Types of Chem Reactions

8/13/2019 Types of Chem Reactions

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Basic Types of Chemical Reactions

1. Combination or Synthesis - a reaction where in two

elements combine forming one product.Eq: A + B AB

a. Metal + Nonmetal binary compound

Mg + Cl2 Mg Cl2

2Na + S Na 2S

4Fe + 3O2 2 Fe 2O3

b. Metal + O2 Metal oxide or basic anhydride

4Na + O2 2 Na 2O


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c.Nonmetal + O2 Nonmetal oxideor acid anhydride

S + O2 SO2

4P + 3O2 2P2O3

C + O2 CO2


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d. Metal oxide + H 2O Base

or basic anhydride

Na 2O + H 2O NaOH

e. Nonmetal oxide + H 2O Acid

or acid anhydrideSO2 + H 2O H 2SO3


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2.Decomposition or Analysis

- reaction wherein a compound (reactant) breaks into two or more

products ( usually with the use of heat, )

Eq: AB A + B

Chlorates: KClO3 KCl + O2


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Carbonates:CaCO3 CaO + CO2

*Except carbonates of IA Family( ex: lithium carbonate,sodium carbonate, potassium carbonate ). They are not

decomposed further into oxide and carbon dioxide.

HCO3- :Ca(HCO3) 2 CaO + CO2 + H2O

Hydrates:

CuSO4 .5 H2O CuSO4 + 5 H2O


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ELECTROLYSIS

H2O O2 + H2

Metal Oxide :

HgO Hg + O2

Sugars:

C6H12O 6 6 C + 6 H 2O


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3. Substitution or Single Displacement

a. Hydrogen Displacement2 Na (s) + 2H2O(cold) 2NaOH(aq) + H2(g)

Very reactive

Al (s) + H2O(steam) Al 2O3 + H2

Moderately active

Zn + 2HCl ZnCl2 + H2(g)


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The Activity Series for Metals


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b. Metal Displacement

CuSO4 + Fe Fe2(SO4)3+ Cu

(more active)

c. Halogen DisplacementCl2+ KI KCl + I2

(more active)


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4. Exchange, metathesis, Double Decomposition

6 Na 2SO4 + 2Ca3(PO4) 2 4Na 3PO4 + 6CaSO4

5. Precipitation

Pb(NO3) 2+ Na 2CrO4 2Na NO3 + PbCrO4(s)


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6. Neutralization Reaction

Acid + Base Salt

HCl + NaOH NaCl

SO2 + CaO CaSO3


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Chemical formularepresents the composition of onemolecule or ionic compound in terms of chemical symbols.

a. Molecular formulashows the actual number of atoms of elements in a

molecule.ex: C6H 12O6 ( sucrose), C6H6 (benzene ) ,C2H2(acetylene) .

b.Empirical formulagives the simplest whole number ratio of atoms ofelements in a molecule ex: C H2O ( sucrose), C H (benzene ) , C H(acetylene)

c.Lewis formula shows the valence electrons of atoms of elements in amolecule.

.. .. ..

ex: H: O : O: H (hydrogen peroxide) H: O :H (water)

.. .. ..d. Structural formulashows the binding of atoms of elements in amolecule.

ex: H-OO -H (hydrogen peroxide) H- O -H (water)


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c.Lewis formula shows the valence electrons ofatoms of elements in a molecule.

.. ..ex: H: O : O: H (hydrogen peroxide) H: O :H

.. .. ..(water)

..

d. Structural formulashows the binding of atomsof elements in a molecule.

ex: H-OO -H (hydrogen peroxide) H- O -H( water ..


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Chemical Properties

qualities that can be observed after

alteration of composition of the substance

Ex: iron rust, hydrogen is flammable


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Extrinsic or Extensive Properties

are properties that depend on the amount of the

substance in a sample

Ex: volume, length, mass

Intrinsic or Intensive Propertiesdo not depend on the amount of substance ex.

density, boiling pt. melting pt


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Changes of Matter

Physical Changechange in size, shape, physical state,

no change in nature or compositon.

Ex: freezing of water,

pulverizing salt

distillation of wine


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Chemical Change change in the compositon of the

substance

a new substance is formed. ex iron nail (Fe) rust (Fe2O3)

charcoal (C) CO2

Fermentation of fruit juice


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Atomic Structure :

Atom- basic unit of an element that can enter into achemical reaction, retains the identity of element

Electron(discovered by Joseph John Thomson) isnegatively charge(-) particle

Neutron(discovered by James Chadwick) iselectrically neutral particle.

Protonand atomic nucleus (by Ernest Rutherford)positively charged(+) particle.

Atomic number (Z) = the number of protons in the nucleus

of an atom.Mass number (A) = the total number of protons + number of

neutrons

= atomic number + number of neutrons


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Atomic number(Z) = the number of protons in the

nucleus of an atom.

Mass number(A) = the total number of protons +

number of neutrons

A

X

Z

12

6 C


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Electronic Structure of Atoms

Aufbau PrincipleAtomic orbitals

Electronic configuration

Octet Rule

Hunds Rule


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Chemical formularepresents the composition of one molecule orionic compound in terms of chemical symbols.

a. Molecular formulashows the actual number of atoms of elements in a

molecule.ex: C6H 12O6 ( sucrose), C6H6 (benzene ) ,C2H2(acetylene) .

b.Empirical formulagives the simplest whole number ratio of atoms ofelements in a molecule ex: C H2O ( sucrose), C H (benzene ) , C H(acetylene)

c.Lewis formula shows the valence electrons of atoms of elements in amolecule.

.. .. ..

ex: H: O : O: H (hydrogen peroxide) H: O :H (water)

.. .. ..d. Structural formulashows the binding of atoms of elements in a molecule.

ex: H-OO -H (hydrogen peroxide) H- O -H (water)


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Reduction Oxidation Reaction

Molecular Equation (Valence Change Method)NaNO2+ K2Cr2O7+ H2SO4= NaNO3+K2SO4+ Cr2 (SO4)3+ H2O

Ionic Equation (Valence Change Method)

NO2 + Cr2O7 + H + = NO3 -1 + Cr + H2O

Half Reaction or Ion-electron method

NO2-1 = NO3

-1

Cr2O7-2 = Cr+3

+3

-2

-1


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Redox

Balance the eq. using Valence change or Ionelectron method . Answer #1-10

MnO4-1

+ ClO2-1 +H2O = MnO2

+ ClO4-1+ OH-

___1. Oxidation no. of Mn in MnO4-1___2. Oxidation no. of Cl in ClO 4

-1

___3. electron lost/mole ___9. coefficient of ClO2-1

___4. electron gained/mole ___10. coefficient of MnO2

___5 Identify the OA

___6. Which is the RA?

___7. Which is the reduction product?

___8. Which is the oxidation product?


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Accuracyhow close a measurement is to the truevalue

Precisionhow close a set of measurements are to each

other

Accurate&Precise

Precise but

not accuratenot precise &

notaccurate


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Concentration Units

Molaritymoles of solute per liter of solutionM= moles solute moles = g solute

liter of solution molar mass

g solute

M = molar mass

liter solution


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Normalityno of equivalents of solute perliter of solution

N = equivalents of solute

liter of solution

g solute

N = eq wt

liter of solution


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% by mass = mass solute X 100mass of solution

Mole fraction solute (X2) = mole solute

mole solution

Mole fraction solvent (X1) = mole solvent

mole solution


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Concentration Units

1.Calculate the % by mass of the solute in:a. 5.50 g NaBr in 78.2 g solution

b. 31.0 g KCl in 152.0 g water

2.A solution is prepared by mixing 62.5 mlC6H6(MW 78g/mol) with 80.3 ml toluene(MW

92.0g/mol)

density C6H60.867 g/mldensity C7H8 0.87 g/ml.

Types of Chem Reactions

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