What mass of sodium cyanide must be added to 250 mL of water at 25 degrees Celsius in order to obtain a solution having a pH of 10.50? (Ka(HCN)= 4.9*10^-10)
Sat, 2009-09-19 23:32
Set up your ICE table for the reaction
CN- + H2O HCN + OH-
Use the pH to calculate [H+] at equilibrium.
Use [H+] to find [OH-]
Use ka given to find kb for cyanide.
solve fo [CN-]
use concentration and volume to solve for moles of cyanide then convert to mass of NaCN.
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