0.398 mol AgNO3 and 2.73 mol NH3 were added to enough water to give 1.00 L of solution at 25 °C. Calculate the equilibrium concentration of free silver ion , [Ag+], in this solution. The formation constant for Ag(NH3)2+ (Kf) = 1.50x107 at 25 °C.

[Ag⁺] = 1x10⁻⁸M

Explanation:

In the reaction:

Ag⁺ + 2NH₃ ⇄ Ag(NH₃)₂⁺

Kf = 1.50x10⁷ =  [Ag(NH₃)₂⁺] / [NH₃]²[Ag⁺]

If in the beginning you add 0.398 moles of Ag⁺ and 2.73 moles of NH₃. Concentrations in equilibrium are:

[Ag(NH₃)₂⁺]: X

[NH₃]: 2.73mol - 2X

[Ag⁺]: 0.398mol - X

Replacing:

1.50x10⁷ =  [X] / [2.73-X]²[0.398-X]

1.50x10⁷ =  [X] / (7.4529-5.46X+X²)(0.398-X)

1.50x10⁷ =  [X] / 2.9662542-9.62598X+5.858X²-X³

-1.50x10⁷X³+8.787x10⁷X²-1.443897x10⁸X + 4.4493813x10⁷ = X

-1.50x10⁷X³+8.787x10⁷X²-1.443897x10⁸X + 4.4493813x10⁷ = 0

Solving for X:

X = 0.39799999

Thus, equilibrium concentration of Ag⁺, [Ag⁺] is 0.398mol - X. Replacing:

[Ag⁺] = 0.398mol - 0.39799999 = 1x10⁻⁸M

both adhesion and cohesion are attractions.

they are different in that adhesion is the force of attraction between the molecules of two different substances, whereas cohesion is the force of attraction between molecules of the same substance.

possible examples include capillary action, in which the adhesion between water and glass causes the water to rise in a narrow tube against the force of gravity.

because of hydrogen bonding, water is extremely cohesive.

this causes molecules on the surface of water to be drawn inward, which is why drops of water form beads on smooth surfaces.

hope this .