Question

What relative masses of dimethyl amine and dimethyl ammonium chloride do you need to prepare a buffer solution of pHpHpH = 10.04?

Answer 1

^{​​​​​​}henderson hasselbalch equation

p^{​​​​​OH =}p^{​​​​​​ kb} + log{[salt] _N/ [ base] _{N }}

_{if N=M then the equation becomes}

_{P ^OH = p ^kb + log{ n​​​​​​ salt / n base} where n= number of moles}

_{Here p ^kb of dimethyl amine is 3.27}

_{given p ^H = 10.4 then p ^OH = 3.6}

_{From above equation 3.6= 3.27 + log{ n salt/n base}}

_{Log{ n salt/n base} = 0.33}

_{n salt/ n base = 2.13 where n= weight/ gmw}

_{Wt base / Wt salt = 45/ 362.8*2.33 = 0.05}

_{( gmw of salt= 362.8) ( gmw of base = 45)}

Therefore the relative masses of dimethyl amine to dimethyl ammonium chloride is 0.05...