He hydroxide ion concentration in household ammonia is 3.2 × 10−3 m at 25 °c. what is the concentration of hydronium ions in the solution

Respuesta :

when Kw = [OH-][H3O+] ,

and when Kw is the ionic constant for water at 25°C = 1 x 10^-14

 and we have [OH-] = 3.2 x 10^-3

 this the concentration at equilibruim.

so by substitution:

 1 x 10^-14 = 3.2 x 10^-3 * [H3O+] .

 [H3O] = (1 x 10^-14) / (3.2 x 10^-3)

              = 3.125 x 10^-12 m.

 so, the answer is: concentration of hydronium ions is = 3.125·10⁻¹² M

Answer:- [tex][H_3O^+]=4.2*10^-^1^1[/tex]

Solution:- Ammonia is a weak base. So, to calculate the hydroxide ion concentration we make the ice table:

   [tex]NH_3(aq)+H_2O(l)\rightleftharpoons NH_4^+(aq)+OH^-(aq)[/tex]

I            0.0032                                                    0                  0

C             -X                                                          +X               +X

E      (0.0032-X)                                                    X                 X

[tex]K_b=\frac{[NH_4^+][OH^-]}{[NH_3]}[/tex]

Kb value for ammonia is [tex]1.8*10^-^5[/tex] . Let's plug in the values and solve for X.

[tex]1.8*10^-^5=\frac{X^2}{0.0032-X}[/tex]

Kb value is very low so we can neglect the X on the bottom.

[tex]1.8*10^-^5=\frac{X^2}{0.0032}[/tex]

On cross multiply:

[tex]X^2=1.8*10^-^5*0.0032[/tex]

[tex]X^2=5.76*10^-^8[/tex]

On taking square root:

[tex]X=2.4*10^-^4[/tex]

From ice table, [tex][OH^-]]=X[/tex]

So, [tex][OH^-]=2.4*10^-^4[/tex]

hydronium ion and hydroxide ion concentrations are related to each other by the formula:

[tex][H_3O^+][OH^-]=K_w[/tex]

where, Kw is the water dissociation constant and its value is [tex]1.0*10^-^1^4[/tex]

[tex][H_3O^+]=\frac{1.0*10^-^1^4}{2.4*10^-^4}[/tex]

[tex][H_3O^+]=4.2*10^-^1^1[/tex]