"What is the hydronium ion concentration in a 0.100-M solution of ammonium nitrate, NH4NO3, a salt composed of the ions NH4 + and NO3 −." Which is the stronger acid C6 H5 NH3 + or NH4 + ?

A.  [H₃O⁺] = 7.4 * 10⁻⁶

B. C₆H₅NH₃⁺ is the stronger acid

Explanation:

A. Ammonium nitrate,  NH₄NO₃ dissolves in solution to form ammonium ions  NH₄⁺ which act as a weak acid by protonating water to form ammonia,  NH₃ (aq) and hydronium ions  H₃O⁺(aq) :  NH₄⁺ (aq) + H₂O (l) →  H₃O⁺(aq) + NH₃(aq)

Using the acid dissociation formula, Ka (NH₄⁺) = [NH₃] [H₃O⁺] / [NH₄⁺ ] where Ka of NH₄⁺ = 5.6 * 10⁻¹⁰, [NH₄⁺ ] = 0.100 M,

Let [NH₃] = x, and [H₃O⁺] = x; since one molecule of hydronium ion must form for every one of ammonia that forms. The assumption is also made that x << than 0.1 M due to the small Ka.

5.6 * 10⁻¹⁰ = [x] [x]  / 0.1

[x]² = 5.6 * 10⁻¹¹

[x] = 7.4 * 10⁻⁶

Therefore, [H₃O⁺] = 7.4 * 10⁻⁶

B. The strength of an acid is measured by its dissociation constant, Ka, which can also be expressed as pKa. Where pKa = -log₁₀Ka

The higher the value of an acid's dissociation constant, Ka, (or the lower its pKa) the stronger the acid.

The dissociation constants Ka, as well as pKa of C₆H₅NH₃⁺ and NH₄⁺ are given below:

C₆H₅NH₃⁺ :   Ka = 1.3 * 10⁻⁵; pKa = 4.87

NH₄⁺ : Ka = 5.6 * 10⁻¹⁰; pKa = 9.25

From the above, it can be seen that C₆H₅NH₃⁺  has a  higher Ka than NH₄⁺, therfore, it is the stronger acid.

answer: the rate of diffusion increases with increase in temperature.

increase in temperature, increases the molecular/particles speed (kinetic energy. diffusion means movement of particles through the material.

generally, the heavier the particle the more it interacts with the environment and more the temperature matters. so higher temperature results in higher diffusion.

a