What is Chemistry?

What is Chemistry?

Chemistry is…

The study of all substances and the changes they undergo, central science because it overlaps many other sciences

Who Uses Chemistry?

Who Uses Chemistry?

If you think the answer consists of a variety of scientists, you have a lot to learn.

Who Uses Chemistry?These people all use chemistry on a daily basis…

Forensic examiners Perfume makers Dye makers Medical researchers Engineers Biologists Agriculture workers Artists Archaeologists Ecologists Waste water treatment workers Cooks Textile manufacturers Beauticians And many more…

Lab Equipment

Goggles

Goggles are meant to protect your eyes and Goggles are meant to protect your eyes and therefore need to be worn appropriately. If you wear therefore need to be worn appropriately. If you wear glasses, you still need to wear goggles.glasses, you still need to wear goggles.

Beaker

Beakers hold solids or liquids that will not release Beakers hold solids or liquids that will not release gases when reacted or are unlikely to splatter if gases when reacted or are unlikely to splatter if stirred or heated.stirred or heated.

Graduated Cylinder

A graduated cylinder is used to measure A graduated cylinder is used to measure volumes of liquids. This is a better choice volumes of liquids. This is a better choice for measuring volume than beakers or for measuring volume than beakers or flasks.flasks.

Erlenmeyer Flask

Erlenmeyer flasks hold solids or liquids that may Erlenmeyer flasks hold solids or liquids that may release gases during a reaction or that are likely to release gases during a reaction or that are likely to splatter if stirred or heated.splatter if stirred or heated.

Weighing Boat

Weighing boats are used to weigh solids that will be transferred Weighing boats are used to weigh solids that will be transferred to another vessel.to another vessel.

Test Tube Racks

Test tube racks are for holding and organizing test tubes on the laboratory counter.Test tube racks are for holding and organizing test tubes on the laboratory counter.

Test Test TubesTubes 13 x 100 mm test tubes13 x 100 mm test tubes

10 x 75 mm test tubes10 x 75 mm test tubes

IgnitionIgnitiontubetube

A test tube is useful for holding liquids and for A test tube is useful for holding liquids and for containing small chemical reactions.containing small chemical reactions.

Test Tube Holder

A test tube holder is useful for holding a test A test tube holder is useful for holding a test tube which is too hot to handle.tube which is too hot to handle.

Beaker Tongs

Beaker tongs are used to move beakers Beaker tongs are used to move beakers containing hot liquidscontaining hot liquids

Crucible Tongs

For handling hot crucibles; also used to pick up other hot For handling hot crucibles; also used to pick up other hot objects. objects. NOTNOT to be used for picking up beakers! to be used for picking up beakers!

Test Tube BrushesTest tube brushes are used to clean test tubes and Test tube brushes are used to clean test tubes and graduated cylinders.graduated cylinders.

Forcing a large brush into a small test tube will often Forcing a large brush into a small test tube will often break the tube.break the tube.

Rubber StoppersRubber stoppers are used to close containers to avoid Rubber stoppers are used to close containers to avoid spillage or contamination.spillage or contamination.

Containers should never be heated when there is a stopper Containers should never be heated when there is a stopper in place.in place.

Spot Plates/Well PlatesSpot plates are used when we want to perform many small Spot plates are used when we want to perform many small scale reactions at one time. scale reactions at one time.

Glass Stir Rod

A glass rod is used to manually stir solutions.A glass rod is used to manually stir solutions.

Medicine Dropper

A medicine dropper is used to transfer a small A medicine dropper is used to transfer a small volume of liquid (less than one mL). In class, we volume of liquid (less than one mL). In class, we often use disposable pipettes instead of droppers.often use disposable pipettes instead of droppers.

Litmus Paper

RedRed litmus paper is used to identify bases. litmus paper is used to identify bases.

BlueBlue litmus paper is used to identify acids. litmus paper is used to identify acids.

Forceps

Forceps (or tweezers) are used to pick up small objects.Forceps (or tweezers) are used to pick up small objects.

Funnel

A funnel is used to aid in the transfer A funnel is used to aid in the transfer of liquid from one vessel to another.of liquid from one vessel to another.

Wash Bottle

A wash bottle has a spout that delivers a wash solution A wash bottle has a spout that delivers a wash solution to a specific area. Distilled water is the only liquid that to a specific area. Distilled water is the only liquid that should be used in a wash bottle.should be used in a wash bottle.

SpatulasSpatulas are used to dispense solid chemicals from their Spatulas are used to dispense solid chemicals from their containers. containers.

Chemicals should never be transferred with your bare Chemicals should never be transferred with your bare hands.hands.

ScoopulasScoopulas are used to dispense solid chemicals from Scoopulas are used to dispense solid chemicals from their containers. their containers.

Chemicals should never be transferred with your bare Chemicals should never be transferred with your bare hands.hands.

http://en.wikipedia.org/wiki/File:Two_Scoopulas.jpg

StrikersStrikers are used to light Bunsen burners. Strikers are used to light Bunsen burners.

The flints on strikers are expensive. Do not operate the The flints on strikers are expensive. Do not operate the striker repeatedly just to see the sparks!striker repeatedly just to see the sparks!

Bunsen Burner

Bunsen burners are used for the heating of nonvolatile Bunsen burners are used for the heating of nonvolatile liquids and solids.liquids and solids.

Crucible

Crucibles are used for heating certain solids, to very Crucibles are used for heating certain solids, to very high temperatures.high temperatures.

Clay Triangle

The clay triangle is used as a support for porcelein The clay triangle is used as a support for porcelein crucibles when being heated over a Bunsen burner.crucibles when being heated over a Bunsen burner.

Ring stands and their Components

Ring stands are a safe and convenient way to perform reactions Ring stands are a safe and convenient way to perform reactions that require heating using a Bunsen burner.that require heating using a Bunsen burner.

Ring stands and their Components

Iron Rings

Iron rings connect to a ringstand and provide a stable, Iron rings connect to a ringstand and provide a stable, elevated platform for the reaction.elevated platform for the reaction.

Ringstands and their ComponentsUtility Clamps

Utility clamps are used to secure test tubes, distillation Utility clamps are used to secure test tubes, distillation columns, and burets to the ringstand.columns, and burets to the ringstand.

Ringstands and their ComponentsWire Gauze

Wire gauze sits on the iron ring to provide a place to stand a Wire gauze sits on the iron ring to provide a place to stand a beaker. beaker.

On older wire gauze, the white material is asbestos!On older wire gauze, the white material is asbestos!

Lab IssuesLab Safety• Flinn contract

• Broken glass bucket

• Fire extinguisher

• Eye wash

Scientific NotationWriting

• Format: M x 10x

–M must be less than 10

–M must be greater than or equal to 1

–x can be any whole number

Scientific NotationSample Numbers to Write

• 450

• 3,000,000

• 0.014

• 0.000 000 08

MeasurementTwo types of measurements

• Qualitative – present regardless of amount

Examples – color, taste, luster, density, etc.

MeasurementTwo types of measurements

• Quantitative – based on amount

Examples – mass, length, area, volume, etc.

Metric UnitsIn science, we use the metric

system because it is an international system (unlike the English system that is rarely used). These units have precise definitions.

Metric UnitsSI Base units• Length – meter, m• Mass – kilogram, kg• Time – second, s• Count – mole, mol• Temperature – kelvin, KSometimes, the base units are

combined to create other units

Measurement

Derived units• Area – square meter, m2

• Volume – cubic meter, m3

• Force – newton, N• Pressure – pascal, Pa• Energy – joule, J• Power – watt, W• Voltage – volt, V• Frequency – hertz, Hz• Electric charge – coulomb, C

MeasurementMetric PrefixesSometimes SI units aren’t

convenient for object being measured so we use metric prefixes to indicate smaller or larger units of measurement.

MeasurementMetric PrefixesSometimes SI units aren’t convenient for object being measured so we use

metric prefixes to indicate smaller units of measurement.• mega M 1,000,000 1 x 106

• Kilo k 1,000 1 x 103

• hecto h 100 1 x 102

• deka dk 10 1 x 101

• -unit- 1 1 x 100

• deci d 0.1 1 x 10-1

• centi c 0.01 1 x 10-2

• milli m 0.001 1 x 10-3

• micro 0.000,001 1 x 10-6

• nano n 0.000,000,001 1 x 10-9

• pico p 0.000,000,000,001 1 x 10-12

MeasurementMetric PrefixesSometimes SI units aren’t convenient for object being measured so we use metric prefixes to indicate smaller units of

measurement.• mega M 1,000,000 106

• kilo k 1,000 103

• hecto h 100 102

• deka dk 10 101

• -base- 1 100

• deci d 0.1 10-1

• centi c 0.01 10-2

• milli m 0.001 10-3

• micro 0.000,001 10-6

• nano n 0.000,000,001 10-9

• pico p 0.000,000,000,001 10-12

The symbols for these prefixes can be added to the beginning of any SI unit to indicate smaller or larger measurements.

Precision vs. Accuracy

What is precision?how well measurements agree

with each other

Example: 3 measurements taken of a mass give 1.00 g, 1.02 g, & 1.01 g

Precision vs. Accuracy

What is accuracy?how well measurements agree

with an accepted standard

Example: 3 measurements taken of a

mass give 1.00 g, 1.02 g, & 1.01 g, accepted value = 1.01 g

Percent, Percent Error, Ratios

How to express results…Percent =

obtained × 100= _%total

–May be given mixture and asked to calculate percent of one part


How to express results…Percent

Example: A sample is 750 g. 400 g of that 750 g are lead. What is the percent of lead?

Percent, Percent Error, RatiosHow to express results…Percent error =

(measured – accepted) × 100accepted

• Can be + or -, depends on whether measurement was more or less than accepted value


How to express results…Percent error

Example: An object was measured 45 cm. The actual value was 45.5 cm. What was the percent error?


How to express results…Ratio• speed = dist/time• Population density = pop/area• Density = m/v• The previous equations may be

rearranged to solve for any of the variables.


How to express results…Ratio• speed = dist/time• Population density = pop/area• Density = m/v• The previous equations may be rearranged to solve for any of the variables.

• Example 1: Find the density of iron with mass 1.23 kg and volume 156 cm3.


How to express results…Ratio• speed = dist/time• Population density = pop/area• Density = m/v• The previous equations may be rearranged to solve for any of the variables.• Example 1: Find the density of iron with mass 1.23 kg and volume 156 cm3.

• Example 2: A liquid has mass 30.6 g and volume 53.3 mL. What is the density?


How to express results…Ratio• speed = dist/time• Population density = pop/area• Density = m/v• The previous equations may be rearranged to solve for any of the variables.• Example 1: Find the density of iron with mass 1.23 kg and volume 156 cm3.• Example 2: A liquid has mass 30.6 g and volume 53.3 mL. What is the density?

• Example 3: Iron has density 7.86 g/ cm3. Could a metal block of mass 12.8 g and volume 2.56 cm3 be iron?


How to express results…Ratio• speed = dist/time• Population density = pop/area• Density = m/v• The previous equations may be rearranged to solve for any of the variables.• Example 1: Find the density of iron with mass 1.23 kg and volume 156 cm3.• Example 2: A liquid has mass 30.6 g and volume 53.3 mL. What is the density?• Example 3: Iron has density 7.86 g/ cm3. Could a metal block of mass 12.8 g and volume 2.56 cm3 be iron?

• Example 4: Find mass of 200. cm3 of air if the density is 0.0013 g/cm3


How to express results…Ratio• speed = dist/time• Population density = pop/area• Density = m/v• The previous equations may be rearranged to solve for any of the variables.• Example 1: Find the density of iron with mass 1.23 kg and volume 156 cm3.• Example 2: A liquid has mass 30.6 g and volume 53.3 mL. What is the density?• Example 3: Iron has density 7.86 g/ cm3. Could a metal block of mass 12.8 g and volume 2.56 cm3 be iron?• Example 4: Find mass of 200. cm3 of air if the density is 0.0013 g/cm3

• Example 5: What is the volume of 160.0 g iron if density is 7.86 g/cm3

Density• A copper penny has a mass of 3.1

g and a volume of 0.35 cm3. What is the density?

Density• A graduated cylinder contains

44.2 mL of water. A 48.6 g piece of metal is dropped into the cylinder and the water rises to the 51.3 mL mark. What is the density of the metal?

Density• A plastic ball with a volume of

19.7 cm3 has a mass of 15.8 g. What is the density? If the density of gasoline is between 0.66 g/cm3 and 0.69 g/cm3, will the ball float or sink in a container of gasoline?

Density• The density of silver at 20 °C is

10.5 g/cm3. What is the volume of a 68 g bar of silver?

Elements, compounds & mixtures

Elements & Compounds• Element – substance that

cannot be separated into simpler substances by chemical change, organized in Periodic Table


Elements & Compounds• Element – substance that cannot be separated into simpler substances by chemical change, organized in

Periodic Table

• Compound – 2 or more elements combined by chemical change


Pure Substance or Mixture• Pure Substance – has

unique set of chemical & physical properties (includes all elements and compounds)


Pure Substance or Mixture• Pure Substance – has unique set of chem & phys properties (includes all elements and compounds)

• Mixture – blend of 2 or more substances (not combined chemically)


Pure Substance or Mixture• Pure Substance – has unique set of chem & phys properties (includes all elements and compounds)

• Mixture – blend of 2 or more substances (not combined chemically)

Types:•Heterogeneous – visibly different parts

•Homogeneous – no visibly different parts


Mixture Separation•Filtration – often used for heterogeneous mixes


Mixture Separation• Filtration – often used for heterogeneous mixes (not homogeneous)

•Distillation – heat liquid & drive it off, leaving solid (or liquid w/ higher boiling point)


Mixture Separation• Filtration – often used for heterogeneous mixes• Distillation – heat liquid & drive it off, leaving solid (or liquid w/ higher boiling point)

•Crystallization – evaporate liquid, leaving solid


Mixture Separation• Filtration – often used for heterogeneous mixes• Distillation – heat liquid & drive it off, leaving solid (or liquid w/ higher boiling point)• Crystallization – evaporate liquid, leaving solid

•Chromatography – flow solution along stationary source

Documents

What is Chemistry?