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Sodium hydroxide facts for kids

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Sodium hydroxide
Sodium hydroxide pellets on a glass dish

Sodium hydroxide is a strong chemical. It is also known as caustic soda. The word "caustic" means it can cause irritation or damage. This is why caustic soda can hurt your skin if it touches it. Its chemical formula is NaOH.

It is a base, which means it has a high pH level. Bases are the opposite of acids. Sodium hydroxide is often used to make solutions less acidic. For example, it can neutralize an acid.

When it is a solid, sodium hydroxide easily absorbs moisture and carbon dioxide from the air. It dissolves very well in water. When it dissolves, it makes the water warm. A solution of sodium hydroxide in water is called lye. Lye is used to make soap. It is also used to help clear clogged drains.

Sodium hydroxide works in two main ways to clear drains. First, it mixes with grease to create soap. Second, it helps dissolve hair. Hair can dissolve in a basic solution like lye.

How Sodium Hydroxide is Made

Sodium hydroxide can be made using a process called the chloralkali process. This process also creates chlorine and hydrogen gas.

First, a solution of sodium chloride (which is common table salt) is put through electrolysis. This means electricity is passed through the solution. Sodium hydroxide forms around the cathode. The cathode is a special part of the setup. At the cathode, water changes into hydrogen gas and hydroxide ions. The hydrogen gas is released. The hydroxide then joins with the sodium to form sodium hydroxide.

It is important to be careful when mixing sodium hydroxide with water. This process releases a lot of heat. The solution can splatter or even boil.

Here is a simple way to look at the chemical reactions:

  • 2Na+ (from salt) + 2H2O → 2NaOH + H2 (at the cathode)
  • 2 Cl- (from salt) → Cl2 (at the anode)

Images for kids

  • NaOH - drain-cleaner

    Sodium hydroxide sold in Hardware stores to be used as a drain cleaner.

  • Paint stripping with caustic soda

    Using caustic soda to remove paint.

  • Sodium hydroxide burn

    This image shows skin irritation caused by sodium hydroxide solution. Always be careful when handling chemicals.

See also

Kids robot.svg In Spanish: Hidróxido de sodio para niños

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