometers are there in 0.200 miles?
- cancel units
- km (0.200)(5280 ft)
- (12 in/ft)

Example

- How many kilometers are there in 0.200 miles?
- km (0.200)(5280)(12 in)

Example

- How many kilometers are there in 0.200 miles?
- add still another conversion factor
- km (0.200)(5280)(12 in)
- (2.54 cm/in)

Example

- How many kilometers are there in 0.200 miles?
- cancel units
- km (0.200)(5280)(12 in)
- (2.54 cm/in)

Example

- How many kilometers are there in 0.200 miles?
- km (0.200)(5280)(12)(2.54 cm)

Example

- How many kilometers are there in 0.200 miles?
- add still another conversion factor
- km (0.200)(5280)(12)(2.54 cm)
- (1 m/100 cm)

Example

- How many kilometers are there in 0.200 miles?
- cancel units
- km (0.200)(5280)(12)(2.54 cm)
- (1 m/100 cm)

Example

- How many kilometers are there in 0.200 miles?
- km (0.200)(5280)(12)(2.54)
- (1 m/100)

Example

- How many kilometers are there in 0.200 miles?
- add still another conversion factor
- km (0.200)(5280)(12)(2.54)
- (1 m/100)(1 km/1000 m)

Example

- How many kilometers are there in 0.200 miles?
- cancel units
- km (0.200)(5280)(12)(2.54)
- (1 m/100)(1 km/1000 m)

Example

- How many kilometers are there in 0.200 miles?
- km (0.200)(5280)(12)(2.54)
- (1/100)(1 km/1000)

Example

- How many kilometers are there in 0.200 miles?
- solve mathematics
- km (0.200)(5280)(12)(2.54)
- (1/100)(1 km/1000)
- 0.322 km
- 3 sig. fig.

Example

- How many kilometers are there in 0.200 miles?
- solve mathematics
- km (0.200)(5280)(12)(2.54)
- (1/100)(1 km/1000)
- 0.322 km
- 3 sig. fig. exact numbers