In: Chemistry
1.687 g of N-2-acetamido-2-aminoethane-sulfonic acid potassium salt (ACES–K , MW = 220.29 g/mol) is dissolved in 90.76 mL of water. 15.18 mL of HCl is added to the solution, resulting in a pH of 7.25. Calculate the concentration of the HCl solution. The pKa of ACES is 6.85.
no of moles of ACEs = W/G.M.Wt = 1.687/220.29 = 0.00765 moles
ACES + HCl --------------> HACES
I 0.00765 x 0
C -x -x +x
E 0.00765-x 0 +x
PH = PKa + log[HACES]/[ACES]
7.25 = 6.85 + logx/0.00765-x
7.25-6.85 = logx/0.00765-x
0.4 = logx/0.00765-x
logx/0.00765-x = 0.4
x/0.00765-x = 100.4
x/0.00765-x = 2.5118
x = 2.5118*(0.00765-x)
x = 0.01921-2.5118x
x+2.5118x = 0.01921
3.5118x = 0.01921
x = 0.01921/3.5118 = 0.0055moles
no of moles oc HCl = x = 0.0055moles
molarity of HCl = no of moles/volume in L
= 0.0055/0.01518 = 0.362 M >>>>>> answer