Study Guides/Chemistry/Barium Sulphate Formula
Study Guide · Chemistry

What is the Formula of Barium Sulphate?

If you are studying 'Chemical Reactions and Equations' in CBSE Class 10 Chemistry, you will repeatedly encounter a highly famous double-displacement reaction that produces a thick, milky white solid.

That insoluble white solid is Barium Sulphate. The exact chemical formula for Barium Sulphate is BaSO₄.

Question (Click to Flip)

What is the chemical formula of Barium Sulphate?

Answer

The chemical formula of Barium Sulphate is BaSO₄.

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Key Facts

Chemical Formula: BaSO₄.

Molar Mass: 233.38 g/mol.

Physical Appearance: A heavy, thick, odorless white crystalline powder.

Solubility: Highly Insoluble in water (It sinks to the bottom).

Key Reaction Type: It is the ultimate classic example of a Double Displacement and Precipitation reaction.

How is the Formula Derived? (The Cross-over Method)

To build the formula, you must look at the valency (charge) of the two massive ions involved:

  1. The Barium Cation: Barium (Ba) belongs to Group 2 of the periodic table, so it loses 2 electrons. Its charge is Ba²⁺.
  2. The Sulphate Anion: Sulphate is a complex polyatomic ion made of sulfur and oxygen. Its strict permanent charge is SO₄²⁻.

Because the +2 positive charge of Barium perfectly cancels out the -2 negative charge of Sulphate, they lock together in a simple 1:1 ratio. Therefore, you do not write Ba₂(SO₄)₂; you simplify it to just BaSO₄.

The Famous White Precipitate Reaction

In board exams, this chemical is incredibly famous because it is completely insoluble in water. When you mix clear Barium Chloride liquid with clear Sodium Sulphate liquid, a massive chemical reaction instantly occurs, and thick, milk-like solid flakes of BaSO₄ instantly crash out of the liquid and fall to the bottom of the test tube. This is called a White Precipitate. Reaction: BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s)↓ + 2NaCl(aq)

Medical Use (The Barium Swallow)

Because Barium Sulphate is a heavy, dense metal compound that cannot dissolve in the human stomach, doctors use it brilliantly in medicine. If a patient has a stomach ulcer, the doctor makes them drink a thick, chalky milkshake of pure BaSO₄. Because the heavy Barium blocks X-Ray lasers, the doctor can take a perfect, glowing X-ray photograph of the inside of the patient's stomach.

Questions and Answers

What is the chemical formula of Barium Sulphate?+

The chemical formula of Barium Sulphate is BaSO₄.

Why is the formula BaSO4 and not Ba2(SO4)2?+

Because Barium has a charge of +2 and Sulphate has a charge of -2. Since the charges perfectly cancel each other out in a 1:1 ratio, the numbers are dropped to form the simple formula BaSO₄.

What color is the precipitate of Barium Sulphate?+

When formed in a chemical reaction, Barium Sulphate always drops out of the solution as a thick, milky White Precipitate.

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