The ache or "burn" you feel in your muscle during strenuous exercise is caused by the accumulation of lactic acid. the hydrogen atom of the cooh group is acidic, and it can be removed using base to form a cooh- group. to determine the concentration of a solution of lactic acid, a chemist titrates a 24.25ml sample of it with 0.1010 m naoh, and it finds that 14.83m: of titrate is required to reach teh equivalent point.