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Chemistry

Lactic acid, a chemical responsible for muscle fatigue, is a monoprotic acid. When 0.578 g of lactic acid is titrated with 0.206 M NaOH, a volume of 31.11 mL of NaOH is used. What is the molar mass of lactic acid?

HA + NaOH > NaA + H2O

(also does the A represent acid?)

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  1. Yes, the problem says lactic acid is a monoprotic acid so we write H for the acid part and A for the rest of the large molecule. It makes typing easier. The molar mass of lactic acid is 90.08.
    mols HA = grams/molar mas = 0.578/90.08 = approx 0.006 but you should use a more accurate number.
    mols NaOH = M x L = approx 0.006
    Look at the equation and you can see that 1 mol HA = 1 mol NaOH; therefore, mols HA must be approx mols NaOH or 0.007.
    Then M HA = mols HA/L HA.

    Post your work if you get stuck.

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  2. 12

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