1 Section 11.2 p. 330 Types of Chemical Reactions.

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Section 11.2Section 11.2p. 330p. 330

Types of Chemical Types of Chemical ReactionsReactions

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Types of Reactions6 major types. predict the products predict whether or not they will happen at allHow? We recognize them by their reactants

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#1 - Combination Reactions Combine = put together 2 substances combine to make one

cmpd (also called “synthesis”) Ca + O2 CaO

SO3 + H2O H2SO4

predict products, especially if reactants are 2 elements

Mg + N2 Mg3N2 (symbols, charges, cross)

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Complete and balance: Ca + Cl2 Fe + O2 (assume iron (II) oxide is the product)

Al + O2 Remember first step…write correct

formulas – you can still change subscripts at this point, but not while balancing!

Then balance by changing just coefficients only

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#1 – Combination ReactionsAdditional Notes:

a) Some nonmetal oxides react with H2O - produces acid:

SO2 + H2O H2SO3

b) Some metallic oxides react with H2O - produces base:

CaO + H2O Ca(OH)2(how “acid rain” forms)

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#2 - Decomposition Reactionsdecompose = fall apartone reactant breaks apart into 2 or

more elements or cmpdsNaCl Na + Cl2

CaCO3 CaO + CO2

Note: energy (heat, sunlight, electricity, etc.) usually required

electricity

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#2 - Decomposition Reactionspredict products if binary cmpd

(made of 2 elements)

–It breaks apart into the elements:H2OHgO

electricity

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#3 - Single Replacement ReactionsOne element replaces another (new

dance partner)

Reactants must be an element & cmpd

Products will be a different element and different cmpd

Na + KCl K + NaCl F2 + LiCl LiF + Cl2

(Cations switched)

(Anions switched)

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#3 Single Replacement Reactions Metals replace other metals (they can

also replace H) K + AlN Zn + HCl Think of water as: HOH

–Metals replace first H, then combines w/ hydroxide (OH).

Na + HOH

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#3 Will a single replacement reaction occur?

can even tell whether or not single replacement rxn will happen:–b/c some chemicals more “active” than

others–More active replaces less active

Look at Activity Series of Metals–Higher on list replaces lower

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The “Activity Series” of Metals Lithium Potassium Calcium Sodium Magnesium Aluminum Zinc Chromium Iron Nickel Lead HydrogenHydrogen Bismuth Copper Mercury Silver Platinum Gold

1) Metals can replace other metals, if they are above metal trying to replace (i.e. Zn will replace Pb)

2) Metals above H can replace H in acids.

3) Metals from Na upward can replace hydrogen in H2O

Higher activity

Lower activity

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The “Activity Series” of Halogens

Fluorine Chlorine Bromine Iodine

Halogens can replace other halogens in compounds, if they are above halogen they are replacing

2NaCl(s) + F2(g) 2NaF(s) + Cl2(g)

MgCl2(s) + Br2(g) ???No Reaction!

???

Higher ActivityHigher Activity

Lower ActivityLower Activity

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#3 Single Replacement Reactions Practice:

Fe + CuSO4

Pb + KCl

Al + HCl

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#4 - Double Replacement Reactions Two things replace each other.

–Reactants must be two ionic compounds, in aqueous solution

NaOH + FeCl3 –positive ions change place (dance partners)

NaOH + FeCl3 Fe+3 OH- + Na+1 Cl-1

= NaOH + FeCl3 Fe(OH)3 + NaCl

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#4 - Double Replacement Reactions Have certain “driving forces”, or reasons

–only happens if one product:

a) doesn’t dissolve in water & forms a “precipitate”, or

b) is gas that bubbles out, or

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Complete and balance:assume all of the following

reactions actually take place:

CaCl2 + NaOH

CuCl2 + K2S

KOH + Fe(NO3)3

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How to recognize which type?Look at the reactants:

E + E =Combination

C = Decomposition

E + C = Single replacement

C + C = Double replacement

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#5 – Combustion Reactions Combustion means “add oxygen” Normally, a cmpd composed of only

C, H, (and maybe O) is reacted with oxygen – called “burning”

Complete combustion, products are CO2 and H2O

If incomplete, products are CO or C and H2O

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Combustion Reaction Examples:

C4H10 + O2

C6H12O6 + O2

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#6 – Acid Base Acid with a base produces a salt and

water The cation in the salt comes from the

base; the anion come from the acid

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Examples of Acid/Base HCl (aq) + Ca(OH)2 (aq) CaCl2 (aq) + H2O (l)

Acid Base Salt Water

H2SO4 (aq) + Fe(OH)3 Fe2(SO4)3 (aq) H2O

Acid Base Salt Water

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Practice Examples: H2 + O2

H2O Zn + H2SO4 HgO KBr + Cl2

AgNO3 + NaCl

Mg(OH)2 + H2SO3

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SUMMARY: An equation... Describes a rxn Must be balanced (follows the Law of

Conservation of Mass) only balance by changing coefficients special symbols to indicate physical

state, catalyst or energy required, etc.

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Reactions 5 major types We can tell what type they are by

looking at reactants Single Replacement happens based on

the Activity Series Double Replacement happens if one

product is: 1) a precipitate (an insoluble solid), 2) water (a molecular compound), or 3) a gas