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General, Organic, and General, Organic, and Biochemistry, 7eBiochemistry, 7e

Bettelheim,Bettelheim,

Brown, and MarchBrown, and March

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Chapter 1Chapter 1

Matter, Energy, Matter, Energy, and Measurementand Measurement

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ChemistryChemistry• Chemistry is the study of matter

• matter is anything that has mass and takes up space

• Matter can change from one form to another• in a chemical reaction (chemical change), substances

are used up and others formed in their place

Example:Example: when propane (bottled gas) burns in air, propane and oxygen are converted to carbon dioxide and water

• in a physical change, matter does not lose its identity

Example:Example: ice (solid water) melts to become liquid water; liquid water boils to become steam (gaseous water)

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Scientific MethodScientific Method

Observation

Law

Theory

Experimentation

Direct observations (facts)about the behavior of matter

Summarizes and explains a wide range of observations

A unifying principle that explains abody of observations and the laws basedon them; suggests new experiments

If experiments contradict the theory, the theory may have to be modified or discarded

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Exponential NotationExponential Notation• Used to represent very large or very small

numbers as powers of 10• Examples:

0.00002 is written as 2 x 10-5

2,000,000 is written as 2 x 106

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Metric SystemMetric System• Base units in the metric system

LengthVolumeMassTimeTemperatureEnergyAmount of matter

meter (m)liter (L)gram (g)second (s)kelvin (K)calorie (cal)mole (mol)

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Metric SystemMetric System• The most common metric prefixes

giga

mega

kilo

deci

centi

milli

micro

nano

109

106

103

10-1

10-2

10-3

10-6

10-9

G

k

d

c

m

n

Prefix ValueSymbol

M

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Metric & English SystemsMetric & English Systems• Some conversion factors

Length

1 in.1 m1 mile

===

2.54 cm39.37 in.1.609 km

Mass

1 oz1 lb1 kg

===

28.35 g453.6 g2.205 lb

Volume

1 qt1 gal1 L

===

0.946 L3.785 L33.81 fl oz

1 L = 1.057 qt

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Mass and WeightMass and Weight• Mass:Mass: the quantity of matter in an object

• mass is independent of location

• Weight:Weight: the result of mass acted upon by gravity• weight depends on location; depends on the force of

gravity at the particular location

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TemperatureTemperature• Fahrenheit (F):Fahrenheit (F): defined be setting freezing point

of water at 32°F and the boiling point of water at 212°F

• Celsius (C):Celsius (C): defined by setting freezing point of water at 0°C and boiling point of water at 100°C

• Kelvin (K):Kelvin (K): zero is the lowest possible temperature; also called the absolute scale• degree is the same size as Celsius degree• K = °C + 273

°F =95

°C + 32_ °C =59

(°F - 32)_

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Factor-Label MethodFactor-Label Method• Conversion factorConversion factor

• a ratio, including units, used as a multiplier to change from one system or unit to another

• for example, 1 lb = 463.6 g• Example:Example: convert 381 grams to pounds

• Example:Example: convert 1.844 gallons to milliliters

381 g x 1 lb453.6 g

= 0.840 lb

1.844 gal x 3.785 L1 gal

x 1000 mL1 L

= 6980 mL

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The Three States of MatterThe Three States of Matter• GasGas

• has no definite shape or volume• fills whatever container it is put into• is highly compressible

• LiquidLiquid• has no definite shape but a definite volume• is slightly compressible

• SolidSolid• has a definite shape and volume• is essentially incompressible

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DensityDensity• Density:Density: the ratio of mass to volume

• most commonly used units are g/mL for liquids and solids, and g/L for gases.

• Example:Example: If 73.2 mL of a liquid has a mass of 61.5 g, what is its density in g/mL?

d = md = densitym = massV = volumeV

d =mV

= 61.5 g73.2 mL

= 0.840 g/mL

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Specific GravitySpecific Gravity• Specific gravity:Specific gravity: the density of a substance

compared to water as a standard• because specific gravity is the ratio of two densities, it

has no units (it is dimensionless)• Example:Example: the density of copper at 20°C is 8.92 g/mL.

The density of water at this temperature is 1.00 g/mL. What is the specific gravity of copper?

= 8.928.92 g/mL1.00 g/mL

Specific gravity =

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EnergyEnergy• Energy:Energy: the capacity to do work

• may be either kinetic energy of potential energy• the calorie (cal) is the base metric unit

• Kinetic energy:Kinetic energy: the energy of motion

• KE increases as the object’s velocity increases • at the same velocity, a heavier object has greater KE

• Potential energy:Potential energy: the energy an object has because of its position; stored energy

KE =12_ mv2

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EnergyEnergy• Examples of kinetic energy are mechanical

energy, light, heat, and electrical energy• In chemistry, the most important form of potential

energy is chemical energy • chemical energy is stored in chemical substances, as

for example in foods such as carbohydrates and fats• it is given off when substances take part in chemical

reactions

• The law of conservation of energy• energy can neither be created nor destroyed• energy can only be converted from one form to another

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Heat and TemperatureHeat and Temperature• Heat is a form of energy

• heating refers to the energy transfer process when two objects of different temperature are brought into contact

• heat energy always flows from the hotter object to the cooler one until the two have the same temperature

• heat is commonly measured in calories (cal), which is the heat necessary to raise the temperature of 1 g of liquid water by 1°C

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Specific HeatSpecific Heat• Specific heat:Specific heat: the amount of heat necessary to

raise the temperature of 1 g of a substance by 1°C.

WaterIceSteamIronAluminumCopperLead

WoodGlassRockEthanolMethanolEther

1.000.480.480.110.220.0920.038

0.420.220.200.590.610.56

Acetone 0.52

Substance SubstanceSpecific Heat(cal/g •°C)

Specific Heat(cal/g •°C)

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Specific HeatSpecific Heat• The following equation gives the relationship

between specific heat, amount of heat, the mass of an object, and the change in temperature

• Example:Example: how many calories are required to heat 352 g of water from 23°C to 95°C?

Amount of heat = 1.00 calg • °C

x 352 g x (95 - 23)°C

= 2.5 x 104 cal = 25 kcal

Amount of heat = specific heat x mass x change in temperature

= SH x m x (T2 - T1)

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End End Chapter 1Chapter 1

Matter, Energy, and MeasurementMatter, Energy, and Measurement