You prepare a solution from 10.0 mL of 0.100 M MOPS buffer (3-morpholinopropane-1-sulfonic acid) and 10.0 mL of 0.086 M NaOH. Next, you add 1.00 mL of 8.87 × 10-4 M lidocaine to this mixture Denoting lidocaine as L, calculate the fraction of lidocaine present in the form LH .

Question

You prepare a solution from 10.0 mL of 0.100 M MOPS buffer (3-morpholinopropane-1-sulfonic acid) and 10.0 mL of 0.086 M NaOH. Next, you add 1.00 mL of 8.87 × 10-4 M lidocaine to this mixture Denoting lidocaine as L, calculate the fraction of lidocaine present in the form LH .
ka= 6.3x10^-8
kb=8.7x10^-7

Devron · Answer

This is what I think, but I can not be sure.

0.001 moles of MOPS buffer
0.00086 moles of NaOH
1.4 x 10^-4 moles of MOPS left to react with L

1.4 x10^-4/total volume =6.67 x 10^-3 M of MOPS
8.87 x 10^-7 moles of L/total volume=4.2 x 10^-5 M for L

HA + L--> A + LH

8.7 x 10^-7=x^2/(6.67 x 10^-3 M)(4.22 x 10^-5 M)

x=4.95 x 10^-7

4.95 x 10^-7/4.2 x 10^-5 M =1.17x 10-2

Once again I am not sure!!!!!!