Hydrogen Chloride Solubility: 7 Facts (With Infographic Img)

HCl is highly soluble in water. At 25°C, 720 g/L of HCl dissolves, forming a 37-38% solution (11.6 M). Dissolution is driven by HCl’s polarity (dipole moment: 1.08 D) and dissociation into H+ and Cl- ions (pKa = -7.0). Solubility decreases with temperature (823 g/L at 0°C, 520 g/L at 60°C) and increases with pressure (1,200 g/L at 10 atm).

Can Hydrogen Chloride Dissolve in Water

How Does the Polarity of HCl Influence Its Solubility in Water?

The polarity of the hydrogen chloride (HCl) molecule plays a crucial role in its solubility in water. The electronegativity difference between the hydrogen and chlorine atoms is 0.96, resulting in a dipole moment of 1.08 D. This high polarity allows HCl to interact strongly with the polar water molecules through hydrogen bonding.

AtomElectronegativity
Hydrogen2.20
Chlorine3.16

To experimentally demonstrate the polarity of HCl and its effect on solubility:

  1. Set up a gas generator with concentrated sulfuric acid (H2SO4) and sodium chloride (NaCl) to produce HCl gas.
  2. Bubble the HCl gas through a series of polar and non-polar solvents, such as water, ethanol, and hexane.
  3. Observe the solubility of HCl in each solvent by measuring the pH change or the conductivity of the resulting solution.

The HCl gas will readily dissolve in polar solvents like water and ethanol, while showing limited solubility in non-polar solvents like hexane.

What Is the Dissociation Process of HCl in Water?

When HCl gas is introduced into water, it dissociates almost completely into H+ and Cl- ions:

HCl (g) + H2O (l) -> H3O+ (aq) + Cl- (aq)

The H+ ion combines with water to form the hydronium ion (H3O+), while the Cl- ion remains solvated in the aqueous solution.

IonHydration Enthalpy (kJ/mol)
H+-1,091
Cl--363

To demonstrate the dissociation process:

  1. Prepare a 1 M HCl solution by diluting concentrated HCl with deionized water.
  2. Measure the pH of the solution using a calibrated pH meter. The pH should be around 0, indicating a high concentration of H+ ions.
  3. Conduct a conductivity test using a conductivity meter. The high conductivity (e.g., 332 mS/cm for 1 M HCl at 25°C) confirms the presence of mobile H+ and Cl- ions.

How Does the Concentration of HCl Affect Its Solubility?

The solubility of HCl in water is extremely high, with a saturated solution containing approximately 37-38% HCl by mass at room temperature. This corresponds to a molarity of 11.6 M.

ConcentrationMolarity (M)Mass Percentage
Concentrated HCl11.637-38%
1 M HCl1.03.6%
0.1 M HCl0.10.36%

To prepare HCl solutions of varying concentrations:

  1. Use a volumetric flask and pipette to accurately measure and transfer concentrated HCl and deionized water.
  2. For a 1 M HCl solution, pipette 83 mL of concentrated HCl (37% by mass) into a 1 L volumetric flask and dilute to the mark with deionized water.
  3. For a 0.1 M HCl solution, pipette 10 mL of the 1 M HCl solution into a 100 mL volumetric flask and dilute to the mark with deionized water.

Always handle concentrated HCl with caution, using proper personal protective equipment (PPE) such as gloves, lab coat, and safety goggles.

What Factors Influence the Solubility of HCl in Water?

Several factors can influence the solubility of HCl in water:

  1. Temperature: The solubility of HCl decreases with increasing temperature. At 0°C, the solubility is 823 g/L, while at 60°C, it decreases to 520 g/L.
  2. Pressure: Higher pressure increases the solubility of HCl in water. At 10 atm, the solubility increases to 1,200 g/L.
  3. Ionic strength: The presence of other ions in the solution can affect the solubility of HCl through the common ion effect and the formation of ion pairs.

To investigate the effect of temperature on HCl solubility:

  1. Prepare a saturated HCl solution at room temperature by bubbling HCl gas through water until no more gas dissolves.
  2. Measure the concentration of the saturated solution using a titration method, such as titrating against standardized NaOH.
  3. Repeat the experiment at different temperatures (e.g., 0°C, 20°C, 40°C, and 60°C) by using a temperature-controlled water bath.
  4. Plot the solubility of HCl (in g/L) against temperature to observe the trend.

There are potential differences between Dissolution and Solubility. You can understand the same here.

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