which is more basic, OH- or CH3O-?
I thought it would be OH- because when one looks at the conjugate acids of these two ions, methanol is slightly more acidic which implies that it is slightly less basic and the hydroxide ion is the more basic. But apparently this is not the case so could you please clarify.
commented below.
To determine which of the two ions, OH- (hydroxide) or CH3O- (methoxide), is more basic, we can compare their respective conjugate acids. The stronger the acid, the weaker the base.
In this case, the conjugate acid of OH- is H2O (water), and the conjugate acid of CH3O- is CH3OH (methanol).
First, let's compare the acidity of water and methanol. Methanol (CH3OH) is a slightly stronger acid than water (H2O) due to the electron-donating methyl group (CH3) attached to the oxygen atom. This methyl group increases the electron density on the oxygen atom, making it more willing to donate a proton and making methanol a slightly more acidic molecule than water.
Now, when we compare the two conjugate acids, H2O and CH3OH, we find that H2O is actually a stronger acid than CH3OH. In other words, the conjugate base OH- is weaker (less basic) than the conjugate base CH3O-.
Therefore, based on the relative strengths of their conjugate acids, CH3O- is more basic than OH-.
To summarize:
- OH- is the conjugate base of water (H2O).
- CH3O- is the conjugate base of methanol (CH3OH).
- Methanol (CH3OH) is a slightly stronger acid than water (H2O) due to the presence of the methyl group.
- The stronger the acid, the weaker the conjugate base. Therefore, CH3O- is more basic than OH-.
Remember, the concept of acidity and basicity is determined by the strength of the conjugate acids, and in this case, the presence of the methyl group in methanol makes it slightly more acidic than water, leading to CH3O- being the more basic ion.