Barium sulfate (BaSO4) is insoluble in water since ofwater dipole toughness is also weak come pull far the anions and also cations that theBaSO4 together both Ba 2+ and SO4 2- ion are big and bigger cation stabilizes biggeranion strongly outcomes in BaSO4 has greater lattice energy.

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Why is BaSO4 insoluble in water?


For any kind of compounds to be dissolve or insoluble in water,lattice enthalpy and hydration enthalpy are two major aspects. First, we have toknow what lattice and hydration enthalpy are,
Lattice Enthalpy (Lattice Energy)

In basic terms, Lattice enthalpy is the power required tosplit a compound into its constituent ions i.e. Anions and also cations. In otherwords, it is a cohesive pressure that needs to bind ions of the compounds either in a gaseous state or in a solid-state and these space normally called formationand dissolution lattice power respectively.

Hydration Enthalpy (Hydration Energy)

Hydration enthalpy is simply defined as the lot of energyreleased as soon as one mole of ion combines v a water molecule. In a givenreaction, the has always a an adverse value together the power is released throughout theprocess which is additionally known as an exothermic reaction.


Higher the lattice energy, the molecule will certainly be much less soluble orhave less solubility. And the turning back of it, greater the hydration energy, the moleculewill be much more soluble or have greater solubility.

Now in the instance of BaSO4, the has greater lattice energybecause both Ba 2+ and SO4 2- ions are big and we know bigger cationsstabilize bigger anions much more strongly. Once it is liquified in water, that hydrationenergy decreases an ext rapidly than lattice energy.

For any kind of compound come be soluble in water, its latticeenthalpy should be lower and it must decrease more rapidly than hydrationenergy. However this process is reversed as soon as BaSO4 is put in water and also it isinsoluble.

Note: BaSO4 is not totally insoluble,it is sparingly soluble in water, and itsseparated ions are conveniently saturated v the undissolved precipitatedmolecule. Generally, most of the insoluble compounds are sparingly soluble asoutermost ions are separated quickly yet in very fewer quantities which arenegligible.

How is BaSO4 insoluble in Water?

As discussed earlier, hydration power when the water the molecule binds v ions room not so much stronger which is able come separatethe ions i.e. Cations and also anions of the BaSO4 molecule, together a result, BaSO4 isinsoluble in water.

We can also identify even if it is BaSO4 is soluble or insolublein water follow to the solubility rules i m sorry states most of the sulfatesare dissolve in water with exemption of Ba 2+, Ca 2+, Pb 2+, Ag 2+, and also Sr 2+.

Moreover, both solubility and solubility commodities of BaSO4are 0.0002448 g/100 mL (20°C) and also 1.0842×10-10 (25°C) which space extremelylower values when compared with soluble compounds prefer NaCl or HCl.

BaSO4 soluble or insoluble (Determining factors)

For any compound to be dissolve or insoluble in water, over there are plenty of factors that affected the solubility that the compounds. Below are some of the significant determining components which are responsible because that the solubility the BaSO4:
Solubility and also Solubility Product

Higher the solubility and also solubility product the themolecule, more soluble in water. But BaSO4 has very lower solubility (0.0002448g/100 mL) and also solubility product (1.0842×10-10) which provides it insoluble inwater.

Solubility Principle

According come the solubility principle “like dissolves like”which means similar type of solute is soluble in similar kind solvent i.e.polar molecules space most regularly soluble in polar solvents and also nonpolar room solublein nonpolar solvents.


Temperature has actually a very large role in the solubility the thecompounds. As soon as the temperature that the systems increases, solubility alsoincreases and vice-versa. In ~ room temperature BaSO4 is almost insoluble yet whentemperature increases, its ions begin separating more, and more andsolubility increases.

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pH value

pH has actually reciprocal relation with the sparingly dissolve basesor straightforward salts solubility i.e. When pH increases, solubility decreases and whilepH decreases, solubility increases.