What is Sodium Hydroxide? - Formula & Reactions

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  • 0:01 What is Sodium Hydroxide?
  • 1:26 Reactions Involving…
  • 3:27 Lesson Summary
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Lesson Transcript
Instructor: Elizabeth (Nikki) Wyman

Nikki has a master's degree in teaching chemistry and has taught high school chemistry, biology and astronomy.

While handling sodium hydroxide can be dangerous, knowledge of sodium hydroxide can be enriching. Learn what sodium hydroxide is, its formula and about some chemical reactions involving sodium hydroxide in this lesson.

What is Sodium Hydroxide?

Sodium hydroxide is a powerful chemical with many aliases: NaOH, lye and caustic soda. Sodium hydroxide is often the active agent in cleaning solutions, but it is also used in the manufacturing of products like textiles, cellophane, and paper. This chemical can be very dangerous and can severely damage materials. Humans should avoid contact with sodium hydroxide without protection because it can cause severe burns to the skin and serious tissue damage if gotten in the eyes or inhaled.

Sodium hydroxide is represented by the chemical formula NaOH. It is an ionic compound because it is made of a metal ion, sodium (Na+) that is attracted to a nonmetal ion, hydroxide (OH-). When it is a solid, it is white and it has a high melting point of 604.4 degrees Fahrenheit. Though it has a high melting point, sodium hydroxide dissolves in water extremely well. When dissolved in water it is clear.

Sodium hydroxide is also a strong base, which is a compound that splits apart in water to make many hydroxide (OH-) ions. When dissolved in water, sodium hydroxide has a very high pH and feels very slippery. Generally, sodium hydroxide is most corrosive when it is dissolved in water.

Reactions Involving Sodium Hydroxide

Dissolving In Water

In water, sodium hydroxide breaks apart completely to yield one sodium ion and one hydroxide ion. This process is represented by the equation seen here. While this process is not a chemical reaction, it is still a very important property of sodium hydroxide.

Dissolution of sodium hydroxide

Reactions With Acids

Sodium hydroxide will react with acids to produce a water and an ionic compound. In this type of reaction, the hydroxide from sodium hydroxide reacts with the hydrogen ion in the acid, making water. The rest of the acid combines with the sodium ion from sodium hydroxide to make an ionic compound. The reaction between sodium hydroxide and hydrochloric acid can be seen here, as well as a reaction showing how sodium hydroxide reacts with acids in general.

sodium hydroxide reacts with acid

Reactions With Dissolved Metals

Sodium hydroxide will react with certain dissolved metals to make a solid. This type of reaction is very useful if the dissolved metals are toxic or need to be removed from the solution. Solid chemicals can be filtered out of a solution a number of different ways. In this reaction, dissolved copper reacts with sodium hydroxide to make solid copper(II)hydroxide and sodium ions. The blue colored copper(II) hydroxide can then be removed from the solution.

sodium hydroxide and copper

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