Experiment 98

Objective

To prepare a 250 mL standard solution of 0.1 M hydrochloric acid (HCl) using a concentrated 12 M HCl solution.

Introduction

Hydrochloric acid is a primary standard liquid substance, allowing for preparation of a standard solution by diluting a known concentration of HCl. In this experiment, we will use a 12 M concentrated HCl solution to prepare 250 mL of a 0.1 M HCl solution.

Dilution Formula Used:

V1 × S1 = V2 × S2

Where:

●       V1 = Volume of the dilute acid = 250 mL

●       S1​ = Strength of the dilute acid = 0.1 M

●       V​2 = Volume of the concentrated acid (to be determined)

●       S2​ = Strength of the concentrated acid = 12 M

Calculation:

V2 = 250 x 0.1 / 12 = 2.08 mL of concentrated HCl

Thus, adding 2.08 mL of 12 M concentrated HCl to 250 mL of distilled water will produce a 0.1 M HCl solution.

Materials

Chemicals

●      12 M Concentrated HCl

●      Distilled water

Apparatus

●      250 mL volumetric flask

●      Funnel

●      10 mL pipette

●      Balance (if required for other measurements)

Procedure

1.    Preparation of the Flask

●      Wash the 250 mL flask thoroughly with distilled water.

●      Dry the flask in an oven to remove any residual moisture.

2.    Preparation of the Solution

●      Use a pipette to measure precisely 2.08 mL of the 12 M concentrated HCl.

●      Add this 2.08 mL of concentrated HCl to the 250 mL flask using a funnel.

●      Carefully add distilled water to the flask until the total volume reaches 250 mL.

●      Mix the solution thoroughly to ensure uniform concentration.

Observation

Adding 2.08 mL of 12 M HCl to distilled water in a 250 mL flask produces a solution with a concentration of 0.1 M.

Questions

1.    What is a primary standard substance?

2.    What is a primary standard solution?

3.    What is a 0.1 M HCl solution?

4.    What is the molecular weight of HCl?

5.    Define solute.

6.    Define solvent.

7.    Define solution.