Alkali
Definition and meaning of Alkali in chemistry.
An alkali is a soluble base that produces hydroxide ions (OH−) when dissolved in water. Alkalis have a pH greater than 7.
In more detail
Alkalis react with acids in neutralization reactions, forming water and a salt. They exhibit characteristic properties such as turning litmus paper blue, tasting bitter, and feeling slippery or soapy to the touch. Common alkalis include sodium hydroxide, potassium hydroxide, and aqueous ammonia solutions. These substances are distinguished from insoluble bases because of their solubility in water and ability to readily dissociate into ions.
Key facts
| Common Examples | NaOH, KOH, aqueous ammonia |
|---|---|
| pH Range | Greater than 7 |
| Indicator Test | Turns blue litmus paper |
| Field | General Chemistry |
Sodium hydroxide (NaOH), also known as caustic soda, is a widely used alkali in soap manufacturing, water treatment, and drain cleaners. When dissolved in water, it completely dissociates to produce sodium ions and hydroxide ions, making the solution highly basic, slippery, and caustic enough to cause chemical burns.
Frequently asked questions
What is the difference between an alkali and a base?
All alkalis are bases, but not all bases are alkalis. Alkalis are specifically bases that are soluble in water, whereas bases can be insoluble compounds that accept protons.
Why do alkalis feel slippery?
Alkalis feel slippery because hydroxide ions interact with the oils and proteins in your skin, breaking down their structure. This property is why alkali solutions are corrosive.