Methanol, a common laboratory solvent, poses a threat of blindness or death if c
ID: 622466 • Letter: M
Question
Methanol, a common laboratory solvent, poses a threat of blindness or death if consumed in sufficient amounts. Once in the body, the substance is oxidized to produce formaldehyde (embalming fluid) and eventually formic acid. Both of these substances are also toxic in varying levels. The equilibrium between methanol as the formaldehyde can be described as follows: CH3OH(aq)<=======> H2CO(aq)+H2(aq) Assuming the value of K=3.7*10^-10 what are the equilibrium concentrations of each species you start with a 1.24M solution of methanol? What will happen to the concentration of methanol as the formaldehyde is further converted to formic acid?Explanation / Answer
let the degree of dissociation be .so,
CH3OH(aq)<=======> H2CO(aq)+H2(aq)
initial 1.24 0 0
final 1.24(1-) 1.24 1.24
so k=[H2][H2CO]/[CH3OH]
or 3.7*10^-10= 1.24*1.24/1.24(1-)
or 3.7*10^-10= 1.24^2/(1-)
neglecting 1-,
3.7*10^-10= 1.24^2
or =1.727*10^-5
so [CH3OH]1.24 (since 1-1 (the value will be slightly less than 1.24))
[H2]=1.24
=2.142*10^-5
[H2CO]=1.24
=2.142*10^-5
the concentration of methanol will decrease to form more formaldehyde to maintian the equilibrium constant)