25g of vinegar (a solution containing acetic acid) was addedto
a flask containing an indicator. 37ml of .46m koh solution wasadded
to the system from a burette to reach the equivalence point. what is
the percentage by mass of vinegar that is aceticacid?

Vinegar has 4.09% of acetic acid.

Explanation:

The neutralization reaction is:

Each mol of KOH reacts with each mole of acetic acid so the quantity of moles of acetic acid is:

The mass of acetic acid is:

0.01702 mol×60.02g/mol=1.0215 g Acetic Acid

Finally, the percentage is:

%=1.0215 g Acetic Acid÷25g vinegar(solution)=4.09%

it means there are 3 atoms of oxygen