Question

Classify each acid as strong or weak. If the acid is weak, write an expression for the acid ionization constant (Ka). If the acid is polyprotic, classify both ionizations.

a. HF

b. HNO3

c. H2CO3

Answer 1

Following is the - complete Answer -&- Explanation: for the given: Question: in......typed format....

Answer:

(a): HF is a Weak Acid.

(b): HNO₃ is a Strong Acid.  

(c): H₂CO₃  is a Weak Acid.

Explanation:

Following is the complete Explanation, for the above Answers.

• Step - 1:

Hydrofuoric Acid ( HF ) , is a Weak Acid. This implies, that the aqueous solution of Hydrofluoric acid ( HF ), doesn't completely dissociate, in to ions, readily. Following are the details, requested:

HF (aq) + H₂O (l) H₃O⁺ (aq) + F ^- (aq) ----------------------Equation - 1

Expression of the acid dissociation / ionization constant, will be the followwing:

K_a = [F^- ] x [H₃O⁺] / [HF]   ---------------------------Equation - 2

Where:  

1. [F^- ] = Molar concentration of Fluoride ion, ( mol/L ) at Equilibrium.
2. [H₃O⁺] = Molar concentration ( mol/L ) of Hydronium ion, at Equilibrium.
3. [HF] = Molar concentration of Hydrogen fluoride ( mol/L ) , at Equilibrium.

• ​​​​​​​Step - 2:

​​​​​​​As we have mentioned, Nitric acid ( HNO₃ ), has the aqueous solution, which gets completely, and readily soluble in Water.

Therefore, nitric acid, is a strong acid.

• Step - 3:

​​​​​​​As we know, Carbonic acid ( H₂CO₃) , is an example of a Weak acid. This is because, the aqueous solution of Carbonic acid, doesn't get completely dissociated/ ionized, readily.

Following are the details, requested:

For the initial/ first ionic dissociation:

Balanced Ionic equation of dissociation:

H₂CO₃ (aq)    H⁺ (aq) + HCO₃^- (aq)   -----------------------Equation - 3

Expression of first acid dissociation constant:

K_a1 = [ HCO₃^- ] x [ H⁺] / [ H₂CO₃ ]

• Step - 4:

​​​​​​​For the second ionic dissociation/ ionization:

Balanced Ionic equation of dissociation:

HCO₃^- (aq)    H⁺ (aq) + CO₃^2- (aq)   -----------------------Equation - 4

Expression of second acid dissociation constant:

K_a2 = [ CO₃^2- ] x [ H⁺] / [ HCO₃^- ] -------------------Equation - 5

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