10 Chemical Equation

8/6/2019 10 Chemical Equation

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Chemical Equation


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Chemical Equation

Chemical equation - summarizes themolecular changes involved in a chemical

reaction.


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R epresentation

A(s) + B(l) + C(g) p Do + Eq + heat

where(s), (l), (g) - signifies the physical states of the compound

o - shows the compound is a gasq - shows the compound is a deposit( - symbolizes presence of heatF - a catalyst

F


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Steps in Writing ChemicalEquation:Step 1 Write the formulas of the reactants.Step 2 Write the formulas of the products by

writing the oxidation numbers of the twocombined elements and applying the criss-cross.


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Steps in Writing ChemicalEquation:Step 3 It is very important to balance the

equation, i.e., the number of atoms ofeach element in the reactant side shouldbe equal to the number of atoms of thesaid element in the product side.


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Types of Chemical R eactions

Combination/ Synthesis/Metathesis DecompositionSingle Displacement Double Decomposition


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Combination/ Synthesis/Metathesis a single substance is formed by union of

two substances

General R ule: A + B p AB


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Special R ules: Combustion

combustion - process of burning; requiresoxygen, O 2


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Special R ules: Combustionmetal + oxygen

metal + oxygen p metallic oxide

barium + oxygen

step 1: Ba + O 2step 2: Ba +2 O -2 p BaOstep 3: 2Ba + O 2p 2BaO


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Special R ules: Combustionnon-metal + oxygen

non-metal + oxygen p non-metallic oxide

sulfur + oxygen

step 1: S + O2step 3: S + O2 p SO2or 2 S + 3O2 p 2 SO3


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Special R ules: CombustionA + O

2

p C + DComplete combustion of hydrocarbonsCH4 + 2O 2 p CO2 + 2H 2O

Incomplete combustion of hydrocarbons2CH 4 + 3O2 p 2CO + 4H 2O


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Special R ules:Metallic Oxide + H

2O p Base

magnesium oxide + water

MgO + H 2O p Mg(OH) 2


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Special R ules:Non-metallic oxide + H 2O p Acid

Sulfur dioxide + water

SO2 + H2O p H2SO3


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Special R ules:Active Metal + Water p Base + H 2

sodium + water

2Na + 2H 2O p 2NaOH + H 2


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Decomposition

A reaction that involves using of heat orelectric current.

It is the opposite reaction of synthesis General R ule: AB p A + B


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Decomposition

Metallic carbonate

CaCO 3 p CaO + CO 2o


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Decomposition

Metal oxide

2HgO p 2Hg + O 2


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Decomposition

Metal nitrate

2NaNO 3 p 2NaNO 2 + O2


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Decomposition

Metal bicarbonate

Mg(HCO 3)2 p MgCO 3 + CO2 + H2O


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Decomposition

Metal oxyhalide

2KBrO 3 p 2KBr + 3O 2


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Single Displacement

the possibility of the positive part of acompound may interact with the negativepart of the second compound.


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Single Displacement

General R ule: AB + C p CB + A

where: A and C are metals and C is moreactive than A.

If not, no reaction will occur.


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Single Displacement

Peter PotassiumSaw Sodium

Carl Calcium Make Magnesium A Aluminum Mangy Manganese Zebra Zinc Carry Chromium Iron Iron Nails Nickel

To T in LiverpoolLead He Hydrogen Caught Copper Ben Bismuth A Antimony Mexican Mercury

Silver Silver Plated Platinum Goat Gold


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Single Displacement

Calcium chloride + sodium

CaCl 2 + 2Na p 2 NaCl + Ca


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Single Displacement

General R ule: AB + C p AC + B

where: B and C are non-metals and C ismore active than B.

Use the Activity Series of the non-metals,(F, O, Cl, Br, I,

S). If not, no reaction will occur.


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Single Displacement

barium chloride + fluoride

BaCl 2 + F2 p BaF 2 + Cl2


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Double Decomposition

General R ule: AB + CD p AD + CB


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Double Decomposition

potassium dichromate + plumbous nitrate


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Double Decomposition: SpecialType Neutralization - a reaction between an

acid and a base that produces a salt andwater.


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Double Decomposition: SpecialTypeHydrochloric acid + sodium hydroxide

HCl + NaOH p NaCl + H 2O


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Addendum

The following elements are alwaysconsidered containing 2 atoms in forminga compound.They are called diatomic molecules.

H 2 , Cl 2 , Br 2 , I2 , F 2 , N 2 , O 2.

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10 Chemical Equation