Chapter 11, Chemical Reactions Day 1 is slides 1-30

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Chapter 11, Chemical ReactionsDay 1 is
slides 1-30
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Chemical Equation
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chemical equation is a representation of a
chemical reaction reactants (on left) and
products (on right) are expressed as chemical
formulas. Reactants IN Products OUT
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law of conservation of mass mass is neither
created nor destroyed in a chemical reaction
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law of conservation of mass says whatever is put
into the reaction must come out as products.
i.e., if you put 3 oxygen in, then you must get 3
oxygen out. Same number of each atom on both
sides.
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Conservation of mass Put Same number of each
atom on both sides.(Show brainpop on
conservation of mass.)
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Review 1st slideThis equation violates the Law
of Conservation of Mass.Why? This is
unbalanced. Will balance in later slides.
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Coefficients2Na2S 4Na and 2S This means 2
units of sodium sulfide

• How many atoms in each of the following
• 4MgCl2
• 2Na2CO3
• 3Fe2(SO4)3

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This means 2 units of sodium sulfide2Na2S 4Na
and 2S

• How many atoms in each of the following
• 4MgCl2 4Mg, 8Cl
• 2Na2CO3 4Na, 2C, 6-O
• 3Fe2(SO4)3 6Fe, 9S, 36-O
• Got it? Do in your notes now. 4(NH4)2S

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unbalanced equationthere are not the same
number of each type of atom on both sides of the
equation
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TO BALANCE1.)Only add coefficients (must be
lowest whole numbers) 2.) Never change
subscriptsCO is not the same as CO2!!!!!Now
there are the same number of atoms on both sides
of the equation
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Diatomic Elements There are 7 diatomic
elements, dont forget that these only exist as
diatomic gases.
H2, N2, O2, F2, Cl2, Br2, I2 Cl I F H. Br O N
Says there are 7.
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Try these .



Teacher Note. Do all through slide
17 before reviewing ans on 18

• Na F2 ? NaF

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• H2 O2 ? H2O

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• Al O2 ?

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• Al O2 ? Al2O3

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• Na F2 ? NaF
• H2 O2 ? H2O
• Al O2 ?
• Fe(OH)2 HCl ? FeCl2 H2O

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Answers

• 2Na F2 ? 2NaF
• 2H2 O2 ? 2H2O
• 4Al 3O2 ? 2Al2O3
• Fe(OH)2 2HCl ? FeCl2 2H2O

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Catalyst A substance not used up in a reaction
that speeds up the reaction. Table above is on Pg
348 of text
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What is a catalyst?

• A substance that speeds up a reaction, without
  being changed or used up by the reaction.
• Enzymes are biological or protein catalysts in
  your body.

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Copy and write a balanced equation

• Solid copper reacts with oxygen gas to form solid
  copper I oxide.

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Copy and write a balanced equation

• Solid copper reacts with oxygen gas to form solid
  copper I oxide.
• 4Cu(s) O2(g) ? 2Cu2O(s)

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Balance it. What whole number coefficient will
go in front of CaO?Ca O2 ? CaOA)1 B)
2 C) 3 D)4
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• Quiz 1
• 1. Mg S ? MgS
• 2. Na O2 ? Na2O
• 3. NaOH ? Na2O H2 O2
• LiCl ? Li Cl2
• 5. C18H38 O2 ? CO2 H2O

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• Quiz 1 Answers
• 1. Mg S ? MgS

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• Quiz 1 Answers
• 2. 4Na O2 ? 2Na2O

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• Quiz 1 Answers
• 3. 4NaOH ? 2Na2O 2H2 O2

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• Quiz 1 Answers
• 4. 2LiCl ? 2Li Cl2

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• Quiz 1 Answers
• 5. 2C18H38 55O2 ? 36CO2 38H2O

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• Quiz 1 Answers
• 1. Mg S ? MgS
• 2. 4Na O2 ? 2Na2O
• 4NaOH ? 2Na2O 2H2 O2
• 2LiCl ? 2Li Cl2
• 5. 2C18H38 55O2 ? 36CO2 38H2O

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Day 2. Next SectionPredicting Possible
Products
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The goal of this unit is going to be predicting
possible products in a chemical reaction and then
balancing the final equation.(Charges? How can
they help?)K O2 ? ?
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Charges? How can they help?Review Group1A
1 2A 2 3A 3 5A -3 6A -2 7A -1
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Pg 348
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There are 7 diatomic elements, dont forget that
these only exist as diatomic gases.
H2, N2, O2, F2, Cl2, Br2, I2 Cl I F H. Br O N
Says there are 7 diatomic elements.
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Types of reactions.
Cl I F H. Br O N Says there are 5 types of
reactions.
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Types of Reactions

• There are probably millions of reactions.
• We cant remember them all, but luckily they will
  fall into several categories.
• We will learn a) the 5 major types.
• We will be able to b) predict the products.
• For some, we will be able to c) predict whether
  or not they will happen at all.
• How? We recognize them by their reactants

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Define A,B,C are variables for elements A,B,C
ionic compound, molecular compound, atom, acid,
base, metal, non-metal, or polyatomic ion, etc.
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combination reactionthings combine into 1
thing.Note rxn is reaction.Two or more
substances react to form a single substance.
They combine together.A B ? AB2Na(s)
Cl2(g) ? 2NaCl(s)
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combination reaction (rxn) - two or more
substances react to form a single substance
? 2H2(g) O2(g)? 2H2O(/)
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Try it

• Li S ?

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Try it

• Li S ? Li2S
• Li has a 1 charge
• S has a -2 charge
• Remember the crisscross rule.
• There must be a 21 ratio for the charges to
  cancel.

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Now Balance

• 2Li S ? Li2S

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Mg O2 ?

• Steps
• 1. Find product
• 2. Balance

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Mg O2 ? MgO

• Mg has a 2 charge and O has a -2 charge this is
  the only product that forms. The net charge is
  zero.
• Any time that a metal and a nonmetal react you
  can predict their products based on each of the
  elements common ionic charges.

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Balance it!2Mg O2 ? 2MgO
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K S ?
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 decomposition rxn Compound breaks into
parts.a compound breaks down into two or more
simpler substancesAB ? A B ABC ? A B
C 2H2O ? 2H2 O2
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2 - Decomposition Reactions

• If the compound has more than two elements you
  must be given one of the products
• The other product will be from the missing pieces
• NiCO3 CO2 ___
• H2CO3(aq) CO2 ___

heat
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2 - Decomposition Reactions

• We can predict the products if it is a binary
  compound (which means it is made up of only two
  elements)
• It breaks apart into the elements
• H2O
• HgO

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2 - Decomposition Reactions

• We can predict the products if it is a binary
  compound (which means it is made up of only two
  elements)
• It breaks apart into the elements
• 2H2O 2H2 O2
• 2HgO 2Hg O2

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Try it

• ?
• Na2O ?
• Are either of these diatomic elements?
• Can you predict if the products are gases or will
  be solids based on their position on the periodic
  table?

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What type of reaction is this?H2 F2 ?
2HFA) CombinationB) DecompositionC)
Double-ReplacementD) Combustion
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To solve1. Predict products.2. Write skeleton
eqn.3. Balance the eqn.
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Single-replacement rxn One element replaces
another.one element takes the place of another
element in a compound.
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Remember from beforeH20 is really HOH or HOH-
So only the first H will swap.The second H
will NOT swap.
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Ba Na2SO4 ?

• Will the metals replace each other?
• The more reactive metal will combine with the
  anion. Remember discussing reactivities in the
  periodic table. Lower left is most reactive.
• Activity Table. Is there an easier way? Yes,
  look at page 361, table 11.2. The metal highest
  up in the table will be the one that ends up
  attached to the anion.

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Ba Na2SO4 ?

• Assume the metals will replace each other.
• Do Ba and Na have the same common ionic charge?
• Is Na diatomic?
• What is the charge of sulfate?

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Li H2O ?

• A group 1 metal can replace ONE H from an acid
  and/or water.
• If one H is removed from water than OH- remain
  hydroxide.

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Try it

• Na Cs2O ?
• Assume that the metal will replace the other
  metal in the compound.
• Is the common ionic charge of Na and Cs similar?
• Is Cs a diatomic element?

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Double-replacement rxn two compounds swap an
elementtwo different compounds exchange positive
ions and form two new compounds.
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Try it

• AgNO3 NaCl ?
• Assume the metals will switch places.
• How do you find the charge of Ag?
• Are the charges on the metals similar?

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NaOH HCl ?

• Assume Na and H will switch places.
• Are their charges similar?
• What is HOH?

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H2SO4 Al(OH)3 ?

• Assume that the Al and H switch places.
• Are the charges on Al and H the same?
• The net charge of the products must be equal to
  zero.

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Combustion reaction reacts with oxygen.a
substance reacts with oxygen often producing heat
and lightCXHX O2 ? CO2 H2O
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Combustion reaction reacts with oxygen.Often
we look at Hydrocarbon Combustion. What products
does Hydrocarbon Combustion always produce?CXHX
O2 ? CO2 H2O
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Li O2 ?

• What are the common ionic charges of these ions?
• The net ionic charge of the product must be equal
  to zero.

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C7H16 O2 ?

• What are always the two products of the
  combustions of a CH compound?

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Try it

• Watch the demonstration and try to write a
  balanced equation for what you are seeing.

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What type of rxn is this?NaOH HCl ? NaCl
H2O A) CombinationB) DecompositionC)
Double-ReplacementD) Combustion
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Predict and balance

• HI ?

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Predict and balance

• 2HI ? I2 H2

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Predict and balance

• Na O2 ?

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Predict and balance

• 4Na O2 ? 2Na2O
• combination

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Predict and balance

• Li Al2O3 ?

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Predict and balance

• Li Al2O3 ? Li2O Al
• Single replacement

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Predict and balance

• HNO3 NaOH ?

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Predict and balance

• HNO3 NaOH ? H2O NaNO3

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Combination reactionthings combine into 1
thing. A B ? AB 2 ? 1
Decomposition rxn Compound breaks into parts.
AB ? A B 1 ?
2Single-replacement rxn One element replaces
another.A BC ? B AC 2 ? 2 1
Elem Double-replacement rxn two compounds
swap an element AB CD ? AD CB 2 ? 2
Both Comp Combustion reaction reacts with
oxygen. O2 ?
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Aqueous (aq) dissolved in water Double
replacement reaction involving 2
solutionsPrecipitate a solid that forms in a
liquid and stops the reaction from being
reversible. NaCl(aq) AgNO3(aq) ? NaNO3(aq)
AgCl(s)
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NaCl(s) H2O(l) Na(aq) Cl-(aq) Ionic
compounds dissociate into ions in solution
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Na(aq) Cl-(aq) Ag(aq) NO3-(aq) ?
Na(aq) NO3-(aq) AgCl(s) complete
ionic equation shows free ions in solution
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Ag(aq) Cl-(aq) ? AgCl(s) Net ionic equation
shows only the ions that react to form a solid
(precipitate), the rest of the ions remain in
solution and are called spectator ions
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Try it. Write the net ionic equation.(Predict
products)

• BaCl2(aq) Na2SO4(aq) ?

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Try it. Write the net ionic equation.

• BaCl2(aq) Na2SO4(aq) ? BaSO4(s) NaCl(aq)

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Try it. Write the net ionic equation.

• Ba 2(aq) SO42- (aq) ? BaSO4(s)

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Try it? p. 344

• NaCl(aq) CaCl2(aq) ?

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Pb(NO3)2 (aq) NaCl (aq) ?
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Lab p345, Questions 1-5