Question

Enter your answer in the provided box. Calculate the pH at the equivalence point in the titration of 30.0 mL of 0.155 M methylamine (A= 4.4 x 10 ) with 0.280 MHCI. pH =

Answer 1

See the calculation of pH at equivalence point of the titration of weak base with strong acid is a bit difficult.

first you have to calculate the amount/ volume of strong acid(HCl here) is required for the neutralization. Then you have to calculate the K_a value for the conjugate acid that is produced due to neutralization. From there you will be able to calculate the H⁺ concentration and hence pH.

At equivalence point you have to consider the equilibrium between the conjugate acid formed from the base and water.

Please follow each step of the solution very carefully, I know its complicated.

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conceutecation of CtHa NHz= 7 .099 M ctt ilidaiungquiralante point kw 14 1.0 x10 mow 2.27 X/D 4.1X164 at ezuiblaieny Tequirale. Rlhe leuce peint (ag) CNH CtHz NH3 H parctially eliselaad ehe acid 0.699-X .CHNH Reucr 2.27 X10 a O.099-2 st Ctg NH3 acid e he Sinco is vesy les olissolued &0 Co.099 -) 0.099 X 2.27 X10 O.099 /2 2.2473 X1O CHt I49 x1O -equivalnes pair ng '. pH at s5.824