0.214 mol AgNO3 and 3.58 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) = 1.50 x 10^7 at 25 °C.

Respuesta :

Answer:Equilibrium concentration of free silver ion is 3.21×10^6 mol

Explanation: Since we have enough water in the reaction, we have aqueous NH3 reacting with AgNO3 (aq)

Equation of reaction:

AgNO3(aq) + 2NH3(aq) <----> Ag(NH3)2+ at 25°C

Formation of complexes is also a thermal dynamic phenomenon. For the equilibrium,

Ag+ + 2NH3 <----> Ag(NH3)2+

AgNO3(aq) + 2NH3(aq) <----->Ag+ + 2NH3(aq)

•From the question, we have 0.214 mol of AgNO3 reacting with 3.58mol NH3 to produce a solution containing Ag(NH3)2+

•We can relate the number of moles to say that since we have 2 moles of NH3 reacting to form 2 moles of NH3 as product,

•Therefore 3.58mol of NH3 produces 3.58 mol of NH3 as well

AgNO3+ 2NH3 <----> Ag+ + 2NH3

0.214mol 3.58mol 3.58mol

We can calculate the equilibrium concentration of free Ag+

Kf= [Ag+] [NH3]^2 / [AgNO3] [NH3]^2

Since we have [NH3]^2 as numerator and denominator we can easily cancel out both, leaving

Kf= [Ag+] / [AgNO3]

cross multiply

[Ag+] = Kf × [AgNO3]

Kf is given as 1.50× 10^7 at 25°C

Substitute into equation we have

[Ag+]= 1.50×10^7 × 0.214mol

[Ag+]= 3.21×10^6mol

Equilibrium concentration of free silver ion is 3.21×10^6 mol

Based on the data provided, the equilibrium concentration of free silver ion [ Ag⁺ ] in the solution is 1.43 × 10^9 M

What is equilibrium concentration of a substance?

The equilibrium concentration of a substance is the concentration of that substance when it has achieved equilibrium.

From the data provided, equilibrium concentration of free silver ion can be calculated as follows:

0.214 mol of AgNO₃ was added

2.73 mol NH₃ was also added

Temperature = 25°C

Volume of solution = 1.00 L

Since Kf is very high, reactants get converted to product before equilibrium is attained.

The equilibrium concentration of  [Ag+] is determined from the equation for the reaction at equilibrium:

  • Ag⁺ + 2NH₃ ⇄ Ag(NH₃)₂⁺

Initially:

[Ag⁺] = 0.214 - 0.214 = 0

[Ag(NH₃)₂⁺] = 0 + 0.214 = 0.214

[NH₃] =  3.58 mol - 2 × 0.214 = 3.152

At equilibrium:

[Ag⁺]  = X

[Ag(NH₃)₂⁺] = 0.214 - X

[NH₃] = 3.152 + X

kf = 1.5 * 10⁷ =  [Ag(NH₃)₂⁺]  /  [NH₃]² [Ag⁺]

1.50 * 10⁷ =  (0.214 - X) / ( 3.152 + X)² × (X)

assuming X to be very small:

  • 0.214 - X = 0.214;
  • 3.152 - X = 3.152

Then;

1.50 * 10⁷ =  (0.214) / (3.152)² × (X)

solving for X;

X = 7.09 × 10⁻⁷ M

Therefore, the equilibrium concentration of [ Ag⁺ ] is 1.43 × 10^-9 M

Learn more about equilibrium concentration at: https://brainly.com/question/26515535

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