# Problem: Ammonium iodide can dissociate to produce HI and ammonia, NH4I(s) ⇌ NH3(g) + HI(g). At 300 °C, Kp = 0.42. If 250. g of ammonium iodide is placed into a 3.00 L flask and heated to 300 °C, what is the partial pressure of ammonia at equilibrium?a. 0.84 atm b. 0.21 atmc. 0.42 atmd. 0.65 atme. 0.18 atm

###### FREE Expert Solution

We’re being asked to determine the partial pressure of Ammonia when 250 g of NH4I is placed in a 3 L flasked heated up to 300°C

NH4I(s)  NH3(g) + HI(g)

Recall that the equilibrium constant is the ratio of the products and reactants.  We use Kp when dealing with pressure and Kc when dealing with concentration:

$\overline{){{\mathbf{K}}}_{{\mathbf{p}}}{\mathbf{=}}\frac{{\mathbf{P}}_{\mathbf{products}}}{{\mathbf{P}}_{\mathbf{reactants}}}}$     $\overline{){{\mathbf{K}}}_{{\mathbf{c}}}{\mathbf{=}}\frac{\mathbf{\left[}\mathbf{products}\mathbf{\right]}}{\mathbf{\left[}\mathbf{reactants}\mathbf{\right]}}}$

Note that solid and liquid compounds are ignored in the equilibrium expression. ###### Problem Details

Ammonium iodide can dissociate to produce HI and ammonia, NH4I(s) ⇌ NH3(g) + HI(g). At 300 °C, Kp = 0.42. If 250. g of ammonium iodide is placed into a 3.00 L flask and heated to 300 °C, what is the partial pressure of ammonia at equilibrium?

a. 0.84 atm

b. 0.21 atm

c. 0.42 atm

d. 0.65 atm

e. 0.18 atm