A student place 7 moles of ammonia (NH3) in a 100 ml flask with 50 ml deionized water. At equilibrium, 0.2M (NH4+) was found in a flask. What is the mole of ammonium (NH4+) at the equilibrium?

Answer 1

To find the number of moles of ammonium \( \text{NH}_4^+ \) at equilibrium, we can use the concentration and the volume of the solution.

Given:

• The equilibrium concentration of \( \text{NH}_4^+ \) is \( 0.2 , M \).
• The volume of the solution is \( 100 , \text{ml} + 50 , \text{ml} = 150 , \text{ml} \) or \( 0.150 , \text{L} \).

To calculate the moles of \( \text{NH}_4^+ \) at equilibrium, use the formula:

\[ \text{Moles} = \text{Concentration} \times \text{Volume} \]

Substituting the known values:

\[ \text{Moles of } \text{NH}_4^+ = 0.2 , \text{mol/L} \times 0.150 , \text{L} = 0.03 , \text{moles} \]

Therefore, the number of moles of ammonium \( \text{NH}_4^+ \) at equilibrium is 0.03 moles.