Transcript Chemical Reactionsx

Sugar and Sulfuric Acid yield Carbon and Water
C12H22O11 + H2SO4 → 12 C + 11 H2O
The number of atoms of each
element on the left much be
equal to the number of each on
the right.
• C12H22O11 + H2SO4 → 12 C + 11 H2O
• Is this equation balanced?
C
H
O
S
C
H
O
S
The number of atoms
of each element on the
left much be equal to
the number of each on
the right.
• C12H22O11 + H2SO4 → 12 C + 11 H2O
• Is this equation balanced?
C
H
O
S
C
H
O
S
12
24
15
1
12
22
11
0
• It is not balanced. In actuality, the situation
is a little more complicated than this.
The number of atoms
of each element on
the left much be
equal to the number
of each on the right.
C12H22O11(s) + H2SO4(aq) + 1/2 O2(g) → 11C(s) + CO2(g) + 12H2O(g) + SO2(g)
Is this chemical equation balanced?
C
H
O
S
C
H
O
S
The number of atoms
of each element on
the left much be
equal to the number
of each on the right.
C12H22O11(s) + H2SO4(aq) + 1/2 O2(g) → 11C(s) + CO2(g) + 12H2O(g) + SO2(g)
Yes it is!
C
H
O
S
C
H
O
S
12
24
16
1
12
22
16
1
1. Combination Reaction
2. Decomposition Reaction
3. Single Replacement Reactions
4. Double Replacement Reactions
5. Combustion Reactions
• A combination or synthesis reaction is a chemical
change in which two or more substances react to
form a single new substance.
• General Equation:
• X + Y  XY
• Example
• Magnesium combines with Oxygen to
form magnesium oxide. Formula?
• A combination or synthesis reaction is a chemical
change in which two or more substances react to
form a single new substance.
• General Equation:
• X + Y  XY
• Example
• Magnesium combines with Oxygen to
form magnesium oxide. Formula?
• Mg + O2  MgO
balanced?
•
A combination or synthesis reaction is a chemical
change in which two or more substances react to
form a single new substance.
• General Equation:
• X + Y  XY
• Example
• Magnesium combines with Oxygen to form
magnesium oxide. Formula?
• Mg + O2  MgO
balanced?
• 2Mg + O2  2MgO
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Examples
2K(s) +Cl2(g)  2KCl(s)
S + O2  SO2
Fe(s) + S(s)  FeS(s)
Fe(s) + 3S(s) Fe2S3 (s)
Name these products!
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Examples
2K(s) +Cl2(g)  2KCl(s)
S + O2  SO2
Fe(s) + S(s)  FeS(s)
Fe(s) + 3S(s) Fe2S3 (s)
Name these products!
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Potassium Chloride
Sulfur Dioxide
Iron (II) Sulfide
Iron (III) Sulfide
Copper and Sulfur
• Cu(s) + S(s)  ??? (two reactions possible)
•
Finish this equation.
Copper and Sulfur
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•
•
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Cu(s) + S(s)  CuS(s)
Is this balanced?
Copper is a transition metal
Cu+ and Cu+2
For Copper (II)
• Cu(s) + S(s)  CuS(s) (balanced)
For Copper (I)
• Cu(s) + S(s)  Cu2S(s) (not balanced)
• 2Cu(s) + S(s)  Cu2S(s) (balanced)
Assignment #1
• Complete and balance
this equation for this
combination reaction:
Be + O2 
• Write and balance the
equation for the
formation of magnesium
nitride.
Two Questions:
• Complete and balanced
this equation for a
combination reaction:
• Write and balance the
equation for the
formation of magnesium
nitride from is elements.
Be + O2 
2Be + O2  2BeO
3Mg + N2  Mg3N2
• A decomposition reaction is a chemical change in
which a single compound breaks down into two or
more substances.
• General Equation:
X Y  X +Y
• Mercury (II) Oxide decomposes into Mercury and
Oxygen.
•
A decomposition reaction is a chemical change in
which a single compound breaks down into two or
more substances.
•
General Equation:
•
Mercury (II) Oxide decomposes into Mercury and
Oxygen.
•
•
2HgO(s)  2Hg(l) + O2(g)
X Y  X +Y
• Some of the explosive
properties of dynamite are
attributed to a
decomposition reaction
which produces large
amounts of gas!
• For every 2 moles of TNT
that decomposes, 15 moles
of hot, expanding gases are
produced.
• C7H5N3O6 -- TNT
C7H5N3O6 (s) N2(g) + CO(g) + H2O(g) + C(s).
Balance me!
• Some of the explosive
properties of dynamite are
attributed to a
decomposition reaction
which produces large
amounts of gas!
• For every 2 moles of TNT
that decomposes, 15 moles
of hot, expanding gases are
produced.
• C7H5N3O6 -- TNT
2C7H5N3O6 (s) 3N2(g) + 7CO(g) + 5H2O(g) + 7C(s).
Decomposition Reactions do not have to
break down into elements.
• 2H2O2  2H2O + O2
• H2CO3  H2O + CO2
• What type of Acid is this?
• What are the Products?
ELEPHANT TOOTHPASTE
50ml 30% H2O2 + 10ml Sat. KI + Soap & Food Coloring
Decomposition of Hydrogen Peroxide:
• H2O2(aq) → 2 H2O(l) + O2(g)
• Use KI as a Catalyst!
• H2O2(aq) + I-(aq) → OI-(aq) + H2O(l)
• H2O2(aq) + OI-(aq) → I-(aq) + H2O(l) + O2(g)
• KI-(aq) disassociates and the Iodide ion decomposes a
hydrogen peroxide molecule resulting in the formation
of an OI- ion which decomposes another hydrogen
peroxide molecule producing a new Iodide ion which
can decompose another hydrogen peroxide molecule
and so on…..
• A CATALYST speeds up a chemical reaction!
ASSIGNMENT
• Complete and Balance this
Decomposition Reaction:
HI 
• Through electrolysis, Water Breaks down
into Hydrogen and Oxygen. Balanced
Chemical Equation?
• Write the formula for the binary
compound that decomposes to the
products H2 and Br2
ASSIGNMENT
• Complete and Balance this
Decomposition Reaction:
HI 
• Through electrolysis, Water Breaks down
into Hydrogen and Oxygen. Balanced
Chemical Equation?
• Write the formula for the binary
compound that decomposes to the
products H2 and Br2
2HI  H2 and I2
2H2O  2H2 + O2
2HBr  H2 + Br2
Decomposition: Genie in a bottle
2H2O2 --> O2 + 2H2O
This reaction is usually very slow but can
be increased via a catalyst.
MnO2 + 2H2O2 --> Mn + O2 + 2H2O
• A single replacement reaction is a chemical change in which
one element replaces a second element in a compound.
• General Equation:
• W + X Y  WY + X
• Examples
• Zn(s) + Cu(NO3)2(aq)  Cu(s) +Zn(NO3)2(aq)
• Br2(aq) + NaI(aq)  ?
• Mg(s) + HCl(aq)  ?
• A single replacement reaction is a chemical change in which
one element replaces a second element in a compound. A
halogen can replace a less reactive halogen. A reactive metal
will replace any less reactive metal.
• General Equation:
• W + X Y  WY + X
Notice how a cation
replaces a cation and an
anion replaces an anion.
• Examples
• Zn(s) + Cu(NO3)2(aq)  Cu(s) + Zn(NO3)2(aq)
• Br2(aq) + 2NaI(aq) 2NaBr(aq) +I2(aq)
• Mg(s) + 2HCl(aq)  MgCl2 + H2(g)
• Zn(s) +H2SO4(aq) 
• Cl2(aq)+ NaBr(aq) 
• Fe(s) + Pb(NO3)2(aq) 
• Al(s) + CuCl2(aq) 
• Cl2(aq) + NaI(aq) 
• Ca(s) + H2O(l) 
Assignment:
Assignment
• Zn(s) +H2SO4(aq) 
•
Zn(s) +H2SO4(aq)  ZnSO4(aq) + H2(g)
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Cl2(aq) +NaBr(aq)  NaCl (aq) + Br2(aq)
Cl2(aq) + 2NaBr(aq)  2NaCl(aq) + Br2(aq)
•
Fe(s) + Pb(NO3)2(aq)  Fe(NO3)2(aq) +Pb(s)
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Al(s) + CuCl2(aq)  Cu(s) + AlCl3(aq)
2Al(s) + 3CuCl2(aq)  3Cu(s) + 2AlCl3(aq)
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Cl2(aq) + NaI(aq) l2(aq) + NaCl(aq)
Cl2(aq) + 2NaI(aq) l2(aq) + 2NaCl(aq)
•
Ca(s) + 2H2O(l)  + Ca(OH)2(aq) H2(g)
• Cl2(aq)+ NaBr(aq) 
• Fe(s) + Pb(NO3)2(aq) 
• Al(s) + CuCl2(aq) 
• Cl2(aq) + NaI(aq) 
• Ca(s) + H2O(l) 
•
A double replacement reaction is a chemical change involving an exchange of
positive ions (cations) between two compounds. Often involve the formation of a
precipitate, a gaseous product or water.
•
General Equation:
• A+B- +C+D-  A+D- + B+C•
•
Examples
Na2S(aq) + Cd(NO3)2(aq)  CdS(s) + 2NaNO3(aq) (precipitate forms)
•
2NaCN (aq) + H2SO4(aq)  2HCN(g) +Na2SO4(aq) (poisonous gas)
•
Ca(OH)2(aq) + 2HCl(aq)  CaCl2(aq) + 2H2O)(l) (water forms)
•
A double replacement reaction is a chemical change involving an exchange of
positive ions (cations) between two compounds. Often involve the formation of a
precipitate, a gaseous product or water.
•
General Equation:
• A+B- +C+D-  A+D- + B+C•
•
Examples
Na2S(aq) + Cd(NO3)2(aq)  CdS(s) + 2NaNO3(aq) (precipitate forms)
•
2NaCN (aq) + H2SO4(aq)  2HCN(g) +Na2SO4(aq) (poisonous gas)
•
Ca(OH)2(aq) + 2HCl(aq)  CaCl2(aq) + 2H2O)(l) (water forms)
•
A combustion reaction is a chemical change in which an element or
compound reacts with oxygen often producing energy in the form of heat
and light . Oxygen is always a reactant and usually there is a hydrocarbon as
a reactant.
•
General Equation:
• X + O2  Y
•
Examples
•
Burning of a magnesium strip is a simple combination reaction but it is also classifiable as a
combustion reaction.
•
2Mg(s) + 02(g)  2MgO(s)
•
Similarly
S(s) +O2(g)  SO2(g)
Combustion Of Hydro-Carbons
Combustion of Methane (CH4) which is natural gas or what powers our
Bunsen burners.
CH4 + 202 CO2 + 2H2O
Combustion of Gasoline (2C8H18) which is a mixture of many different and
around 100 different liquids.
2C8H18(l) + 25 O2 (g) →16 CO2(g)+ 18H2O(l)
Combustion of Isopropyl Alcohol (C3H8O) which is not a hydrocarbon but has
the same products as hydrocarbons.
2C3H8O(l) + 9O2(g) ----> 6CO2 (g) + 8H2O(g)
Nitrogen and Sulfur If you were to add in Nitrogen or Sulfur then you would
just include NO2 or SO2 as products as well.
Combustion Of Hydro-Carbons
Combustion of Methane (CH4) which is natural gas or what powers our
Bunsen burners.
CH4 + 202 CO2 + 2H2O
Combustion of Gasoline (2C8H18) which is a mixture of many different and
around 100 different liquids.
2C8H18(l) + 25 O2 (g) →16 CO2(g)+ 18H2O(l)
Combustion of Isopropyl Alcohol (C3H8O) which is not a hydrocarbon but has
the same products as hydrocarbons.
2C3H8O(l) + 9O2(g) ----> 6CO2 (g) + 8H2O(g)
Nitrogen and Sulfur If you were to add in Nitrogen or Sulfur then you would
just include NO2 or SO2 as products as well.
Could you drive a car on the moon?
Assignment: Combustion Problems
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Benzene C6H6
Ethanol CH3CH2OH
Formic Acid HCOOH
Heptane C7H16
Glucose C6H12O6
Sucrose C12H22O11
Read the article on Page 340-341 of
your text book. Answer these questions.
• What three things are needed for fire
to burn?
• Why is it unsafe to use a single kind
of fire extinguisher?
• Why do you want to stop, drop and
roll when on fire?
• What do the letters A,B,C, and D
refer to when dealing with fires.
• Task: Contact your
local fire department
and obtain statistics
on how many class
A,B,C,D fires have
occurred in their area
in the past 6 months
or year.
• As a class we will
create a bar graph of
the results.
• What three things are
needed for fire to burn?
1.
2.
• Why is it unsafe to use a
single kind of fire
extinguisher?
3.
• Why do you want to stop,
drop and roll when on fire?
4.
• What do the letters A,B,C,
and D refer to when dealing
with fires.
Fuel, Oxygen and Energy
A fire extinguisher that controls one type of fire
may enhance other types of combustion
reactions. Spraying water on a magnesium fire
will decompose the water into flammable
hydrogen and oxygen gas. Also, water will
spread a grease fire.
You can smother the fire by removing the air
around it and the ground is cooler so it can
absorb some heat lowering the temperature.
Put noncombustible dirt on your clothes.
A ordinary combustibles, plastic wood, B
involve flammable liquids such as gasoline, C
fires are electrical, D are metal fires.
Model a Fire Extinguisher
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Background: CO2 fire extinguishers
are used to put out grease fires. Why
would you not want to use water
based fire extinguishers?
Purpose: observe the effect of
carbon dioxide on a flame.
Materials: Calcium Carbonate, dilute
hydrochloric acid, 3 beakers, candle,
matches.
Procedure: place a small amount of
calcium carbonate in a beaker. Add
hydrochloric acid and allow several
minutes for the reaction to produce
collectible carbon dioxide gas. Collect
the gas in a second beaker and pour
it into a third beaker with a lit candle
in it.
1.
What happened to the lit candle?
2.
Which is heavier, air or CO2? Don’t
guess, determine the molecular
weight of each.
3.
What is the difference between
being combustible and flammable?
4.
Is paper combustible or
flammable?
5.
Why does the collected CO2 stay in
the beaker until you pour it on the
flame.
11.3
Predicting the Formation
of a Precipitate
You can predict the formation of
a precipitate by using the
general rules for solubility of
ionic compounds.
11.3
Predicting the Formation
of a Precipitate
Will a precipitate form when a
sodium carbonate solution is mixed
with a barium nitrate solution?
11.3
Predicting the Formation
of a Precipitate
Will a precipitate form when a
sodium carbonate solution is mixed
with a barium nitrate solution?
Sodium nitrate is soluble but barium
carbonate is insoluble. The net ionic
equation is
Lab: Combustion of Steel/Magnesium
• Purpose: Does steel get lighter
or heavier during after a
combustion reaction?
• Materials: Superfine steel
wool, plastic sandwich bag,
ring stand, utility clamp,
matches
• Safety: burns readily, goggles,
standard safety procedures.
• Procedure: Determine mass of
steel wool and a container.
Burn the steel wool in a way
that you can preserve the
contents. Determine its mass.
• Prelab Question: What effect
will burning the steel wool
have on it?
• Postlab question: What effect
did burning have on the steel
wool.
• What type of reaction
occurred? Write a balanced
equation for it.
Combustion Part Duex
Combustion of Methane (CH4)
CxHy + (x +y/4)02 xCO2 + (y/2)H2O
CH4 + (1+4/4)02 1CO2 + (4/2)H2O
CH4 + 202 CO2 + 2H2O
Combustion of Gasoline which is a mixture of many different hydrocarbons
but can be approximated as 2C8H18.
CxHy + (x +y/4)02 xCO2 + (y/2)H2O
2C8H18(l) + 25 O2 (g) →16 CO2(g)+ 18H2O(l)
This is the reason your car works.