شرح درس
Chemical Equation
CHEMISTRY - Secondary 1
In This part we will study
Ionic equations can be used to represent some :

(1) Physical processes, Such as :
Dissociation of the molecules of some ionic substances
when they:
• Thermally decomposed.
• Dissolved in water.

Application :
The ionic equation which represents dissolving of sodium chloride salt in water :
NaCl(s) → Na+(aq) + Cl-(aq)
Sodium Hydrated Hydrated
chloride sodium ion chloride ion

(2) Chemical reactions, Such as :
Neutralization reactions.  Precipitation reactions.

 The ionic equation for neutralization reactions
The reaction of acid and base to form salt and water is called "Neutralization reactions"
Because the properties of acid and base disappear when they react together.

Example (1) :
The reaction between sulphuric acid and sodium hydroxide is represented by the following symbolic equation :
H2SO4(aq) + 2NaOH(aq) → Na2SO4(aq) + 2H2O(l)
But , does this equation represent the real form of the substances in the aqueous solution ?
Many substances like (acids - bases - salts) are ionized in water. So, the equation should be written as the following :


From the previous equation :
The sodium ions Na+(aq) and sulphate ions SO4(aq) remained free and didn't participate in the reaction. So , they can be cancelled from the both sides of the equation. So, the ionic equation of this reaction will be written as :
2H+(aq) + 2OH-(aq) → 2H2O(l)
The ionic equation of any neutralization reaction will be :
H+(aq) + OH-(aq) → H2O(l)
Example (2) :
Write the net ionic equation which represents the neutralization reaction of an aqueous solution of hydrochloric acid with an aqueous solution of sodium hydroxide.
Solution :

 Ionic equation which represents precipitation reactions
Chemical reactions that occur between aqueous solutions of two different (soluble) salts and give (produce) solid salts insoluble in water (precipitates) are called "Precipitation reactions"

Example (1) :
On adding potassium chromate solution to silver nitrate solution, a red precipitate of silver chromate is formed which is insoluble in water.
K2CrO4(aq) + 2AgNO3(aq) → 2KNO3(aq) + Ag2CrO4(s)
(red precipitate)
The equation should be written as the following ionic form :

From the previous equation :
"2" 〖"Ag" 〗_"(aq)" ^"+" + 〖"CrO" 〗_(4 (aq))^(2-)→ 〖"Ag" 〗_"2" 〖"CrO" 〗_"4(s)"

Example (2) :
Write the ionic equation for the following precipitation reaction.


Best wishes to you
Mr.Ahmed Elbasha

كيمياء الصف الاول الثانوي لغات - الفصل الدراسي الاول
شرح كيمياء لغات اولي ثانوي - مستر احمد الباشا
كيمياء لغات - الصف الاول الثانوي - كيمياء اولي ثانوي الترم الاول - كيمستري اولي ثانوي الترم الاول