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OXYGEN
General Properties

  • Oxygen is a colorless, tasteless, odorless gas, and exist in a diatomic structure.
  • Oxygen is the first member of group 6A with electron configuration 1s2 2s2 2p4
  • It is valance 2, oxidation number -2 with halogens oxd. no 2
  • It is a non-metal.
  • There are three stable isotopes of oxygen 16O  17O  18O
  • It has two allotropes: 02 and 03
  • Oxygen is the most abundant element on the earth. Air, water and many organic compounds.

Preparation of Oxygen in the Laboratory
1. Heating of metal oxides:
2HgO ------ 2Hg + O2
         Ag2O ------- 2Ag + O2
2. Heating of peroxides :
         Na2O2-------- 2Na2O + O2
         H2O2 --------- H2O + O2
3. Heating of some nitrate and chlorate compounds:
         2NaNO3 ------- 2NaNO2 + O2
         2KClO3 -------- 2KCl + 3O2
4. Heating of permanganate compounds:
         2KMnO4-----------K2MnO4 + MnO2 + O2
5. Electrolysis of water:
         2H2O-------------O2 + H2     
        
     Reactions of Oxygen
1. Oxygen reacts with alkali metals to form oxides, peroxides and superoxides:
         4Li + O2 ------ 2Li2O
         2Na + O2 ------Na2O2
         Cs + O2 ------- CsO2
2. All nonmetals react with oxygen gas. Depending on the kind of nonmetal and amount of oxygen different types of oxides may be formed:
         2C + O2 -------- 2CO
         C + O2--------CO2
         S + O2 -------- SO2
         2S + O2 --------2SO3
         N2 + O2 -------- 2 NO (3000 C)
3. Oxygen gives combustion reactions with organic compounds.
         CH4 + 2O2 ------ CO2 + 2H2O

SULFUR
General Properties

  1. Sulfur is the second member of group 6A in the periodic table.
  2. It’s electron configuration ends with 3s2 3p4
  3. Sulfur is a nonmetal and poor conductor of heat and electricity.
  4. It is insoluble in water but soluble in CS2
  5. There are three common allotropes of sulfur: rhombic, monoclinic and plastic sulfur.
  6. In nature, sulfur exist both in free form and in compounds. (S8)
  7. Sulfur is a yellowish solid.
  8. Oxidation number of S can be : -2, -1, 0, +2, +4, +6

     Reactions of Sulfur

  1. It reacts with active metals

2Na + S ® Na2S
     It reacts with other metals when heated except Au
Zn + S ® ZnS
2Al + 3S ® Al2S3

  1. It also reacts with nonmetals

H2 + S ® H2S
C+ 2S ® CS2
2P + 5S ® P2S5
S + O2 ® SO2
S + 2F2 ® SF4
S + 3F2 (excess) ® SF6

  1. Sulfur can also effect some compounds

S+ Na2S ® Na2S2
S + 2H2SO4 (conc.) ® SO2 + 2H2O
S + 6HNO3  (conc.) ®  H2SO4 + 6NO2 + 2H2O
3S + 6 NaOH ® Na2SO3 + 2Na2S + 3H2O

     Oxides of Sulfur
1. Sulfur dioxide SO2
 It is formed by the combustion reaction of S or FeS2
S + O2 ® SO2
4FeS2 + 11O2 ® 2Fe2O3 + 8SO2

It is a toxic, colorless gas with a sharp, bad odor.

Sulfur dioxide is an acidic oxide so it reacts with basic substances:
SO2 + CaO ® CaSO3
SO2 + 2NaOH ® Na2SO3 + H2O

By dissolving in water, it gives sulfurous acid, H2SO3
SO2 + H2O « H2SO3
H2SO3 is an unstable acid. It observes O2 from air and turns to H2SO4.

SO2 plays a major role in producing acid rain.

2. Sulfuric acid H2SO4
Sulfuric acid is a colorless, nonvolatile (flying) and hydroscopic   (likes water) liquid.

It is one of the most important products of the chemical industry. Sulfuric acid is used in paints and pigments, plastics, cleaning metals, soaps and detergents, tanning leather, fibers and dyes, fertilizers.

It is a strong acid.

It reacts with metals and produces H2 gas.
Zn + H2SO4 ® ZnSO4 + H2
Fe + H2SO4 ® FeSO4 + H2

It may reacts with inert metals too.
Cu + 2H2SO4 ® CuSO4 + SO2 + 2H2O

It reacts with bases, basic oxides and amphoteric oxides to produce salt and water.
MgO + H2SO4 ® MgSO4 + H2O
Al2O3 + 3H2SO4 ® Al2(SO4)3 + 3H2O
2NaOH + H2SO4 ® Na2SO4 + 2H2O
2NaOH + H2SO4 ® Na2SO4 + 2H2O (excess acid)

It is a diprotic acid. It ionizes in two steps.
H2SO4 «H + HSO4
HSO4 « H + SO4

NITROGEN FAMILY

  • The members of group 5A are nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb) and bismuth (Bi).
  • Group 5A starts with nitrogen. That is why the group is called nitrogen family.
  • Nitrogen and phosphorus are nonmetals, arsenic and antimony are metalloids, and bismuth is a metal. Metallic property increases from top to bottom in a group.
  • Nitrogen is the only gas in the group, the others are solid.
  • The electron configuration of the elements in this group end with ns2np3.So each element has 5 valance electrons. Thus the elements show oxidation states-3, +3, +5, but nitrogen shows oxidation states -3, +1, +2, +3, +4, +5.
  • All have allotropes, except nitrogen and bismuth. Phosphorus has white, red and black allotropes, and arsenic has black, yellow and grey allotropes.

NITROGEN
GENERAL PROPERTIES

  •  7N: 1s22s22p3
  • Nitrogen is a colorless, odorless and tasteless gas.
  • It exist as diatomic molecules in the atmosphere.
  • The percentage of N in the air is 78%.
  • Nitrogen is a very important element for living organisms. It is part of the structure of proteins and nucleic acids.
  • Nitrogen has two isotopes: 14N and 15N
  • It is mildly (slightly) soluble in water and lighter than air.
  • The bonds between nitrogen atoms are very strong. Therefore, nitrogen gas does not react with acids, bases, water or halogens at STP. At ordinary temperatures nitrogen is very inert so it needs energy to give reactions. This is explained with is structure.

 

  • Nitrogen is used in production of ammonia (NH3) and nitric acid (HNO3). Liquid nitrogen is used as a refrigerant to freeze foods. It is used as a blanketing gas whose purpose is protect a material from oxygen during processing or storage. Thus, electronic components are often made under a nitrogen atmosphere.

 

PREPARATION IN THE LABORATORY
1. Heating the mixture of NaNO2 and saturated NH4Cl
NaNO2 + NH4Cl ® NaCl + 2H2O + N2
2. Reduction of copper II oxide with ammonia
2NH3 + 3CuO ® 3Cu + N2 + 3H2O

3. Other chemical methods for preparation of nitrogen
2NaOH + CO2 ® Na2CO3 + H2O then
2Cu + air ® 2CuO + 2N2
2NaN3 heat ® 2Na + 3N2
(NH4)2Cr2O7 heat® N2 + Cr2O3 + 4H2O

 

     REACTIONS
1. At normal temperature it reacts with only lithium metal.
6Li + N2 ® 2Li3N
2. At high temperature it reacts with other metals to produce metal nitrides.
3Mg + N2 ® Mg3N2
3. It reacts with oxygen at very high temperature.
N2 + O2 ® 2NO (3000 C)
4. At high temperature and at high pressure it reacts with hydrogen.
N2 + 3H2 ® 2NH3 (400-500C 100-200atm)
5. It reacts with halogens.
N2 + 3I2 ® 2NI3
N2 + 3F2 ® 2NF3

 

COMPOUNDS of NITROGEN
1. Ammonia (NH3)
General Properties of Ammonia

  • The molecular structure of ammonia is a pyramidal shape. Nitrogen has three polar covalent bonds with three hydrogen atoms. Nitrogen has also one unshared electron pair.
  • Polar compounds dissolves in polar compounds. Ammonia is very soluble in water. (like dissolves like)
  • It is a colorless gas with a sharp smell.
  • Ammonia sharply irritates the eyes and air passages to the lungs.
  • At high pressure ammonia is liquefied easily. Liquid ammonia has large heat of evaporation. Therefore it is used in refrigerating devices.

Uses of Ammonia

  • In the production of nitric acid and fertilizers.
  • In textile technology.
  • It is used for explosives.
  • It is used to produce hydrazine (N2H4) which is used as fuel for rockets.

Preparation of Ammonia
In the laboratory ammonia is prepared by heating ammonium chloride, NH4Cl with a strong base, such as NaOH or Ca(OH)2.
NH4Cl + NaOH ® NaCl + NH4OH (NH3 + H2O) [the NH4OH formed is unstable at reaction conditions and readily decomposes to NH3 and H2O.]
In the industry, ammonia is obtained directly by the Haber-Bosch Process:
N2 + 3H2 ® 2NH3 (heat,pressure Al2O3)
    
Reactions of Ammonia
1. Rxn with water
NH3 + H2O ® NH4+ + OH-  (NH4OH)
2. Rxn with acids
NH3 + HCl ® NH4Cl
3. Rxn with oxygen
4NH3 + O2 ® 2N2 + 6H2O
4NH3 + 5O2 ® 4NO + 6H2O (presence a catalyst Pt-heat)
4. Rxn with metal oxides (good reducing agent)
NH3 + 3CuO ® 2Cu + N2 + 3H2O
    
     Ammonium Salts
NH4Cl: ammonium chloride
NH4ClO3: ammonium chlorate
(NH4)2S: ammonium sulfide
(NH4)2SO4: ammonium sulfate
(NH4)3PO4: ammonium phosphate
NH4NO3: ammonium nitrate
    

Reactions of Ammonium Salts
1. Dissociation:
NH4Cl ® NH4+ + Cl-
(NH4)3PO4 ® 3NH4+ + PO43-
2. Rxn with other salts:
NH4Cl + AgNO3 ® NH4NO3 + AgCl
(NH4)2SO4 + BaCl2 ® 2NH4Cl + BaSO4
3. Rxn with acids:
NH4Cl + H2SO4 ® (NH4)2SO4 + 2HCl
NH4NO3 + H3PO4 ®    (NH4)3PO4 + 3HNO3
4. Rxn with alkalis:
NH4Cl + KOH ® KCl + NH4OH (NH3 + H2O)
(NH4)2SO4 + 2NaOH ® Na2SO4 + NH4OH (NH3 + H2O)
5. Decomposition rxns:
NH4Cl ® NH3 + HCl heat
NH4NO3  ® N2O + H2O heat
(NH4)2SO4 ® 2 NH3 + H2SO4 heat

Example: N2 ®NH3®(NH4)3PO4® NH3®NO
N2 + 3H2 ® 2NH3
NH3 + H3PO4 ® (NH4)3PO4
(NH4)3PO4 ® NH3 + H3PO4 heat
4NH3 + 5O2 ® 4NO + 6H2O

2.Nitric acid(HNO3)
Nitric acid is the third most important industrial acid ( after sulfuric acid phosphoric acid).
Nitric acid is a colorless,fuming liquid.
It is used to prepare fertilizers, explosives, nylon, and polyurethane plastics.
         Preparation
-In industry(Ostwald process)
4NH3 + 5O2 ® 4NO + 6H2O (Pt catalyst)
2NO + O2 ® 2 NO2
3NO2 +   H2O ® 2 HNO3 + NO
-In the laboratory
NaNO3 + H2SO4 ® NaHSO4 + HNO3
                Reactions of Nitric Acid
1. Dissociation rxn:
HNO3  ® H+ + NO3-
2. Rxn with bases:
HNO3 + KOH ® KNO3 + H2O
HNO3  + Mg(OH)2 ® Mg(NO3)2 + H2O
3. Rxn with basic oxides:
2HNO3 + CuO ® Cu(NO3)2 + H2O
4. Rxn with salts with weak acids:
2 HNO3 + Na2CO3 ® 2NaNO3 + CO2 + H2O
5. Rxn with metals (conc. nitric acid):
HNO3 + Cu ® Cu(NO3)2 + H2O + N2O
HNO3 + Fe ® no rxn
HNO3 + Mg ® Mg(NO3)2 + H2O + NH3
If dilute nitric acid used, hydrogen gas will form!!

3.Oxides of Nitrogen
Nitrogen can form six different oxides: N2O,NO,NO2,N203,N204 and N2O5.
a) Di nitrogen monoxide (N2O N=N=O):
Sometimes it is called nitrous oxide, or laughing gas.
It is colorless and nontoxic gas.
It is used in medicine as anesthetic substance.
It is thermodynamically unstable. It decomposes quickly at high temperature.
2N2O ® 2 N2   + O2 (heat)
In the laboratory it is prepared by carefully heating of ammonium nitrate:
NH4NO3 ® N2O + H2O (heat)
b) Nitrogen monoxide (NO N=O):
It is commonly called as nitric oxide. It is colorless, toxic and odorless gas.
N2   + O2 ®  2NO
In the laboratory NO is prepared by the oxidation of cupper with dilute nitric acid:
3Cu + 8 HNO3 ® 3Cu(NO3)2 + 2NO + 4H2O
         c) Nitrogen dioxide (NO2 O=N-O)
It has a characteristic odor which is usually seen as a reddish-brown color.
In the laboratory NO2 gas is prepared by the reaction below:
Cu + 4 HNO3 ® Cu(NO3)2  + 2NO2 + 2H2O

Exercises on Nitrogen

  • What is the oxidation number of nitrogen in the following compounds: NaNO3-KNO2-N2O-N2H4-NH2OH
  1. Calculate the mass percentage of nitrogen in the following compounds. (N:14, C:12, S:32, O:16, H:1, Cl:35.5)

     a) NH4Cl b) NH4ClO3 c) (NH4)2S d) (NH4)2SO4 e)NH4NO3

  • Write the decomposition reactions of the following ammonium salts:

     NH4Cl, NH4ClO3, (NH4)2S,(NH4)2SO4, (NH4)3PO4,NH4NO3

  • How many liters of ammonia is needed with 10L of 2M H2SO4 to produce ammonium sulfate?
  • When 5grams of ammonia and 5g hydrochloric acid reacts together, how many grams of products can be obtained? Which reactant will be excess and how many grams?
  • Write the reactions of nitric acid and find the moles of nitric acid for 10 grams of

     a) iron(III) oxide b) zinc hydroxide c) Calcium carbonate

  1. 6 mol of the mixture NH3-O2 is burned. After the reaction, the total mol number of substances in container is found to be 7.5mole. Write the equation of the reaction. Which reactant is limited reagent? Find the moles and types of substances in container.
  2. 5g of ammonia treated with 1L 1M hydrochloric acid. How many grams of product can be obtained?
  3. There are 9.8 grams of nitrogen in the structure of 26.6 grams of an unknown nitrogen oxide. What is the simplest formula of this compound?
  4. How is the nitrogen oxide formed? Write the reactions.
  • Complete the following reactions:

     Fe(OH)3 + HNO3 ®
     MgO + HNO3 ®

    • How can we prepare following compounds at laboratory?                            NO-N2O-NO2-N2

    CARBON FAMILY

    • Carbon is group 4 element. In this group 4 there are carbon (C) silicon(Si), germanium(Ge), tin(Sn) and lead(Pb).
    • Carbon is a nonmetal, the next two members are metalloids (Si-Ge), tin and lead are metals.
    • Electron configuration of this group ends with ns2np2.
    • Their compounds have -4, +2 and +4 oxidation states.
    • Tin has three allotropes; white, grey and rhombic tin.

    General Properties of Carbon

    • Carbon has an atomic number 6 and its electron configuration is 1s22s2sp2.
    • Carbon has three isotopes:12C, 13C and 14C.
    • Carbon has two allotropes, graphite and diamond.
    • Carbon is a nonmetal.
    • It takes oxidation states between -4 and +4.(C-CO2-CO-CH4-HCN)
    • Carbon is the basic element of living organisms.
    • There is enormous number of carbon compounds when compared with other elements.
    • Carbon is found as natural gas, petroleum and its by-products.

    Reactions of Carbon
    1. Reaction with metals
    It reacts with metals to produce carbide salts.
    2Mg + C ® Mg2C magnesium carbide
    4Al + 3C ® Al4C3 aluminum carbide

    2. Reaction with nonmetals
    C + 2S ® CS2
    C + H2 ® CH4

    3. Reaction with bases and basic oxides
    C + CuO ® CO + Cu (limited)
    C + 2CuO ® CO2 + 2Cu (excess)

    4. Reaction with acids:
    C  +  2 H2SO4  ®  CO2  +  2 SO2  +  2 H2O (Hot and concentrated)
    C  +  4 HNO3   ®  CO2  +  4 NO2  +  2 H2O (Hot and concentrated)

    5. Combustion reactions                                 
    2C + O2 ® 2 CO (Less amount of oxygen )
    C + O2 ® CO2  (Excess amount of oxygen )

    6. Reactions with halogens
    Carbon does not react directly with halogens, except fluorine.
    C + F2 ® CF4   carbon tetra fluorine used as Teflon  

    Compounds of Carbon
    1. Oxides
    a) Carbon monoxide (CO)

    • CO is a colorless, odorless and poisonous gas.
    • Carbon monoxide is found in the atmosphere in trace amounts.
    • The exhausts gas of motor cars and the combustion of fuel cause an increase in the concentration of carbon monoxide in air.
    • Carbon monoxide is neither acidic nor basic. It is a neutral oxide.

    Reactions of Carbon Monoxide
    1. It reduces metal oxides to metals.
    ZnO + CO ® Zn + CO2
    2. CO also reduces steam to hydrogen at 230 0C
    CO + H2O ® H2 + CO2
    3. It burns in air with a faint blue flame.
    2CO + O2 ® 2CO2
    4. CO reacts with chlorine to form phosgene gas.
    CO + Cl2 ® COCl2 phosgene
    5. Carbon monoxide does not react with water.
    CO + H2O ® no rxn

    b) Carbon dioxide (CO2)

    • It is a colorless, odorless and nonpoisonous gas.
    • To check the presence of CO2 in the media Ca(OH)2 can be used CaCO3 precipitation proves the presence of CO2.

    CO2 + Ca(OH)2 ® CaCO3 + H2O
    CaCO3 + H2CO3 ® Ca(HCO3)2 an acidic salt, soluble in water
            

    Reactions of Carbon Dioxide
    1. Reaction with water
    CO2 + H2O ® H2CO3 carbonic acid
    2. Reaction with basic oxides and bases
    CO2 + CaO ® CaCO3
    CO2 + 2NaOH ® Na2CO3 + H2O

    2. Carbonic Acid (H2CO3)

    • Carbonic acid is a weak and unstable acid.
    • It is diprotic acid:

    H2CO3 ® H+ + HCO3-
    HCO3 ® H+ + CO32-
            

    Reactions of Carbonic Acid
    1. Reaction with active metals
    H2CO3 + Ca ® CaCO3 + H2
    2. Reaction with metal oxides
    H2CO3 + MgO ® MgCO3 + H2O
    3. Reaction with bases
    H2CO3 + 2NaOH ® Na2CO3 + 2H2O if H2CO3 excess:
    H2CO3 + NaOH ® NaHCO3 + H2O
    4. Decomposition reaction
    H2CO3 ® CO2 + H2O

    3. Carbonate Salts
    Na2CO3 : sodium carbonate
    NaHCO3 : sodium bicarbonate

             Reactions of Carbonate Salts
    1. Reaction with salts
    Na2CO3 + CaCl2 ® 2NaCl + CaCO3
    2. Reaction with acids
    Na2CO3 + 2HCl ® H2CO3 (H2O + CO2) + 2NaCl
    3. Reaction with carbonic acid
    Na2CO3 + H2CO3 ® 2NaHCO3

    Ex:MgCl2 ® MgCO3 ® Mg(HCO3)2 ® MgCO3 ® CO2 ® Na2CO3
    MgCl2 + H2CO3 ® MgCO3 + 2HCl
    2MgCO3 + H2CO3 ® 2Mg(HCO3)
    Mg(HCO3)2 ® MgCO3 + H2O + CO2
    MgCO3 ® MgO + CO2
    CO2 + Na2O ® Na2CO3

     

 

© 2007 by Ali Uysal Teacher of Chemistry