How to Calculate Titration Value

Standardization of a Hydrochloric Acid Solution by Titration of a Known Mass of Reactant

• 1

  Suppose a chemistry problem requires you to "standardize" a hydrochloric acid (HCL) solution that has an approximate molarity (M) of 0.1.

  Note that molarity is defined as the molar mass of a chemical substance per liter of solution.

  Assume that the HCL solution was standardized by titration of 0.275 grams (g) of pure sodium carbonate, Na2CO3, to an end-point indicated at 48.5 milliliters (ml) of HCL.

• 2

  Write the chemical equation of the reaction: Na2CO3 + 2HCL = 2NaCL + H2O + CO2.

  Note that the molar ratio of the reaction is 2 moles of HCL / 1 mole of Na2CO3.

• 3

  Calculate moles of Na2CO3 by dividing the mass of NaCO3 by its molar mass, as follows: 0.275 g NaCO3 / [106.0 g Na2CO3 / 1 mole Na2CO3] = 0.00259 moles Na2CO3.

• 4

  Multiply moles of Na2CO3 by the molar ratio to find moles of HCL, as follows: 0.00259 moles Na2CO3 x [2 moles HCL / 1 mole Na2CO3] = 0.00518 moles HCL.

• 5

  Calculate the concentration value, or molarity, of the HCL solution, as follows: 0.00518 moles HCL / [48.5 ml HCL x 1 liter / 1000 ml] = 0.107 M.

Standardization of a Barium Hydroxide Solution by Titration with Standardized Hydrochloric Acid

• 6

  Suppose that the HCL solution in section 1 is used to standardize a solution of barium hydroxide, Ba(OH)2.

  Assume that 37.6 ml of Ba(OH)2 is titrated to an end-point indicated at 43.8 ml of HCL.

• 7

  Write the chemical equation of the reaction: Ba(OH)2 + 2HCL = BaCL2 + 2H2O.

  Note that the molar ratio of the reaction is 1 mole Ba(OH)2 / 2 moles HCL.

• 8

  Calculate moles of HCL, as follows: 0.107 moles HCL / liter x 43.8 ml HCL x 1 liter / 1000 ml = 0.00469 moles HCL.

• 9

  Calculate moles of Ba(OH)2, as follows: 0.00469 moles HCL x [1 mole Ba(OH)2 / 2 moles HCL] = 0.00235 moles Ba(OH)2.

• 10

  Calculate the molarity of the Ba(OH)2 solution, as follows: 0.00235 moles Ba(OH)2 / [37.6 ml Ba(OH)2 x 1 liter / 1000 ml] = 0.0625 M.