# Henry Law Formula

**What is Henry’s law?**

Henry’s law defines that at constant temperature, the concentration of the gas that is dissolved in a given liquid is proportional to the partial pressure of the gas above the fluid.

The Henry’s law constant is the expression for equilibrium distribution of a compound between water and gaseous phase denoted by KH. It indicates the volatility of the compound.

The mathematical expression for Henry’s law is given by

Where,

C is the solubility of the gas at a fixed temperature in a solvent (units in M or ml gas/L).

is the Henry’s law constant (units in M/atm)

is the partial pressure of the gas (units in Atm)

**Example 1**

Determine the quantity of carbon dioxide dissolved in a 1L bottle of carbonated water if the pressure of 2.4 atm is applied in the bottling process at 25 Degree Celsius? Given that of in water is 29.76 atm/(mol/L) at 25 Degree Celsius.

**Solution**

We know the equation

P=

Therefore,

C = P/KH

= 2.4 /29.76

= 0.08 mol/L of CO2

To convert into grams,

1 mole of CO2

= 12 + (16 x 2) = 44g

Mass of CO2 in grams = mol of CO2 x 44 g/mol

= 8.06 x 10-2 x 44

= 3.52 g of CO2 is dissolved in 1 L of carbonated water.

**Example 2**

Determine the solubility of carbon dioxide in water at 0oC and pressure of 3.0 atm. Given that Carbon dioxide solubility is 0.348 g/100 mL.

**Solution**

We know that solubility of carbon dioxide gas is directly proportional to the pressure of the gas over the liquid.

We have the equation

P =

Therefore,

Solubility = 0.348g /100 mL x 3 atm/1 atm

= 1.044 g/100 mL of water.

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