# OVERVIEW

A 95% (w/w) Formic acid can be purchased from several commercial suppliers. It is a clear colorless liquid and can be diluted to prepare solutions of known concentrations. Here we describe a procedure to prepare a 1 M Formic acid solution using commercially supplied 95% stock solution.

# REQUIREMENTS

Reagents and solutions
95% (w/w) Formic acid solution
Distilled water

Equipment and disposables
Beaker (1 Liter)
Magnetic stirrer

OBJECTIVE
Preparation of 1 Liter of 1M Formic acid using concentrated stock solution (95%, w/w)

# PROCEDURE

Use personal protective equipment (lab coat, gloves, goggles etc) for your safety and follow the guidelines of your institute.

PART I: Calculate how much 95% (w/w) concentrated stock Solution is required to prepare 1 L of 1M Formic acid solution

Step 1: Calculate the molarity of 95% (w/w) concentrated Formic acid solution
The procedure to calculate molarity of 95% (w/w) concentrated Formic acid solution is described in detail in the post “Molarity of 95% (w/w) formic acid (HCOOH)”. From this post, you will know that the molarity of 95% (w/w) concentrated Formic acid solution is 25.17 M.

Step 2: Calculate how much concentrated stock solution is required to prepare 1L of 1M Formic acid solution using dilution method.

Dilution method is described in detail in the post “Preparing Working Solution from Stock Solution by Dilution”.

Use the following formula to calculate the volume of concentrated solution required for the preparation of 1 liter of 1M solution of hydrochloric acid solution

Formula:   Cf x Vf = CS x VS

Cf (concentration of diluted (final) solution) = 1M
Vf (volume of diluted (final) solution) = 1 liter
CS (concentration of stock solution) = 25.17 M
VS (volume of stock solution) = ? (unknown)

Place all values in the formula:

1 x 1 = 25.17 x VS

VS = 1 x 1/ 25.17 = 0.0397 liter (39.7 ml)

So you need 0.0397 liter (39.7 ml) of 95% (w/w) concentrated Formic acid solution to prepare a 1 liter of 1M Formic acid solution.

Step 3: Calculate the volume of solvent to be taken.

Final volume of diluted solution = 1Liter
Volume of concentrated solution = 0.0397 liter
Volume of solvent (water) required = 1 – 0.0397 = 0.9603 Liter

So you need to mix 0.0397 liter (39.7 ml) of concentrated solution to 0.9603 liter (960.3 ml) water to prepare 1 liter of 1 M Formic acid solution.

## PART II: Solution preparation

Step 4: Transfer 960.3 ml water in a beaker/volumetric flask/measuring cylinder. Add 39.7 ml of 95% Formic acid stock solution and mix it to prepare a homogeneous solution.
Note: In case you have not calculated the amount of water to be added, just take ≈ 500 ml water in a volumetric flask/measuring cylinder (capacity 1L) and add 39.7 ml of  95% Formic acid stock solution. Now adjust the final volume to 1 liter with water. Mix it.

STORAGE
Solution can be stored at room temperature.