Calculate the concentration of buffer components present in 293.00 mL of a buffer solution that contains 0.430 M NH4Cl and 0.430 M NH3 immediately after the addition of 1.60 mL of 6.00 M HNO3.

Answer 1

Initial moles NH₃ = 0.29300 L x 0.430 mol/L = 0.12599 moles NH₃

Initial moles NH₄⁺ = 0.29300 L x 0.430 mol/L = 0.12599 moles NH₄⁺

Moles H⁺ added = 0.00160 L x 6.00 mol/L = 0.0096 moles H⁺

Addition of HNO₃ to the buffer will react with the NH₃ to produce NH₄⁺

NH₃ + H⁺ ==> NH₄⁺

0.12599...0.0096..........0.12599..........Initial

-0.0096....-0.0096.......+0.0096...........Change

0.11639.....0................0.13599...........Equilibrium

Final volume = 293.00 ml + 1.60 ml = 294.60 ml = 0.29460 L

Final concentration of buffer components is as follows:

[NH₃] = 0.11639 mol / 0.29460 L = 0.39508 M

[NH₄⁺] = 0.13599 mol / 0.29460 L = 0.46161 M