3.   Lactic acid, HC3H5O3, is the acid, which forms when milk sours. As its formula indicates, this acid has an acid hydrogen ion. It requires 22.4 mL of NaOH at 0.156 M to neutralize the acid in a sample of 25.0 mL of lactic acid. Calculate the mass of lactic acid contained in the sample.

4.   Vinegar is a dilute solution of acetic acid. What is the concentration of acetic acid in the vinegar if 26.5 mL of NaOH at 0.250 M are required to neutralize 10.0 mL of vinegar?                                                       

5.   ASA tablets contain the analgesic acetylsalicylic acid, HC9H7O4, which has an acid hydrogen ion. During titration of a tablet of 0.250 g of ASA, 38.5 mL of KOH at 0.0223 M were required to reach end point. What was the percentage by mass of the acetylsalicylic acid in the tablet?

I got through the first couple ok and now I just can’t get it. Please show each step so I will understand as I move to the exam