Meaning & use
hydroxide
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Meanings
nouncountablechemistry
A chemical group made of one oxygen and one hydrogen atom together, carrying a negative charge (OH−).
Grammar: Countable when referring to the ion itself; the formula is usually written OH−.
Patterns
- a hydroxide ion
- hydroxide ions in solution
When sodium hydroxide dissolves in water, it separates into sodium ions and hydroxide ions.
The hydroxide ion is basic because it can accept a proton from an acid.
A high concentration of hydroxide ions makes a solution strongly alkaline.
nouncountable or uncountablechemistry
A compound that contains the OH− group, such as sodium hydroxide or calcium hydroxide.
Grammar: Countable when naming a specific compound (a hydroxide), uncountable when talking about the substance in general.
Patterns
- sodium hydroxide
- a metal hydroxide
- hydroxide solution
Sodium hydroxide is a strong base often used in soap making.
Calcium hydroxide is added to soil to reduce acidity.
The lab stores hydroxides separately from acids.
Word forms
| plural | hydroxides |
|---|
Common combinations
- sodium hydroxide
- Sodium hydroxide is a common laboratory base.
- hydroxide ion
- The hydroxide ion has a negative charge.
- metal hydroxide
- A metal hydroxide often forms when a metal reacts with water.
- hydroxide solution
- Always wear gloves when handling a hydroxide solution.
Word family
- hydroxyl noun
- The –OH group when it is attached to a carbon atom in an organic molecule.
- hydrated adjective
- Describing a substance combined with water molecules, not to be confused with hydroxide.
Commonly confused: hydroxide or hydride? hydroxide or hydrogen?
hydroxide vs hydride
A hydride contains hydrogen bonded to a metal or another element, while a hydroxide contains the OH− group.
hydroxide vs hydrogen
Hydrogen is the element itself (H); hydroxide is a group of oxygen and hydrogen atoms with a charge.
Practice
Which statement about hydroxide is correct?
Choose one answer.
Hydroxide is OH−, a negatively charged group made of oxygen and hydrogen. It is not positive (A), not defined by carbon (C), and not the same as a hydrogen ion (D).
Make it your own
Write a sentence using “hydroxide”, then check it and compare it with the examples above.