IMAT 2018 Q49 (Chemistry)

Could someone help me with this question? Acids and bases are a weak spot of mine so I appreciate any info!

Consider this ionic equation in aqueous solution:

CH3O- + H2O → CH3OH + OH-

Which statement about this reaction is correct?

A Water is acting as a Bronsted-Lowry base.
B The CH3O- ion is a Lewis acid.
C The final mixture of solutions would have a pH below 7.
D CH3OH is the conjugate acid of CH3O-.
E The hydroxide ion is the conjugate acid of the water.

D is the answer. I’ll explain the options

A - wrong because water is donating an H+ which means it’s a Bronsted-Lowry acid
B - wrong because CH3O- is accepting an H+ which is a property of a base
C - wrong because there are hydroxide ions in the products which means the solution is above 7 - alkaline
D - correct because CH3O- is a base and when it accept the electron it becomes the conjugate acid
E- OH- is actually the conjugate base in this as H2O gave out the H+ (acts as an acid)

Hope this helped! Just know acids donate an H+ and becomes its conjugate base in the products while bases accepts the H+ and becomes its conjugate acid in the products.


Thank you so much this was really really helpful! I only have one question. Why is the pH of the mixture above 7 even though CH3OH is acidic and present in the same amount according to the mole ratio? I expected the pH to be neutral.

It is a weak acid and mixed with a strong base - the OH- ions so the solution is more basic than acidic! If they were both strong acid and strong base then it would be neutral as they are cancelled out :))


I see, it always goes back to the strong acids and bases. Thank you!!!

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