Home Random Page


CATEGORIES:

BiologyChemistryConstructionCultureEcologyEconomyElectronicsFinanceGeographyHistoryInformaticsLawMathematicsMechanicsMedicineOtherPedagogyPhilosophyPhysicsPolicyPsychologySociologySportTourism






Ionic equations

 

Double replacement reactions and other reactions of ions in aqueous solution are usually represented by that are known as “net ionic equations”. To write a net ionic equation, one firstly writes an equation in which all strong electrolytes are shown as dissociated ions in solution (without steps, of course). For example:

1. Formation of slightly soluble substance:

CuSO4 + 2NaOH = Cu(OH)2¯ + Na2SO4

Cu2+ + SO42- + 2Na+ + 2OH- = Cu(OH)2¯ + 2Na+ + SO42- -

this is a complete ionic equation.

Cu2+ + 2OH- = Cu(OH)2¯ - this is net ionic equation.

2. Formation of weak electrolyte:

a) HCl + KOH = KCl + H2O,

H+ + Cl- +K+ + OH- = K+ + Cl- + H2O,

H+ + OH- = H2O.

b) ÑH3COONa + HCl = CH3COOH + NaCl,

CH3COO- + Na+ + H+ + Cl- = CH3COOH + Na+ + Cl-,

CH3COO- + H+ = CH3COOH.

3. Formation of gas:

à) K2CO3 + 2HNO3 = 2KNO3 + CO2­ + H2O,

2K++ CO32- + 2H+ + 2NO3- = 2K+ + 2NO3- + CO2­ + H2O,

CO32- + 2H+ = CO2­ + H2O.

b) FeS + 2HCl = FeCl2 + H2S­.

Iron (II) Sulfide is slightly soluble and Hydrogen Sulfide is a weak electrolyte (gas). Therefore:

FeS + 2H+ + 2Cl- = Fe2++ 2Cl- + H2S­,

FeS + 2H+ = Fe2++ H2S­.

Interactions in the solutions of electrolytes are realized completely if in the result the following will be formed:

à) weak electrolyte;

á) sediments;

â) gases.

 

PRACTICE PROBLEMS

1. Write the dissociation equation for the ions of the following compounds:

H2SO4, HClO4, Ca(OH)2, AlCl3, Fe2(SO4)3, K2CO3, Bi(NO3)3, Na2HPO4, NH4HCO3, Co(NO3)3.

2. Write molecular, complete and net ionic equations:

Ø BaCl2 + Fe2(SO4)3

Ø Cu(NO3)2 + Na2CO3

Ø Na2SiO3 + H2SO4

Ø FeCl3 + KOH →

Ø H3PO4 + Ba(OH)2

Ø Cu(OH)2 + HCl →

Ø Na2HPO4 + CaCl2

3. Which of two reactions does proceed in the solution up to the end and why? Draw the corresponding molecular, complete and net ionic equations:

Ø Calcium Chloride + Magnesium Nitrate →

Ø Sodium Carbonate + Zinc Chloride →

Ø Lithium Sulfate + Potassium hydroxide →

Ø Iron (II) Sulfate + Sodium hydroxide →

Ø Iron (III) hydroxide + Nitric Acid →

4. Draw molecular equations of the reactions between substances interacted in aqueous solution according to the following scheme:

Ø Ba2+ + SO42- → BaSO4;

Ø Fe(OH)3 + 3H+ → Fe3+ + 3H2O;

Ø CaCO3 + 2H+ → Ca2+ + CO2 + H2O;

Ø 3Mg2+ + 2PO43- → Mg3(PO4)2;

Ø Ca2+ + 2 F- → CaF2.

 


Date: 2015-01-12; view: 775


<== previous page | next page ==>
Theory of dissociation | HYDROLYSIS OF SALTS
doclecture.net - lectures - 2014-2024 year. Copyright infringement or personal data (0.007 sec.)