Molarity of 95% (w/w) formic acid (HCOOH)

Molarity of 95% (w/w) formic acid (HCOOH)

Overview:

  • Formic acid is supplied as clear colourless liquid. A 95% (w/w) concentrated formic acid can be obtained from different suppliers. (see suppliers)
  • 95% (w/w) formic acid means that 100 grams of Formic contains 95 grams of HCOOH.
  • The density of 95% (w/w) formic acid is 1.22 g/ml at 25°C that means that weight of the 1 ml of formic acid is 1.22 grams at 25°C.
  • Molarity refers to number of moles of the solute present in 1 litre of solution.
  • In simple words, 1 mole is equal to atomic weight of the substance. For example, 1 mole of formic acid is equal to 46.03 grams of HCOOH (molecular weight = 46.03).

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Calculation procedure:

Known values:
Density of Formic acid :                                1.22 g/ml
Molecular weight of HCOOH:                      46.03 g/mole

Concentration of Formic acid:                    95% (% by mass, wt/wt)

Step 1: Calculate the volume of 100 grams of formic acid.

Formula:
Density =  weight / volume    or

Volume =  weight / density

Volume of 100 gram of formic acid: 100/1.22 = 81.967 ml

Note: 95% (w/w) Formic acid means that 100 grams of solution contains 95 grams of HCOOH.

The volume of 100 grams of formic acid is 81.967 ml. That means 95 grams of HCOOH is present in 81.967 ml of  formic acid.

Step 2: Calculate how many grams of HCOOH is present in 1000 ml of Formic acid.

81.967 ml of Formic acid contains        =     95 grams of HCOOH
1 ml of Formic acid will contain           =     95/81.967 grams of HCOOH

1000 ml of Formic acid will contain    =     1000 x 95/81.967 =     1159.003 grams of HCOOH

1000 ml of formic acid will contain 1159.003 grams of HCOOH.

Step 3: Calculate the number of moles of HCOOH present in 1159.003 grams of HCOOH.

46.03 grams of HCOOH is equal to 1 mole.
1 gram of HCOOH will be equal to 1/46.03 moles.

444.01776 grams will be equal to = 1159.003 x 1/46.03 = 25.179 moles

Therefore, we can say that 1 litre of formic acid contains 25.179 moles of HCOOH or in other words molarity of 95% (w/w) Formic acid is equal to 25.179 M.