Question

A 0.2597−g sample of a monoprotic acid neutralizes 177.7 mL of a 0.07307 M KOH solution. Calculate the molar mass of the acid.

Answer 1

Let us assume reaction between monoprotic acid (HA) and KOH as (I hope also its not weak acid, otherwise we cannot do calculation with given information, we need Ka value atlease in that case)

HA + KOH --> KA + H2O

1 mol acid neutralizes 1 mol base.

moles present in KOH = 177.7 mL x 10^-3 L x 0.07307 = 0.01298 mol

this means 0.01298 mol KOH exactly neutralizes 0.01298 mol of acid.

we know that moles = mass of substance / molar mass of substance

==> molar mass of substance = mass of substance / moles = 0.2597 g / 0.01298 mol = 20.0077 g/mol

the molar mass of the acid = 20.0077 g/mol

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