Write the chemical reaction that is responsible for the pH of a buffer which contains NH3 and NH4Cl. Write the reaction in such a way that is appropriate for a Ka.
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NH3 + H2O <--> NH4+ + OH- Ka = [NH4+][OH-]/[NH3]
To determine the chemical reaction responsible for the pH of a buffer containing NH3 (ammonia) and NH4Cl (ammonium chloride), we need to consider the equilibrium between NH3 and NH4+ ions in water.
The equilibrium equation for the reaction is:
NH4+ (aq) + H2O (l) ⇌ NH3 (aq) + H3O+ (aq)
In this equation, NH4+ represents the ammonium ion, NH3 represents ammonia, and H3O+ represents the hydronium ion (which determines the pH).
To make this equation suitable for a Ka (acid dissociation constant), we can rewrite it by considering the reaction as the dissociation of NH4+ as an acid and the subsequent formation of NH3 by accepting a hydrogen ion:
NH4+ (aq) ⇌ NH3 (aq) + H+ (aq)
Now, the equation is appropriate for a Ka because we have separated NH4+ into NH3 and H+ ions.
It is important to note that the NH4Cl buffer acts as a source of NH4+ ions, which can accept hydrogen ions (H+) to form NH3. The NH3 then combines with water to produce fewer free H+ ions, helping to maintain the pH of the buffer solution.
The chemical reaction responsible for the pH of a buffer containing NH3 (ammonia) and NH4Cl (ammonium chloride) can be represented as follows:
NH3 + H2O ⇌ NH4+ + OH-
This reaction involves the base NH3 accepting a proton (H+) from water, leading to the formation of the conjugate acid NH4+ and hydroxide ions (OH-). In terms of Ka, the reaction can be written as:
NH4+ + H2O ⇌ NH3 + H3O+
Here, NH4+ acts as the conjugate acid, and H3O+ represents the hydronium ion. This equation represents the ionization of NH4+ into NH3 and H3O+ in an aqueous solution.