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BARIUM SULFATE USED IN X-RAYS

Wanna see it?

Why barium?

It is a radiopaque or contrasting agent.

Chemical Systems & Equilibrium

Type of medical imaging that is used to examine the gastrointestinal tract through the ingestion of barium sulfate.

a substance used to improve the ability to see organs through an x-ray

Characteristics of barium sulfate

What is a barium x-ray?

substance that appears opaque to x-rays

Barium is a dry, white chalky metallic powder and is then mixed to create a thick, milkshake-like drink called the suspension.

Barium sulfate is ideal because:

1) has the ability to absorb x-rays

2) has low solubility

Barium sulfate can be taken in two different procedures:

barium swallow

given by an enema

examines areas such as the pharynx and esophagus

examines areas such as the colon or lower gastrointestinal tract

Because of this, by ingesting barium sulfate and coating the inner lining of your organs, you are able to see them through an x-ray. Barium is also an x-ray absorber.

Making Connections - SCH 4U0 - Mr. Brady - Michelle Truong

How does this relate back to our chemistry class?

Chemical equation for the dissolution of barium sulfate in water is:

How is this application connected to chemistry?

The low solubility of barium sulfate is reflected in the solubility product for the dissolution. This shows that a small amount of barium ions is found free in solution.

Calculation to find the concentration of barium

[ ] of products

isolate for 'x'

  • To limit the ability of barium sulfate to dissolve in solution and release toxic barium ions, sodium sulfate is added to it.

  • Sodium sulfate is extremely soluble in water, therefore releasing sulfate anion.

  • The elevated concentration of sulfate ions in solution restricts the dissolution of barium sulfate, therefore barium sulfate remains essentially intact, limiting the concentration of barium ions in the body
  • used to examine the gastrointestinal tract

  • this connects our knowledge of chemistry to the real world because it is used to diagnose structural or functional abnormalities in the GI tract such as:
  • cancer, tumours
  • hiatal hernia (upward movement of esophagus)
  • enlarged veins
  • muscle disorders or spasms
  • gastroesophageal reflux disease or ulcers (gastric acid from the stomach inflames the esophagus through reverse movements)

It is important to know the chemistry behind the use of barium sulfate in x-rays so that it is understood the harmlessness of the intake of barium sulfate into your body.

Barium sulfate suspensions also contain 0.10M sodium sulfate and uses the common ion effect to control the solubility of barium sulfate in solution.

common ion effect

Since barium ions are toxic to humans, we want to adjust conditions to ensure that the direction of the dissolution reaction favours the reactants.

Recall:

The common ion effect occurs when you add more of an ion that is already present in the equilibrium equation to restore balance.

Salt sodium sulfate will readily dissociate into sodium and sulfate ions, therefore increasing the concentration of sulfate.

Recall:

Le Chatelier's Principal - if conditions of equilibrium change, the process tends to do the opposite to cancel out the effect of the change

By Le Chatelier's principle, the system will respond to the presence of the common ion (which is sulfate, the ion present in both sodium sulfate and barium sulfate) by shifting the position of the dissolution equilibrium to the left (reactants). The solubility of the reactant barium sulfate will be further decreased by the presence of the sulfate anion.

Any questions?

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