How Can We Prepare 0.1 N HCl Solution?

Hydrochloric acid (HCl) is a potent acid that is frequently employed in a variety of laboratory applications. If a solution is labelled as 0.1 N HCl, it signifies that each litre of the solution contains 0.1 moles of HCl. For the preparation of this solution, strong HCl and deionized or distilled water are required.

Prerequisites

Before preparing a 0.1 N hydrochloric acid (HCl) solution, a few prerequisites need to be considered. These prerequisites ensure the accuracy and safety of the preparation process. Here are the key prerequisites:

• Chemical Purity: To guarantee precise outcomes, it's critical to utilise high-quality chemicals. The preparation should be made with concentrated HCl that is known to be pure and of a known concentration. To ensure accurate measurements and trustworthy findings, analytical-grade chemicals should be used.
• Accurate Measuring Equipment: Accurate measuring tools are necessary to calculate the necessary volume of concentrated HCl and water. It is common to use a volumetric flask or a calibrated measuring cylinder for this. It is critical to make sure the measuring tools are spotless, dry, and free of any contamination that can compromise the precision of measurements.
• Safety Precautions: There are some risks while working with concentrated HCl. Following the proper safety procedures is so essential. If you want to guard against chemical splashes, put on personal protection equipment (PPE) including gloves, safety goggles, and a lab coat. To prevent breathing in the corrosive vapours, carry out the preparation in a place that is well-ventilated or inside of a fume hood.
• Dilution Technique: To avoid dangerous reactions, concentrated HCl must be diluted using a precise method. Never forget to add the acid to the water, never the other way around. Pour the concentrated HCl into the water slowly while stirring continually. By using this method, the risk of splashes and strong reactions that could happen if water is added to the concentrated acid is reduced.
• Water Quality: To avoid dangerous reactions, concentrated HCl must be diluted using a precise method. Never forget to add the acid to the water, never the other way around. Pour the concentrated HCl into the water slowly while stirring continually. By using this method, the risk of splashes and strong reactions that could happen if water is added to the concentrated acid is reduced.
• Calibration and Standardization (Optional): The prepared 0.1 N HCl solution should be calibrated and standardised if exact accuracy is desired. This can be achieved by titrating a suitable primary standard substance, such as sodium carbonate. If necessary, the concentration of the solution can be changed using the amount of HCl solution needed to neutralise the primary standard ingredient.

Principle

• The idea of normalcy (N) and the stoichiometry of the acid form the basis for creating a 0.1 N hydrochloric acid (HCl) solution. The number of gramme equivalents of solute per litre of solution is known as "normality," and it serves as a gauge for acid or basic solution concentration.
• Since HCl is a potent acid that totally dissociates in water, the concentration is frequently stated in terms of normalcy in this case. Chloride ions (Cl-) and hydrogen ions (H+) are created when HCl dissolves in water. The dissociation response looks like this:
• H+(aq)+Cl-(aq)= HCl(aq)
• The HCl solution's normalcy tells you how many moles there are in each litre of the solution. There are 0.1 moles of HCl in one liter of a solution of 0.1 N HCl. As a result, a litre of the solution will contain 36.46 grammes, or 0.1 moles, of HCl.
• Concentrated HCl is diluted with deionized or distilled water to create a solution of 0.1 N HCl. Accurately estimating the volume of concentrated HCl and adding it to a container with less water allows for effective dilution. More water is then added to the entire amount to bring it to the final volume that is wanted.

Standardization of 0.1N Hcl Solution

1.Preparation of the Standard Solution:

• An initial standard is necessary to standardise the 0.1 N HCl solution.
• Since it has a high degree of purity and stable chemical makeup, sodium carbonate (Na2CO3) is frequently employed as a main standard.
• Analytical balance a known quantity of anhydrous sodium carbonate (about 0.53 g) and transfer the weight to a fresh, dry beaker.

2.Dissolving Sodium Carbonate:

• The sodium carbonate in the beaker should be dissolved by adding a little amount of distilled water and swirling slowly with a glass stirring rod.
• Making sure sodium carbonate dissolves completely is crucial. If more distilled water is needed, it can be added.

3.Addition of Indicator:

• It is necessary to use a suitable indicator to determine when the reaction between sodium carbonate and hydrochloric acid has finished.
• In this situation, markers like phenolphthalein or methyl orange are frequently utilised.
• The chosen indicator should be added in small amounts to the sodium carbonate solution. The indication will make it easier to see the titration's conclusion.

4.Titration with Hydrochloric Acid:

• Make sure the burette is thoroughly cleaned and filled before adding the prepared 0.1 N HCl solution to it.
• The sodium carbonate solution beaker should be placed on a white tile or in good lighting for easy observation.
• Stirring continuously, gradually add the sodium carbonate solution to the 0.1 N HCl solution from the burette.
• The indicator will change colour when the sodium carbonate and hydrochloric acid interact. The reaction is almost finished when the colour changes, which means.

5.Endpoint Determination:

• Add drops of the hydrochloric acid solution at a time until a noticeable colour change is seen
• When the solution changes from yellow to orange, it has attained the endpoint for methyl orange.
• The endpoint for phenolphthalein is reached when the pink solution turns colourless.

6.Volume Calculation:

• Take note of the burette's first and final readings before and after the titration procedure. The amount of hydrochloric acid used to neutralise the sodium carbonate solution can be determined by comparing the two measurements.
• To ensure precise and reproducible results, perform repeated iterations of the titration procedure.
• Determine the typical hydrochloric acid usage volume for the titration.

Determination of Concentration:

• To determine the concentration of the hydrochloric acid solution, use the balanced chemical equation for the reaction between sodium carbonate and hydrochloric acid:
  Na2CO3 + 2HCl ? 2NaCl + H2O + CO2
• One mole of sodium carbonate interacts with two moles of hydrochloric acid, as shown by the equation. It is possible to figure out how many moles of hydrochloric acid were used in the titration because the molecular weight of sodium carbonate is known..
• To get the concentration of the 0.1 N HCl solution, divide the quantity of hydrochloric acid used by the number of moles of hydrochloric acid

Steps to Calculate

1. Concept of Normality (N):Chemical equivalents per litre (eq/L) is a unit of measurement used to describe a solution's concentration. Because one mole of acid creates one equivalent of hydrogen ions during a chemical reaction, normalcy for monoprotic acids like HCl is equal to the molarity (M). As a result, a 0.1 N HCl solution is the same as a 0.1 M HCl solution.

2. Molecular Weight of HCl: One hydrogen atom and one chlorine atom make up hydrochloric acid (HCl), which is abbreviated as HCl. One gramme per mole of hydrogen and 35.5 grams per mole of chlorine, respectively, make up their atomic masses. These atomic weights added together yield 36.5 g/mol as the molecular weight of HCl.

3. Calculation of Required Concentration:To calculate the amount of HCl needed to prepare a 0.1 N solution, the formula for normality is used: Normality (N) = (Weight of Solute in grams / Equivalent Weight in grams) / Volume of Solution in liters
In the above case, if we want to prepare a 0.1 N solution of HCl. The equivalent weight of HCl is equal to its molecular weight because it donates one equivalent of hydrogen ions in a chemical reaction. The desired volume of the solution should be specified.
For example, if we want to prepare 1 liter (L) of 0.1 N HCl solution: Normality (N) = 0.1 N Volume of Solution (V) = 1 L Equivalent Weight (EW) = Molecular Weight (MW) of HCl = 36.5 g/mol
Rearranging the formula, we can calculate the weight of HCl: Weight of HCl (in grams) = Normality (N) x Equivalent Weight (EW) x Volume of Solution (V) Weight of HCl = 0.1 N x 36.5 g/mol x 1 L Weight of HCl = 3.65 grams

Therefore, to prepare 1 L of 0.1 N HCl solution, you would need approximately 3.65 grams of hydrochloric acid.

4. Dilution with Solvent: After calculating the weight of HCl required, the next step is to dissolve it in a suitable solvent, typically distilled water, to achieve the desired volume of the solution. Graduated cylinders or volumetric flasks can be used to measure the volume accurately.

• For example, if you want to prepare a 500 mL (0.5 L) 0.1 N HCl solution:
• Dissolve 3.65 grams of HCl in a small volume of distilled water.
• Transfer the solution to a graduated cylinder or volumetric flask.
• Add distilled water to the desired final volume of 500 mL (0.5 L).
• Stir or shake the solution to ensure thorough mixing.

5. Verification: To ensure the accuracy of the prepared solution, it is recommended to verify its concentration using appropriate analytical techniques such as acid-base titration or pH measurement. This will confirm that the solution indeed has a normality of 0.1 N.