Determining Molar Mass in Titration

We wish to identify an unknown monoprotic acid. A 0.026 M solution of magnesium hydroxide is used in the titration. To begin, 0.018 grams of the unknown acid are dissolved in 200 mL of water prior to titration. Determine the molar mass of the unknown acid if the equivalence point (pH 7) is at the point when 22 mL of Magnesium Hydroxide (base) is added.