Question

1.Calculate the pH at the following points in the titration of 50.0 mL of 0.100 methylamine (CH,NH), Kb = 4.4 x 104, with a 0.200 M HCl solution before any acid is added, after adding 0.0mL, 15.0 mL, 25.0 mL, 35.0 mL and 50 mL of HCl. Plot (using graph paper) the titraticn curve from your results (label all relevant points).

Answer 1

iUtn Volume 50mL = 0.050し moles of LoH1 (6.6 xlo3M)x Voume) ร์เ . 6 x 10-3) x 0.050 = 0.33x )03 = 3.3 χ ,δ"moles O Befonc additi of add., 6.6XIO ρί0H): 2.18

2 150 mL of Hu oddd Molavity of Hu200 AM moles of HUL = 0.200 md/L x 0.015 L Hem, moles of H 003 moles Also, moles of он.-331 юч-D. 00033 Yndes H+ + OH--> H20 Htmcuninç m solutiom 0-003 O.oo033 0.00267 Yndes Tota volume= 50 m Lt l5mL 65mL ご0.065L Hon«, LHt] 0.00267 moles /0,065 L 0,041 Ynd/L 3 25-0 mL of Hd added moles of Hu0200olL x 0 025L 0.005 moles Hene, simi lan to paxt,

moles of H nin 005.oo033 4 35.0 m of Hl added '< e mlu, 1 td 0,00 7-1).OOL, 33 こ [n'] : 0.00861/10-OSO+0.035 ) :: 0.0066.1 /0.085ご0.0185ト o 185) 5) 50-0 mL of Hu added O 009 67 molcs [h']ニ0.00967 moles/ (0.050 to-o50) -0.0961ト!

13 2 3 2 O 5 o 15 20 25 30 35 40 45 50 55 60 65 10

I hope it helps. For further clarification please ask in comments.