Calculating Concentrations in a Buffer Solution

[adhlpi]

Homework Statement [/b]
A buffer solution was made using 50mL of 0.05M of ethanoic acid and 50mL 0.05 of sodium ethanoate. The question asks what is the concentration of ethanoic acid and ethanoate ions in the buffer solution. I assumed it would be 0.05M but when I asked for help I was told to work out the ethanaote ions by using Henderson-Hasselbalch equation first then work out the acid concentration. The pKa value of ethanoic acid is 4.76. I guess its something to do with the fact pH=pKa maybe, then find out the [H+]? so 10*-4.76 as my concentration

 

[Borek]

No need for HH equation here, but once you mix 50 mL with 50 mL final concentrations are not 0.05M. Think simple dilution.