Effect of Pressure on Solubility-Henry’s Law

The effect of pressure on the solubility of a gas in a particular liquid at constant temperature can be readily understood in terms of Henry’s law which states that,

“At constant temperature, the mass of a gas dissolved in a unit volume of a liquid is directly proportional to the pressure of the gas above the liquid at equilibrium.”

Mathematically,   m ∝ p

         Or, m = k p

Where, m is the mass of the gas dissolved by unit volume of solvent,

              P is the pressure of the gas in equilibrium with the solution

              K is a proportionality constant known as Henry’s Law constant.

Applicability of Henry’s Law

For the strict applicability of Henry’s Law:

1. Temperature should be high
2. Pressure should be low
3. No chemical reaction should take place between the dissolved gas and the solvent (such as compound formation or association)

Electrolyte

Electrolyte

Electrolytes are also called “Electrolytic Conductors”.

“Electrolytes are electrovalent substances that form ions in solution which conduct an electric current.”
In other words, 
“An electrolyte is any substance containing free ions that make the substance electrically conductive.”

or

“Electrolytes are any substance that dissociates into ions when dissolved in a suitable medium or melted and thus forms a conductor of electricity.”

The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible. The most familiar electrolytes are acids, bases, and salts, which ionize when dissolved in such solvents as water or alcohol. Many salts, such as sodium chloride, behave as electrolytes when melted in the absence of any solvent; and some, such as silver iodide, are electrolytes even in the solid state.

Example:

Sodium Chloride, Copper Sulphate, Potassium Nitrate
Electrolytes are of two kinds:

1. Strong Electrolyte
2. Weak Electrolyte

Strong Electrolyte

A strong electrolyte is a solute that completely, or almost completely, ionizes or dissociates in a solution.
The solution will contain only ions and no molecules of the electrolyte. Strong electrolytes are good conductors of electricity.

Examples of Strong Electrolytes

Strong Acid

• Perchloric acid(HClO₄)
• Hydriodic acid (HI)
• Hydrobromic acid (HBr)
• Hydrochloric acid (HCl)
• Sulfuric acid (H₂SO₄)
• Nitric acid (HNO₃)
• Chloric acid (HClO₃)
• Bromic acid (HBrO₃)

Strong Base

• Potassium hydroxide (KOH)
• Barium hydroxide [Ba(OH)₂]
• Caesium hydroxide (CsOH)
• Sodium hydroxide (NaOH)
• Strontium hydroxide [Sr(OH)₂]
• Calcium hydroxide [Ca(OH)₂]
• Rubidium hydroxide (RbOH)
• Magnesium hydroxide [Mg(OH)₂]

Salts

• Sodium chloride
• Potassium nitrate
• Magnesium chloride
• Sodium acetate

Weak Electrolyte

A weak electrolyte is an electrolyte that does not completely dissociate in solution, rather undergoes partial ionization or dissociation.
The solution will contain both ions and molecules of the electrolyte. Here, in solution the ions and the dissociated molecules will be in equilibrium with each other. When such a solution is diluted, the degree of ionization increases. It becomes complete at infinite dilution.

Examples:

HCOOH, CH₃COOH, NH₄OH, CH₃NH₂, CH₃COONH₄, H₃PO₄ etc.