Why  primary alchohols are more acidic than secondary and tertiary

In case of alcohols acidic characters depends upon the O-H bond polarity. More the polar bond more acidic will be the respective alcohol. This polarity gets affected by electron donating group. If electron donating group increases polarity decreases.

 

The number of electron donating groups decreases in order:

Tertiary alcohol > Secondary alcohol > primary alcohol

Primary alcohols has more polar O-H bond than secondary alcohol and secondary alcohol has more polar O-H bond than tertiary alcohol.

 

Thus acidic strenght decreases in the following order:

Primary alcohol > secondary alcohol > tertiary alcohol