40 ~mL of 0.1 M ammonia solution is mixed with 20 ~mL of 0.1 MHCl . What is the pH of the mixture? ( p K_b of ammonia solution is 4.74)

Step-by-step solution

40 ~mL of 0.1 M ammonia solution =40 0.1=4 milliequivalent ammonia solution 20 ~mL of 0.1 M HCl =20 0.1=2 milli equivalent of HCl array lccc & NH ₄ OH + & HCl NH ₄ Cl + H ₂ O Initial milli-eqv. & 4 & 2 & 0 Milli-eqv. after & 4-2 & 0 & 2 reaction & =2 & & array gathered pOH = pK K_b+ [ NH ₄ Cl ] [ NH ₄ OH ] =4.74+ 2 2 =4.74+ 1=4.74 pH =14-4.74=9.26 gathered