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Chemical properties

1. Interaction with basic oxides with formation of salts and water:

2HNO3 + CuO = Cu(NO3)2 + H2O;

3H2SO4 + Fe2O3 = Fe2(SO4)3 + 3H2O;

2. Interaction with amphoteric oxides with formation of salts and water:

2HCl + ZnO = ZnCl2 + H2O;

6HClO4 + Al2O3 = 2Al(ClO4)3 + 3H2O;

3. Interaction with bases with formation of salts and water:

H2CO3 + Ca(OH)2 = CaCO3 + 2H2O;

2H3PO4 + 3Mg(OH)2 = Mg3(PO4) 2 + 6H2O;

4. Interaction with amphoteric hydroxides with formation of salts and water: 2HNO3 + Pb(OH)2 = Pb(NO3)2 + 2H2O;

3H2SO4 + 2Cr(OH)3 = Cr2(SO4)3 + 6H2O;

5. Interaction with metals (Red Ox reactions):

Zn + 2HCl = ZnCl2 + H2 ­;

3Cu + 8HNO3 = 3Cu(NO3)2 + 2NO ­ + 4H2O;

6. Interaction of weaker acid salts (metathesis or exchange reaction):

FePO4 + 3HNO3 = Fe(NO3)3 + H3PO4;

H2SO4 + BaCl2 = BaSO4 + 2HCl.

 

 

Amphoteric hydroxides

 

Amphoteric hydroxides are the hydrated forms of amphoteric oxides having weak basic and acidic properties.

Preparation

1. Interaction with acidic oxides forming salts and water (amphoteric hydroxides show properties of bases):

Zn(OH)2 + N2O5 = Zn(NO3)2 + H2O;

2Cr(OH)3 + 3SO3 = Cr2(SO4)3 + 3H2O.

2. Interaction with acids forming salts and water (amphoteric hydroxides show properties of bases):

Zn(OH)2 + 2HNO3 = Zn(NO3)2 + 2H2O;

2Cr(OH)3 +3H2SO4 = Cr2(SO4)3 + 6H2O.

3. Interaction with basic oxides forming salts and water (amphoteric hydroxides show properties of acids):

for Zn(OH)2: H2ZnO2 + Li2O = Li2ZnO2 + H2O

for Cr(OH)3 : 2HCrO2 + BaO = Ba(CrO2)2 + H2O or

2H3CrO3 + 3BaO = Ba3(CrO3)2 + 3H2O;

4. Interaction with bases forming salts and water (amphoteric hydroxides show properties of acids):

for Zn(OH)2: H2ZnO2 + 2LiOH = Li2ZnO2 + 2H2O

for Cr(OH)3: 2HCrO2 + Ba(OH)2 = Ba(CrO2)2 + 2H2O or

2H3CrO3 + 3Ba(OH)2 = Ba3(CrO3)2 + 6H2O;

Depending on series of chemical reaction, names of amphoteric hydroxides are changed. For example, Zn(OH)2 in reactions with acidic oxides and acids must be referred to “Zinc hydroxide”, while in reactions with basic oxides and alkalis - “Zinc acid” (see Appendix 4).

 

Salts

Salts - complex substances, which consist of metal atoms and acid residuals. This is a most multiple class of inorganic compounds. Sometimes salts may include positive charged group of atoms (for example, NH4+).

Classification of salts:

Varieties Characteristics Examples
Neutral (normal) Include atoms of metal (or ionic group NH4+) and acid residue. Products of full substitution of Hydrogen atoms in acids to metal atoms NaCl, Ca3(PO4)2, K3AlO3
Basic Include atoms of metal (or ionic group NH4+), hydroxyl OH- and acid residue. Products of incomplete substitution of OH-groups of multi-acidic bases into acid residue ZnOHCl, (MgOH)2SO4, (MgOH)3PO4, FeOHBr2
Acidic Include atoms of metal (or ionic group NH4+), ion H+ and acid residue. Products of incomplete substitution of H+ of multi-basic acids into atoms of metal or NH4+ NaHCO3, NH4H2PO4, Ca(H2PO4)2, KHSO4
Double Include atoms of two different metals and acid residue NaKSO4, KAl(SO4)2, NH4Cr(SO4)2.
Mixed Include atoms of metal and two different acid residues CaCl(ClO)
Complex Contain complex cations or anions [Ag(NH3)2]Cl, Na3[Co(NO2)6]

 

Salts are entitled starting from the name of corresponding metal and acid residue (See Appendix 4). For example, Ca3(PO4)2 - Calcium OrthoPhosphate, NaNO3 - Sodium Nitrate, KHSO4 - Potassium HydroSulfate, FeOHCl2 - Iron (III) Hydroxy Chloride etc.

A few salts and chemical compounds or mixes have common names as household (domestic) chemicals or technical reactants. Sometimes names of such chemicals were given by Alchemists in great antiquity (for example, BaSO4 (Barium Sulfate) - Heavy Spar, Aqua-regia - Mixture of conc. HNO3 (1 volume) and conc. HCl (3 volumes) etc. (See Appendix 12).

 

Preparation

There are known a lot of methods for salts’ preparations. The typical ones are mentioned below:

1. Interaction between metals and non-metals (Sulfur, Halogens):

Zn + S = ZnS

2Bi + 3Cl2 = 2BiCl3;

2. Interaction between salts and metals (according to relative activity of Metals, see Appendix 11):

CuSO4 + Fe = FeSO4 + Cu;

Pb(NO3)2 + Zn = Zn(NO3)2 + Pb;

3. Interaction between some salts and non-metals:

2FeCl2 + Cl2 = 2FeCl3;

2Na2SO3 + O2 = 2Na2SO4;

4. Interaction between basic oxides and acidic oxides:

CaO + CO2 = CaCO3;

3Na2O + P2O5 = 2Na3PO4;

5. Interaction between acids and basic oxides:

H2SO4 + MgO = MgSO4 + H2O;

6HCl + Fe2O3 = 2FeCl3 + 3H2O;

6. Interaction between bases and acidic oxides:

Ba(OH)2 + SO2 = BaSO3 + H2O;

2Fe(OH)3 + 3N2O5 = 2Fe(NO3)3 + 3H2O;

7. Interaction between acids and bases:

HNO3 + NaOH = NaNO3 + H2O;

H3PO4 + 3KOH = K3PO4 + 3H2O;

8. Interaction between stronger acids and salts of weaker acids:

H2SO4 + K2SiO3 = K2SO4 + H2SiO3;

HBr + AgNO3 = AgBr + HNO3;

9. Interaction between alkalis and salts:

2LiOH + CuCl2 = Cu(OH)2 + 2LiCl;

Ca(OH)2 + NiSO4 = CaSO4 + Ni(OH)2;

10. Interaction between two different salts (metathesis reaction):

2AgNO3 + CaI2 = 2AgI + Ca(NO3)2;

Cr2(SO4)3 + 3BaCl2 = 2CrCl3 + 3BaSO4.

 

Chemical properties

1. Interaction with some of the acids with the formation of other salt and acid:

BaCl2 + H2SO4 = BaSO4 + 2HCl;

Na2S + H2SO4 = Na2SO4 + H2S;

2. Interaction with alkalis with the formation of other salt and base:

NiSO4 + 2KOH = Ni(OH)2 + K2SO4;

2FeCl3 + 3Ba(OH)2 = 2Fe(OH)3 + 3BaCl2;

3. Interaction with more active metals:

Zn + CuSO4 = ZnSO4 + Cu;

Cu + Hg(NO3)2 = Cu(NO3)2 + Hg;

4. Some salts may react with each other forming two new salts:

Ba(NO3)2 + K2CO3 = BaCO3 + 2KNO3;AlCl3 + 3AgNO3 = Al(NO3)3 + 3AgCl.

Date: 2015-01-12; view: 1395

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