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Substances are composed of atoms and elements
Substance is matter that has the same fixed
composition, can’t be broken down by physical
processes
Physical processes: boiling, changing pressure, cooling,
or sorting
Chemical process: change the original substance into
new substance(burning, chemical reactions, reaction to
light)
REVIEW :Atom have specific protons for each element
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Two or more elements chemically combined in
specific combinations and composition
H2O, NaCl, H2SO4,
 Water, salt, sulfuric acid
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Mixtures are combinations of substances that are not
bonded together and can be separated by physical
processes (salt water, granite, salt and pepper)
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Heterogeneous Mixtures: mixture where substances
are not mixed evenly
◦ Areas have different compositions
◦ Seeds in watermelon, minerals in granite, cereal in milk
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Homogeneous mixtures: contains 2 or more
substances that are evenly mixed but are not
chemically bonded together
Shampoo, sugar water, Kool-Aid are examples
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Solutions is another name for homogeneous
mixtures
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Solutions form when a solute (salt) dissolves in a
solvent (water)
Forming solids from a solution
◦ Crystallization occurs when cooling or
evaporation takes place and leaves a solid
◦ Precipitates forms from a chemical reaction that
produces a substance that isn’t soluable in solution
and drops out
 Liquid
solid solutions: solid (solute)
dissolves in liquid(solvent) salt in water
 Liquid gas solutions: gas is dissolved in a
liquid (gas dissolved in water: carbonated
water)
 Liquid-liquid solutions: both solute and
solvent are liquids ( vinegar and water)
 Smaller
amount of one gas (solute) is
dissolved in a larger amount of gas
(solvent)
 Both solvent and solute are gases
◦ Example: Our atmosphere contains 78%
Nitrogen and would be the solvent and other
gases in atmosphere would be the solute
 In
solid solutions, the solvent is a solid
 Solute
can be a gas, liquid, or solid
 Solid-solid
solution: alloys are mixture
of 2 or more metals melted together and
mixed (brass, steel)
 Water
the Universal Solvent
◦Aqueous refers to a solution of
where water is the solvent
◦Water can dissolve may different
solutes
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Molecular Compounds:
◦ Water is formed by sharing electrons between 2
atoms of H and 1 atom of Hydrogen
◦ Water molecules when combined have areas of
electrical charges that attract opposite charges, thus
are polar charged
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When compounds are formed by gaining or
losing electrons to bond elements together
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When atoms gain and lose electrons the
number of electrons change and give an
overall charge on the atoms
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Opposite charge atoms attract and hold each
other together
 Because
of the polar charge of water
areas of water molecules attract the
charged particles of ionic compounds
and break them up
 (Page 627 figure 8)
 Water
molecules moves in between sugar
molecules and separate them (thus
dissolving)
 What will dissolve?
 Like dissolves like
◦ Polar solvents dissolve polar solutes (salt and
water)
◦ Nonpolar solvents dissolves non polar
solutes
 If
you have a polar molecule and
nonpolar molecule (unlike polar
molecules) they will not dissolve and will
not form a solution
 Oil
is a nonpolar molecule that will not
mix with polar water, therefore these two
substances will no form a solution
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Solubility is a measurement of how much a solute will
dissolve in a given amount of solvent
It is described as how much solvent can be dissolved in
100 ml of solvent at a certain temperature
At 25@ C grams
dissolved in 100
ml wataer
Potassium
chromate
Barium sulfide
63 g
.00025 g
 Liquid
solid solutions: temperature
affects how much solutes can be
dissolved
 Usually an increase in temperature allows
more solute to be dissolved
◦ Notice on chart that NaCl and CaCO3
become less soluble in higher temperatures
Liquid-gas solutions: increase in temperature
decrease the solubility of a gas dissolved in it
 Carbon dioxide is dissolved under pressure in
water in pop cans
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◦ Opening a warm can of pop vrs a cold can,
the gas is released much faster and leaves the
solution under warmer conditions faster
 A saturated
solutions can hold no more
solute in solution at a given temperature
or pressure
 It will fall to bottom of solvent
 A hot solution can hold more solute than
at lower temperatures and when cooling
the hot saturated solution a
supersaturated solution may form
 Rate
of dissolving is sped up by:
◦ Increasing temperature
◦ Crushing the solute
◦ Stirring the solution
 Concentration
of a solution tells you
how much solute is present compared to
the amount of solvent
◦ It is recorded by using percent of solute is
compared to solvent
◦ Juices concentration are written by 15%,
20% etc
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When a solute is added to water (salt water)
and you want to freeze it , a lower
temperature is needed (to freeze salt water
could be 31℃)
If you want to boil salt water a greater
temperature is needed to boil it
 Acids:
are substances that release
positive H+ ions in water called a
hydronium ion
 When
an acid mixes with water, acid
dissolves and releases H+ ion
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Sour taste
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Conduct electricity
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Corrosive (break down substances)
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React strongly with metals releasing H gas
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Vinegar (acetic acid), citric acid, ascorbic acid we are
familiar with
H2SO4 (sulfuric acid)
◦ Production of fertilizers, batteries, paint
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HCl (hydrochloric acid)
◦ Muratic acid used in pickling that removes impurities from
the surfaces of metals, cleans motar, bricks
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HNO3 (nitric acid) use in fertilizer, dyes, and plastic
 Bases
are substances that accept H+ ions
and give off to a solution of water with
OH- ions
 Feels
soapy, slippery
 Taste bitter
 Corrosives
 Conduct electricity
 Cleaning
products
 Your blood is basic in solution
 NaOH (sodium Hydroxide) is known as
lye and is used to make soap, clean
ovens, unclog drains
 CaOH (calcium hydroxide) often called
lime is put on athletic fields to mark lines
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pH is the measure of how acidic or basic a solution is
Ranges from 0-14 where neutral pH is at 7
Below 7 covers the range of acid solutions (closer to 0
is more acidic0
Above 7 covers range of basic solutions (closer to 14 is
more basic)
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Some acids are helpful (HCl in stomach to digest food
however too concentrated HCl will eat away on tissue
If more H+ (hydronium ions) are present the higher the
acidic content (lower pH)
Bases with large amounts of OH- ions (hydroxide) have
greater concentrations and are more basic (higher pH)
Each number on pH is 10 fold greater or smaller than
the number before it:
Comparing ph3 to ph1 is a difference of 2
2
102 means that there is a difference of
100 times more acidic
 Indicators
are compounds that react with
acidic and basic solutions and produce
certain colors to indicate their acidity or
basicity tendencies
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Neutralization is the reaction of an acid with a
base
When an acid and a base are combined, they
will neutralization each other and the
resulting pH will be 7
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NaOH + HCl
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Base
acid
NaCl + H2O
salt
water