Question

I know that the answers are: 1)ph=10.88, 2a) 10.71, 5.08, 0.79 but I'm having problems with figuring out the work for question two

Thank you

A buffer solution is prepared by taking 72.3 g CH3NH3Cl and 315 mL of 5.85 MCH3NH2 and diluting to a final volume of 500.0 mL. Determine the pH of the buffer solution. zeexagPH1O .88 2) 50.0 ml of the buffer prepared in problem 1 above is titrated with 3.86 M HCI. a) Determine the pH of the solution resulting solution after each amount of HCl is added. (Volumes of HCI given below represent the total amount of HCI added at that point in the titration.) i) After 7.32 mL is added. before ea.P O. i) After 47.80 mL is added. e ea P 5.08) iii) After 52.05 mL is added, after eq, P+ (o?n ) b) Sketch a smooth titration curve on graph paper using the data points determined on this worksheet. Although you will have only four data points, you should use your knowledge of how a titration curve should look for a complete titration to sketch this curve. Properly label and title your graph.

Answer 1

Given a buffer solution is prepared by taking 72.3gCH_3NH_3cl and 315ml of 5.85M CH_3NH_2 and diluting to a final volume of 500.0ml initial [CH_3NH_3^+] = 72.3g/65.518g/mol times 0.315L = 3.50m initial [CH_3NH_2] = 5.85m diluted to 500ml final [CH_3NH_3^3] = 3.50m times 0.315L/0.5L = 2.20M final [CH_3NH_2^+] = 5.85m times 0.315L/0.5L = 3.68 M PH of solution PH = pk_a + log (base)/(acid) 10.64 + log (3.68)/2.20) 10.86 50.0 ml of the buffer prepared in problem 1 above is titrated with 3.86 M Hcl titration with 3.86 M Hvl 7.32 ml added final [CH_3NH_3^+] = (2.20 times 500 + 3.86 times 7.32)/(507.32 = 2.22M final [CH_3NH_2] = (3.68 times 500 -3.86 times 7.32)/507.32 = 3.57M PH = PK_a + log(base)/(acid) 10.64 + LOG (3.57)/2.22) 10.84 47.80 ml added final [CH_3NH_2] = (3.68 times 500 -3.86 times 52.05)/(552.05) = 2.97 M PH = P_ka + log (base)/(acid) 10.64 + log (2.97)/(2.36) 10.74 sketch a smooth titration curve on graph paper using the data points determined on this worksheet