Chemistry in the

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22 Φεβ 2014 (πριν από 3 χρόνια και 3 μήνες)

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Chemistry in the
Community

Safety


Always use small containers easily handled.


Never mix chemicals without teacher’s
permission.


Add acid to water, never reverse.


Work tray will help contain spills.


When selling chemicals, only if directed to do so,
hold away from face and wave scent towards
nose.


Read all labels.


Hold coin
-
top of stoppers between fingers and
replace as soon as possible.


Notify teacher to clean up spills.


Make sure hose fits securely and has no
cracks.


Only heat open containers.


Always use tongs, never bare hands.


Check glass ware for scars or cracks.


Never shake thermometer.


If thermometer breaks, let teacher know.


Use thermometer only in temp range
recommended.


Lay thermometer down on towel to cool
away from lab.


No loose sleeves or clothes in lab.


Fuzzy sweaters can easily start on fire.


No open shoes, leather closed shoes.


ALWAYS WEAR SAFETY GLASSES!


Fabrics strong and sturdy


Lab apron.


Long pants.


Tie long hair back.


Take off jewelry.


No fooling around.


Stand
on stool if needed.


Immediate medical attention after any cut.



Rinse eyes for 15 minutes if you get chemicals in
them.


Rinse chemicals from hands


Get naked for shower
.



Put out fire in safety shower.


No eating or drinking in lab.

Defined:

The process of clarifying water in order to
make it suitable for release into the environment, or for
making it fit for human consumption (potable).

Water quantity has its limits:
Water supplies on
the earth are finite. Current distribution of water is as
follows


Oceans (saltwater) =


97.2%


FRESH Water = 2.8%

Glaciers =


2.11%



Rivers = .0001%



Lakes = .009%



Atmosphere = .001%



Groundwater = .62%

Water Treatment


*
With
fresh water supplies being
so small, water quality is important.
This means that water must be
cleaned before we use it, and before
discharging into the environment it
must be cleaned.

PROCESS OF WATER TREATMENT

Definition:

To
clarify
water;
that is to remove
suspended
material,
is critical to improving
the water’s quality.

Stages

of

Water

Treatment

1.
Large Solid Removal:

A screen or grate is used to
separate large rocks, trees, etc… from water

2.
Coagulation, Flocculation, and Sedimentation:

A
chemical (coagulant) that will cause large suspended
particles to form clumps (
floc
) is added to water. This
floc

will float or settle out (sedimentation)

3.

Filtration:

Percolation of water downward through
porous material and suspended materials get caught and
water passes through. Filter Medial includes sand,
gravel, clay, charcoal and screens. Separation works
with large pores collecting large particles, with smaller
pores, collecting small particles. During filtration,
particles may adhere/stick (adsorption) to filter media.

1.
Disinfection:

The addition of chemicals, usually chlorine
to water effort to kill pathogens/microbes/bacteria.

2.
Dissolved Solids:

These materials will stay with the water
because they are dissolved solids in water. Conductivity is
a measure of the ability of water to conduct an electrical
current. Under most conditions dissolved materials are
not removed during water treatment.

3.
*
To
understand
Riverwood’s

Problem: The people of
Riverwood

must understand the property and
behavior of water.

PHYSICAL PROPERTIES OF WATER

1.
Water is clear, odorless, and tasteless. Any color,
taste or smell is given to water by some outside
source.

2.
Water is capable of dissolving many different
substances. It is defined as the
universal solvent.

Any substance dissolved in water is said to be in an
aqueous solution.

3.
*

Electrolytes:

Act as a conductor of electricity


4. Water
is a liquid at room temperature

5. Water
has a density of
1g/
mL
.

This doesn’t change
much as water changes phases. The only unique
condition occurs when water freezes. Its behavior at 0
°

C is unique to water and nothing else. It expands.

6. Water
has a narrow range of temperature between
its freezing/melting point and boiling point (0
-
100
°

C)

7. Polluted
water is a mixture. This means some
materials are dissolved in water forming a solution.
While others are not dissolved and exist in suspension
or as a colloid.

Distillation Apparatus


MOLECULAR WATER

1.
Composed of
elements

hydrogen and oxygen

2.
Hydrogen and oxygen combine in a
2:1
ratio

3.
As water is formed, each hydrogen atom gives
up one electron and the oxygen accepts 2
electrons

4.
Molecular formula for water is
H₂O

H

H

O

105
°

Polar

Molecule


Structural formula for water is:

Because water has positive and negative
poles, this allows for the formation of
some new bonds too. These bonds are
called
HYDROGEN BONDS.
Hydrogen
Bonds are weak forces that allow two
water molecules to be attracted to each
other.
(See Figure)

The outcomes of hydrogen bond formation are the
following:

1.
Causes water to behave differently than other materials

*Water expands when it becomes ice

2.
Requires that water absorbs more energy to change
phases(states)

*Water will absorb or release huge amounts of heat.
*Temp will remain constant

3.
Allows water to remain a liquid most of the time

O
°

C = Freezing/Melting,

0
-
100
°

C= Liquid,

100
°

C = Boiling Point

**As matter changes phases (states), heat energy must be absorbed

Solid



Liquid



Gas


Heat Gain



Heat Gain


KE Increase



KE increase


Temp Increase



Temp Increase




*At the
phase change
, that is the time when a solid is converting to a
liquid and a liquid is converting into a gas,
Kinetic Energy remains
unaffected
. Particle motion doesn’t change; as a result the
temperature
doesn’t change
. The only factor that changes is the
Potential energy
.

Potential Energy must increase to break hydrogen bonds!

TEMPERATURE:

Measure of
average kinetic energy
of particles in motion, therefore temperature doesn’t
change during phase change. There is
no change
in the
kinetic energy of the material (water).


Boiling

Boiling

Condensing

Solid

/ Melting Point

Boiling Point

Liquid

-
50
°

C

0
°

C

100
°

C

150
°

C

Heat Added

Heating
-

Cooling Curves


G
a
s





Freeze

Gas

Temperature (
o
C
)

Energy Added

Phase Change Measurements:

1.
Latent Heat of Fusion
:

A measure of heat needed to melt one gram
of matter (water) to a liquid.



For water this is a lower volume, because hydrogen bonds are
needed to be broken; therefore less energy.

2.
Latent Heat of Vaporization
:

A measure of heat needed to vaporize
one molecule of matter (water) to a gas.



More hydrogen bonds need to be broken; therefore this value is
greater for water.

Remember at both melting and vaporization

TEMPERATURE DOESN’T CHANGE!!!!!!!!!!

3.
Specific Heat
:

The amount of energy need to raise the temperature
of one gram of a substance one degree Celsius
.

Ground Water

-
Ground Water can be defined as water found in cracks and pores
of a rock below the earth’s surface


-
The rock through which water can be stored and transmitted (flows,
or is pumped out of) is identified as an aquifer.


Aquifers can be described by the following conditions:

1. Dimensions:



-
Vertical Dimension: Depth below ground level. Range from 0 feet
-
100’s of feet.


-
Horizontal Dimension: Width of the water table. Ranges from 100’s of miles.

2. Production:

Gallons per mile.

3. Age:

Period of time the water has been present in the aquifer (days or years.)

4. Movement:



-
Vertical Movement: Recharge of ground water.


-

Horizontal Movement: water flows down hill’ water will follow contour of the land.

Ground Water Terminology



Water Table:

The top of an unconfined aquifer; indicates the level
below which soil and rock are saturated with water.


Confined Aquifer:

An aquifer that is bounded above and below by non
permeable layer that transmits water significantly more slowly that an
unconfined aquifer.

The water will rise above the top of the aquifer because the confine
aquifer is under pressure.


Unconfined Aquifer:

An aquifer in which the upper boundary is the
top of the water table.


Permeable Layer:

Portion of aquifer that contains rock material that
does not allow water to penetrate freely.

Ground Water Terminology


Impermeable Layer:

Portion of aquifer that contains rock
material that does not allow water to penetrate; often forms
the base of unconfined aquifers and the boundaries for
confined aquifers.


Zone Of Saturation:

The part of water bearing formation in
which all spaces between soil particles and in rock structures
are filled with water.


Zone Of Aeration:

Portion of unconfined aquifer above the
water table where the pore spaces among soil particles and
rock formations are filled with air.

Aquifers Of Wisconsin


Sand And Gravel Aquifer

1.
Covers most of Wisconsin except the south west part of the state
(
Driftless

Area
.)

2.
Created when the glaciers carried debris across the state and
ancient rivers deposited material.

3.
Excellent source of water and is used extensively for irrigation.

4.
Because of its nearness to the surface it can easily be
contaminated.

Aquifers Of Wisconsin


Eastern Dolomite(Limestone)Aquifer

1.
Sandwiched between the sand/gravel aquifer and a confining
layer of (Maquoketa) Shale.

2.
Covers the eastern most part of the state from Door County
to the Wisconsin and Illinois border.

3.
Because of the fractures found in Dolomite the yield of water
can vary.

4.
Prone to contaminate (again because of the fractures) where
ever the water lies to close to the surface.

Aquifers Of Wisconsin


Sandstone and Dolomite Aquifer

1.
Supplies most of the water for Wisconsin.

2.
Covers the entire state except for the North and Central part of the
state.

*
Excellent aquifer since both rocks are very porous, and or
permeable


Aquifers Of Wisconsin


Crystalline Bedrock Aquifer

1.
Made up of the oldest rock in the state.

2.

Found as the deepest rock in Wisconsin.

3.
Supplies water for North and Central Wisconsin.

4.
Shallow wells provide good supplies of water.

5.
Deeper wells in the aquifer will yield salty water.

Matter


Mixtures


Substances

-
physical combination

of
matter

-
nothing new is made

-
components maintain
their individual
properties

-
have uniform and
definite composition

Suspensions

Colloids

Solutions

Elements

Compounds

Matter

Types

Overall

Features

-
Most basic part of all matter

-
A chemical combination of 2 or more
atoms/elements


-
Represents the building block of all
matter

-
It’s the smallest component is the
浯m散e汥


-
䥴猠獭慬a敳琠c潭灯湥o琠楳 瑨攠aW潭

-
䍡渠扥C扲潫敮e摯睮w楮W漠瑨攠
atoms/elements that make it up by
chemical means


-
Over 100 different elements/atoms are
known to man

Unlike mixtures it has a definite
composition

Only form of matter that cannot be
broken down into something smaller or
more basic

Example from lab

H₂0 after
distillaton

Example from lab: none

All atoms of a given element are
identical with the numbers of
protons(+) and electrons (
-
)

All atoms are electrically neutral

Elements

Compounds

Chemical Bonding

Formation of Ionic Compounds

Formation of Molecular Compounds

(Covalent Bonds)

Polar Covalent

Atomic Structure

Average atomic mas
s

6p
+

+ 6n
°

= 12 (mass

number)

12
amu

(atomic mass units)

Chemical Symbol

Element Name

Atomic Number

= ( number of protons,
also number of electrons)

*
Mass Number

=

(
Protons + Neutrons
)

round atomic mass to whole number

Atomic Structure of Carbon

Electron

Proton

Neutron

Reading and Writing Formulas

Writing Chemical Formulas


Background: Formulas consist of:





Element and Element A B






(
Or)





Element and Polyatomic Ion A BC




Ion:

Multiple elements combined that behave like one element.

When elements want to combine they must lose or gain electrons.



Losing electrons

Cations

Positive Charge

Ex:
Na
+








(+)


Gaining electrons
Anions

Negative Charge









(
-
)

Ex:

Cl
-



Polyatomic Ions
:

2 or more elements behaving as one element
that has a positive or negative charge.

Procedure



1.)
Write down the symbols of the elements in the compound, as seen on
the periodic table




Potassium oxide = K O







2.) Place charges next to each symbol as seen on page 33.






K

뤠†⁏

2



3.)

Crisscross the charges


K

뤠† O

²

K


O

(never write the number 1)



(*
subscript

= tell the number of atoms present : 2 atoms of potassium one
atom of oxygen)


Ex.

Magnesium

Phosphate






Mg

²

† †

₄⁻
³


Metal

Mg
3

(PO

)
2

*Answer to chemical formula for “Magnesium Phosphate”

Cation

Anion

Formula

Name

K⁺


¯

O䍬

P潴慳a極i 䍨汯物摥

Ca SO₄

Ca⁺²

PO₄¯³

NH₄ (NO₃)

Ammonium Nitrate

Al₂ (SO₄)₃

Magnesium
Hydroxide

Calcium Carbonate

Reading Formulas:

*
If only
2 elements
are present:


1.) Read the first element as seen on the periodic table.


2.) Change the ending of the second element to
-
ide
-





Al₂ S₃ = Aluminum Sulfide

Look for the metal!

*If
three or more

elements are present:




1.)
Read the first element listed as seen on the periodic table.




2.)
The second item listed will be a polyatomic ion, and read it
as seen on table on p. 33



Zn Co


㴠婩湣⁃慲扯湡瑥


Reactants

Products

Subscript

Coefficients

Yield

State





Mg
Cl


(
aq
)
+
2

Na
(s)



2

NaCl

(
aq
)
+Mg
(s)


In a water solution

Chemical Equation

Solution Characteristics

1)
All solutions have a solute and solvent.

a.)
Solute:
Materials being dissolved(oxygen sugar

b.)
Solvents:

Material that carries out the dissolving process(water)

2)
Temperature plays a big role in determining the quantity of solute that will
dissolve.

3)
At higher temps more solute will dissolve

4)
Solubility:

The amount of solute that will dissolve in 100 g of water at a
given temperature.

5)
Therefore at a given temperature, water will dissolve only a certain
quantity of solute. (See graph 46)

6)
Saturation:

The condition created when a solvent is dissolving the max
amount of solute possible at a given temperature.

7)
Unsaturated:

A solvent is dissolving less solvent than it can normally
hold at a given temperature

8)
Supersaturated:

A solvent contains more solute that in can normally hold
at a given temperature

Solution Concentration


Terms like saturated, unsaturated, and super saturated are
sometimes inadequate to describe solution concentration.

RIVERS AS SOLUTIONS

1.
Water in rivers dissolves many substances, therefore allowing
for many ions to be released into the water.

2.
Common maters found in river water Limestone bedrock,
upon dissolving will release calcium and magnesium ions into
water.

3.
Salts are naturally found in soil, and they will release different
ions into water.

4.
Road salt from last year is a source of chloride ions

5.
Fertilizer and animal wastes are sources of nitrates and
phosphates

6.
Photosynthesis will produce oxygen

7.
Respiration and decay will produce carbon dioxide and lower
oxygen amounts

8.
Acidic gases dissolve in water and will lower pH


Balancing Equations


*Equations consist of 2 parts:

1.
Reactants:

Materials found left of the arrow.

2.
Products:

Materials found right of the arrow.

3.
To balance an equation, place
coefficients

(numbers) in front of either reactants or products,


in order to balance the number of atoms on both
sides of the equation.