Question

To form a buffer whose pH is 7.00, how many moles of NaCN must be added to 1.0 L of 0.5 M HCN? Ka = 6.2 x 10–10 for HCN. Assume that the addition of NaCN does not change the volume of the solution.

Answer 1

pH is 7.00, 

how many moles of NaCN 

1.0 L of 0.5 M HCN? Ka = 6.2 x 10–10 for HCN.

1M = 49.0072 g/mol

0.5 = ( 0.5 )( 49.0072)

24.5035g

(6.2 x 10^-10)(24.5035)

= (1.5192 (10^-8))(1000)

= 0.000015192 moles