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Unit 2: Chemistry - Chemical Processes (24 hours) |
This unit examines the importance of chemical reactions in developing industrial processes and in addressing environmental concerns. Students will conduct chemical reactions using standard scientific procedures.
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Ontario
Curriculum objectives: |
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Text: Science 10, Nelson
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Lesson One |
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Summary: (U1,U8) |
Homework: |
CHEMISTRY
CHEMISTRY: the study of the properties of various substances and how they react with each other
Elements:
substance that cannot be broken down, and still retain
original
properties
Atoms: smallest unit in element
Compounds: two or more elements joined together in one substance
(can
be broken down into elements)
Molecule: two or more atoms together
Periodic
Tables distributed and worksheet: quiz on naming 40 elements will be given next
class
Atomic Structure:
protons = + charge = in nucleus...called the atomic number
(different atoms have different atomic numbers)
neutrons
= 0 charge = in nucleus
electrons
= - charge = around nucleus in shells (2 in first, 8 in others)
BOHR-RUTHERFORD
DIAGRAM REVIEW
Na
= sodium = 11 electrons with 2 electrons first shell, 8 electrons second shell,
1 electron last shell
outermost electrons are called valence electrons, and found in valence (outer)
shell
Chart of valences distributed...
atoms
attempt to fill valence shell with electrons in order to become stable
+ valence
atoms want to lose electrons in order to become stable
(e.g. Na+1 wants to lose one electron, Mg+2 wants to lose
two electrons)
-
valence atoms want to gain electrons
(e.g. Cl-1
wants to gain one electron, O-2 wants to gain two electrons)
-when two
or more atoms share or donate electrons to each other in order to become
stable, chemical
bonds form. The joining of the atoms is called a chemical reaction and produces
molecules.
+
valence atom is written before – valence atom when they are found together in
molecules
Na+1Cl-1
---exchange valence, lose signs----> Na1Cl1 ------>
NaCl (only numbers
greater than 1 must be written)
Sodium has lost one electron while chlorine has gained this electron...now the
atoms are bonded together
Mg+2Cl-1
----> Mg1Cl2------> MgCl2
Magnesium
has lost two electron while two chlorine atoms have gained one electron...now
the atoms are bonded together
Mg+2O-2
----> Mg2O2------>MgO (reduce)
Magnesium
has lost two electron while two oxygen has gained two electrons...now the atoms
are bonded together
BINARY COMPOUNDS
Binary Compounds: are compounds made of 2
different atoms
naming
binary compounds = positive element named, then negative element is named with
"ide" ending
eg.
NaCl = sodium chloride
MgO
= magnesium oxide
MgCl2
= magnesium chloride
H2O
= hydrogen oxide (water)
elements on their own are just called by name (Na=sodium, Au=gold, He=helium)
Some
elements are found in molecular form in nature
(H2 =hydrogen, S8=sulphur, P4
=phosphorous, Cl2 =chlorine, F2 =fluorine, O2
=oxygen)
Hand out
binary compound worksheets
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Lesson Two |
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Summary: (U1,U8) |
Homework: |
RADICALS
RADICALS
or POLYATOMIC IONS: groups of atoms with a specific valence charge
remember...ion
= charged atom which has gained or lost electrons
radicals=groups
of atoms that stay together and carry an overall ionic charge (valence)
eg.
NO3-1 means valence is –1 for this group of atoms
-these
atoms show definite properties when together in the form of a radical
-radicals
bond with atoms or radicals of opposite charge
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Radical |
Formula |
Valence |
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nitrate |
NO3-1 |
–1 |
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chlorate |
ClO3-1 |
–1 |
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carbonate |
CO3-2 |
–2 |
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sulphate |
SO4-2 |
–2 |
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phosphate |
PO4-3 |
–3 |
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hydroxide |
OH-1 |
–1 |
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acetate |
C2H3O2-1 |
–1 |
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permangenate |
MnO4-1 |
–1 |
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ammonium |
NH4+1 |
+1 |
Potassium
with Nitrate:
K+1 and NO3-1 ---> K1(NO3)1
---> KNO3....called potassium nitrate
...to
name molecules with radicals, write the first element and then the radical name
(no "ide" ending)
Na+1 and SO4-2 ---> Na2SO4....called sodium sulphate
-as with
binary compounds, always put the positive valence radical first
Nitrate
with Ammonium ---> NO3-1 with NH4+1
---> NH4NO3 ....called ammonium nitrate
-put
radicals in brackets if there are more than one copy of a radical is present
Calcium and Nitrate ---> Ca+2 and NO3-1
---> Ca(NO3)2 ....called calcium nitrate and has two
nitrates
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Lesson Three |
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Summary: (U1,U8) |
Homework: |
VARIABLE VALENCE ELEMENTS
-some
elements have two potential positive valences, eg. Fe may be +2 or +3
-these
variable valence elements form compounds which must be named using a different
method than previously discussed
Two possible methods exist for naming variable valence compounds...
IUPAC METHOD
–simplest, most accepted, informative method
rules: follow same method as before (add "ide" ending to second
element)
for multivalence elements, show the valence number used in
brackets using a roman numeral
I =1, II =2, III =3, IV =4, V =5, VI =6
eg. Cu+1 Cl-1 = CuCl
is copper (I) chloride, as copper has a valence of +1
Cu+2
Cl-1 = CuCl2 is copper (II) chloride, as copper has a
valence of +2
Fe+3 O-2 = Fe2O3 is
called iron (III) oxide, as iron has a valence of +3
Fe+2
O-2 = Fe2O2 which reduces to FeO, called iron
(II) oxide, as iron has a valence of +2
Fe+3 OH-1 = Fe(OH)3 is called iron (III) hydroxide
PREFIX METHOD
–this method is usually used for non-metals
rules:
add prefix in front of second element, referring to actual number of
second element (not valence number)
CO2 = is called carbon dioxide using the prefix method,
as their are 2 oxygen,
CO2 = is called carbon (IV) oxide using IUPAC method as the valence
of carbon is +4 (C+4O-2 = C2O4
which reduces to CO2)
Prefixes
-mono = 1, eg. CO is carbon
monoxide IUPAC is
carbon (II) oxide (as valence of carbon is +2)
-di
=2, eg.
CS2 is carbon
disulphide
" " carbon (IV) sulphide (as valence of carbon is +4)
-tri
=3, eg.
SO3 is sulphur
trioxide
" " sulphur (VI) oxide (as valence of sulphur is +6)
-tetra =4 eg. CF4
is carbon
tetrafluoride
" " carbon (IV) fluoride
-penta =5 eg. PBr5 is
phosphorous pentabromide " " phosphorous (V) bromide
-IUPAC and Prefixs method should only be used for positive multivalence
atoms.
(e.g. NaCl is sodium chloride because sodium only has one valence Na+1,
not sodium (I) chloride or sodium monochloride)
-do practice sheets on multivalence elements
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Lesson Four |
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Summary: (U1,U8) |
Homework: |
ACID NOMENCLATURE
ACIDS:
Acids
release H+ when mixed with water
All
acids are aqueous (dissolved in water)........(aq)
All
acids start with H
1.
BINARY ACIDS
HCl
= hydrogen chloride is a binary compound not dissolved in water
HCl(aq)
= hydrochloric acid is formed when hydrogen chloride is dissolved in water
For
naming binary acids, use “HYDRO”element”IC acid (“hydo” replaces
"hydrogen", “ide” ending becomes “ic”)
HF
= hydrogen fluoride
HF(aq)
= hydrofluoric acid
2. OXY ACIDS
Acids
that form when H mixes with radicals containing oxygen are called oxy acids
HNO3
= hydrogen nitrate is a binary compound not dissolved in water
HNO3(aq)
= nitric acid is formed when hydrogen nitrate is dissolved in water
For
naming Oxy Acids, use element”IC” acid (“ate” ending of radical becomes “ic”,
hydrogen is removed from name)
H2SO4
= hydrogen sulphate
H2SO4(aq)
= sulphuric acid
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Lesson Five |
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Summary: (D1) |
Homework: |
LAB SAFETY
Review safety rules in lab
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Lesson Six |
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Summary: (D8) |
Homework: |
CLASSIFICATION OF MATTER
Pure
substances –same properties throughout, cannot be broken down physically
Elements –cannot be broken down
chemically eg. O, H, etc.
Compounds –can be chemically broken down
further eg. H2O
Mixtures
–variable properties throughout, can be physically separated
Mechanical mixtures (heterogeneous) –2 or
more visible phases eg. rocks and water are both visible in mixture
Solution (homogeneous) –1 visible phase
eg. salt water, where only water is visible as the salt is dissolved
PROPERTIES
OF MATTER
property
–a quality or characteristic
matter
–anything with mass and volume
Physical
Properties: characteristics of a substance which can be observed and do not
change the chemical composition of the substance
some examples of physical properties: colour, density, clarity, viscosity,
ductility, maleability, odour, taste, hardness, lustre,
melting point, freezing point, conduction of heat, conduction of electricity,
solubility
mass
–amount of matter in an object
weight –measure of pull of gravity
volume
–amount of space an object takes up
State of
Matter (a physical property)
solid:
particles close together, definite shape, definite volume, strong attraction of
particles
liquid:
particles in clumps, further apart, shape of container, definite volume, weak
attraction
gas:
particles on own, far apart, shape of container, indefinite volume, very weak
attraction
physical changes result in same material, with same physical properties, eg. change of state, breaking glass
Changes
of State (a type of physical change)
Liquid
to Gas = evaporation/boiling/vaporization
Gas
to Liquid = condensation
Gas
to Solid = sublimation
Solid
to Gas = sublimation
Solid
to Liquid = melting
Liquid
to Solid = freezing/solidification
Chemical Properties: characteristic chemical reactions a substance may undergo,
resulting in changes in chemical composition
some examples of chemical properties: reactivity or chemical behavior,
reactivity with acids/bases,combustible,
produces oxygen or a poisonous vapour when heated
chemical changes result in new
substance with new chemical composition forming with new physical and chemical
properties
5 indications a chemical change has occurred
1.
new colour
2.
heat produced/lost
3.
precipitate forms
4.
light produced
5.
new gas/odour
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Lesson Seven |
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Summary: (U1,U8) |
Homework: |
CHEMICAL REACTIONS
reactants:
starting material in a chemical reaction
products:
new material that is made by the chemical reaction
an arrow usually indicates the direction of the chemical reaction moving from
reactants to products
REACTANTS
PRODUCTS
A
+ B
----------------> C + D
Word
Equations: Full chemical names of reactants and products are written
e.g. iron is burned in oxygen to produce iron oxide. The word equation for this
reaction is:
iron + oxygen ---------> iron oxide
CaCl2 and Na2SO4 react to form
CaSO4 and NaCl
word
equation for this chemical reaction is:
calcium
chloride + sodium sulphate ---------> calcium sulphate + sodium chloride
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Lesson Eight |
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Summary: (U2,D8) |
Homework: |
BALANCING CHEMICAL EQUATIONS
Law
of Conservation of Mass
-amount
of energy/mass in the universe is constant
“what goes into a chemical reaction must come out, only with the atoms
rearranged"
An
equation should have the same type and number of atoms in the reactants and
products
Equations must be "balanced" in order to reflect this
Helpful
Hints for balancing equations
1.
The formula for a substance cannot be changed (ie. you cannot insert numbers
into the middle of a molecule). All the numbers added are in front of the
molecules.
eg.
H2SO4 may be changed to 2H2SO4 but
you cannot change subscripts in the molecule
2. A
coefficient in front of a molecule affects all atoms in the molecule
eg.
2H2O ----> indicates that there are 4 hydrogen, 2 oxygen
3. A
subscript affects only the elements immediately preceding it in the molecular
formula.
eg.
H2SO4 ----> indicates that there are 2 hydrogen, 1
sulphur, 4 oxygen
4. When
a formula has elements contained within brackets all those elements are
affected by a following subscript
eg.
Ba(OH)2 ----> indicates that there are 1 barium, 2 oxygen, 2
hydrogen as only oxygen and hydrogen are in brackets
5. The
total number of atoms of an element are the product of the coefficient in front
and any subscript.
eg.
3H2SO4 -contains 6 hydrogen, 3 sulphur, 12 oxygen (lack
of a subscript indicates “one” atom is present in a molecule)
e.g. 2Ca(NO3)2 -contains 2 calcium, 4 nitrogen, 12 oxygen
6. When
an atom appears in several molecules or if it appears alone, balance it last.
eg.
Ca(NO3)2 + Na2CO3 ----> CaCO3
+ NaNO3 should be balanced by using all other elements before
balancing the oxygen
-this equation was balanced by starting with Ca. One Ca was on each side of the
equation, so it was already balanced.
-then N was examined, and 2 N were reactants while only 1 N was a product.
-by placing a 2 in front of the product containing N (NaNO3) the
amount of N on both sides of the equation was now the same
Ca(NO3)2 + Na2CO3 ----> CaCO3
+ 2NaNO3
-2 Na were present on both sides now that NaNO3 had been doubled. C
was examined next and there was 1 C on each side.
-oxygen was
examined last, with 9 O ([3x2]+3) in the reactants and 9 O (3 + [2x3]) in
the products.
-the equation has now been balanced
7. When
a fraction would balance the equation, insert the fraction and then multiply
through both sides by the denominator of the fraction to eliminate it.
eg.
KClO3 ----> KCl + O2 would be balance by the addition
of another O, or ½ O2 to the product (remember that molecular
formulas cannot be changed)
KClO3
----> KCl + 3/2 O2 the fraction must now be removed by multipying both sides by the denominator
2
2KClO3
-----> 2KCl + 3O2
8. The
coefficients in the balanced equation must be in their lowest form.
eg.
2H2 + 2Cl2 ---->4HCl must be reduced to the following
lowest form:
H2
+ Cl2 ---->2HCl
eg.
balance the following equations:
N2
+ 3H2 ---->2NH3 (1:3:2)
C4H10 + O2 ----> CO2 + H2O (2:13:8:10)
do balancing questions
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Lesson Nine |
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Summary: (U2,D9) |
Homework: |
LAW OF DEFINITE COMPOSITION
The law
of definite composition states that every compound is composed of elements in a
definite ratio by mass.
This
means that a compound should have in it the same percentage mass of elements making it
up.
Law of Definite Proportions:
In any chemical change, the reacting substances will do so in a definite ratio by mass
eg. 2H2
+ O2 ----> 2H2O
(11.1g) (88.9g) (100g)
-from
these ratios we can compute missing masses
eg. analysis of sucrose showed that a 9.79 g sample contained 4.12 g of carbon, 0.63 g of hydrogen
and 5.04 g of oxygen.
Determine
the percentage of composition of sucrose by mass...
% Mass = mass of element/total mass X 100
Total Mass = 9.79 g
%C
= 4.12 g/9.79 g X 100 = 42.08% Carbon
%H
= 0.63 g/9.79 g X 100 = 6.44 % Hydrogen
%O
= 5.04 g/9.79 g X 100 = 51.48 % Oxygen
eg. When 25.00 g of Ca metal is mixed with 50.00g Cl2
gas, a reaction occurs which makes a solid CaCl2.
All the Ca is used but 5.73 g of Cl2 does not react.
(a) What is the mass of Cl2 that has reacted?
50.00 g Cl2 total – 5.73 g Cl2 unreacted = 44.27 g Cl2
reacted
(b) What is the mass of CaCl2 formed?
Ca(s) + Cl2(g) ----> CaCl2(s)
25.00 g 44.27 g
69.27 g of CaCl2 is formed
(c) What is the percentage composition of CaCl2?
%Ca = Mass Ca/Total Mass X 100 = 25.00 g/ 69.27 g X 100 = 36.09% Ca
%Cl = Mass Cl/Total Mass X 100 = 44.27 g/ 69.27 g X 100 = 63.91%Cl
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Lesson Ten |
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Summary: (D5,D6,D7) |
Homework: |
DECOMPOSITION LAB
Review lab safety rules including the safe use of Bunsen Burners
Do lab examining the Decompostion of Epsom Salts
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Lesson Eleven |
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Summary: (RU3,D13) |
Homework: |
TYPES OF CHEMICAL REACTIONS
There are
four major types of chemical reactions:
1.
Synthesis (combination)
A + B ----> AB
hydrogen + oxygen -----> water
2H2 + O2 ----> 2H2O
2.
Decomposition (breakdown)
AB ----> A + B
water -----> hydrogen + oxygen
2H2O -----> 2H2 + O2
3.
Single Displacement
Z + AB -----> ZB + A (if Z has a positive valence...usually a
metal)
Y + AB -----> AY + B (if Y has a negative valence...usually a
non-metal)
magnesium + silver nitrate ----> silver + magnesium nitrate
Mg + 2AgNO3 ----> 2Ag + Mg(NO3)2(aq)
4.
Double Displacement
AB + XY ----> AY + XB
lead (II) nitrate + potassium iodide ----> lead (II) iodide +
potassium nitrate
Pb(NO3)2(aq) + 2KI(aq) ---->
PbI2(s) + 2KNO3(aq)
GAS TESTS may be used to detect certain gases produced by chemical reactions:
1.
2H2O2 ----> 2H2O + O2(g)
....decomposition reaction
Oxygen gas (O2) results in a glowing splint bursting into
flame
2. Zn(s)
+ 2HCl(aq) ----> ZnCl2 + H2(g) ... single
displacement reaction
Hydrogen gas (H2) results in a flaming splint exploding with a
“pop”
3. CO2 gas turns limewater cloudy
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Lesson Twelve |
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Summary: (U3) |
Homework: |
REACTION TYPE LAB
Do lab studying different reaction types
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Lesson Thirteen |
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Summary: (U4) |
Homework: |
PARTICLE THEORY (KINETIC MOLECULAR THEORY)
Kinetic
Molecular Theory (particle theory) states that:
-all matter consists of small particles
-all
particles of one substance are identical
-spaces
between molecules are large compared to particle size
-particles
attract one another
-particles
are constantly in motion (movement increases with heat)
SOLID--------------->LIQUID------------------------->GAS
particles
most dense------------------------------------------>least dense
lowest energy--------------------------------------->most energy
slowest------------------------------------------------>fastest
RATES OF CHEMICAL REACTIONS
Collision
Model: the rate of chemical
reactions is affected by the number of collisions between the reactants...
increase
reaction rate by: increasing the number of collisions and increasing the
amount of effective collisions
factors
that affect rate=
1.
TEMPERATURE
effect:
high temperature increases the rate of reaction
reason:-particle
motion increases and therefore the number of collisions increases
-energy of particles increases and the
collisions become more effective
2. CONCENTRATION
effect:
higher concentration of reactants increases the rate of reaction
reason:-more molecules packed into a small space increases the number of
collisions
3. SURFACE AREA
effect:
greater surface area of reactants increases the rate of reaction
reason: -surface area increases the area able to be contacted by collisions and therefore increases
the number of collisions
4. CATALYSTS (catalyst=substances
that increase the rate of reaction but are not permanently altered themselves)
effect: catalysts increase the rate of reactions at lower temperatures
reason: -these catalysts lower the energy needed for an effective collision so
more effective collisions occur
OIL SPILL CLEANUP NOTE
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Lesson Fourteen |
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Summary: (U4,D12) |
Homework: |
RATES OF REACTIONS LAB
do rates of reactions lab examining four factors that affect the rates of
various reactions
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Lesson Fifteen |
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Summary:(U7) |
Homework: |
ACIDS AND BASES
Acids
and Bases are water soluble compounds with characteristic properties
-acidic and basic properties are measured with a pH scale (power of hydrogen)
pH
7 is considered neutral (eg. distilled water)
pH
above 7 is considered basic
pH
below 7 is considered acidic
pH 7 = a concentration of 1 X 10-7 mol/L of H+ and is found in
water
-this is the normal concentration of H+ ions produced in
water by the reaction H2O ----> H+ + OH-
pH 10 = 1 X
10-10 mol/L of H+ and is basic indicating less H+ ions are present
than at pH 7
pH
2 = 1 X 10-2 mol/L of H+ and is acidic indicating
more H+
ions
are present than at pH 7
pH 3 = 1 X 10-3 mol/L H+, pH 4 = 1 X 10-4
mol/L H+
pH
2 is 10 times more acidic than pH 3, and 1000 times more acidic than pH 4
-each
number on the pH scale is a change of 10X (towards 0, more acidic/towards 14,
more basic)
-do lab on acids and bases
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PROPERTIES OF ACIDS AND BASES name:________________ Purpose: To determine the properties of acids and bases by
reacting them with different substances.
*NaHCO3 =baking soda
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Lesson Sixteen |
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Summary:(U7,D10) |
Homework: |
pH REVIEW
H2O
--> H+ + OH- …this reaction occurs spontaneously in
water
Water
contains a concentration of 1 X 10-7 mol/L of H+ ions
formed this way
-this is called pH 7 (from the exponent)
-substances
that produce more H+ ions are acids (pH<7)
-substances
that produce less H+ ions are bases (pH>7)
do lab on pH of household items, using universal pH paper
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Lesson Seventeen |
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Summary: (U5,U6) |
Homework: |
ACIDS,BASES AND NEUTRALIZATION
1. ACIDS
-substances
that dissolve in water and release H+ ions (protons)
eg.
HCl ----in water becomes an acid----> HCl(aq) ---which is
actually--> H+(aq) + Cl-(aq)
-acidic properties are caused by the H+ ions
-some properties of acids:
(a)
taste sour
(b)
turn blue litmus paper red
(c)
react with carbonates (eg. baking soda) to produce CO2(g)
(d)
react with metals to produce H2(g)
2. BASES
-substances
that dissolve in water and release OH- ions (hydroxide ions)
eg.
NaOH ----in water becomes a base---->NaOH(aq) ---which is
actually---> Na+(aq) + OH-(aq)
-basic properties are caused by OH- ions