Barium sulfate contains barium ions, Ba²⁺ sulfate ions, SO₄²⁻ (i) Give the formula of barium sulfate - Edexcel - GCSE Chemistry - Question 5 - 2013 - Paper 1

An ion is defined as a charged particle. It can be an atom or molecule that has gained or lost one or more electrons, resulting in a positive or negative charge.

Barium sulfate is considered safe for use in medical imaging because it is insoluble in water. This means that it does not dissolve in bodily fluids, allowing it to pass through the digestive system without being absorbed into the bloodstream. Therefore, it remains largely unchanged and does not present a risk to the patient's health.

To prepare a pure sample of barium sulfate, follow these steps:

1. Reactants: Measure specific amounts of barium chloride (BaCl₂) and sodium sulfate (Na₂SO₄) and mix them in a beaker with water to form a solution.
2. Mix Solutions: Stir the mixture thoroughly to ensure the reactants fully interact.
3. Precipitation: Barium sulfate will form as a precipitate during the reaction.
4. Filtration: Use a filter funnel and paper to separate the solid barium sulfate from the liquid mixture.
5. Washing: Wash the solid on the filter paper with distilled water to remove any impurities.
6. Drying: Allow the washed barium sulfate to dry completely in a warm place or leave it to air dry completely.

The balanced chemical equation for the reaction of barium and chlorine is:

$\text{Ba} + \text{Cl}_2 \rightarrow \text{BaCl}_2$

This indicates that one barium atom reacts with one molecule of chlorine gas to produce one formula unit of barium chloride.