Base
A base is a substance that gives hydroxide ions in water and shows basic behaviour such as turning red litmus blue.
Practice This ConceptMain explanation
Teacher explanation
Bases are the opposite side of the acid-base pair in school chemistry. They usually have pH above 7 and often feel slippery or soapy when dissolved in water. Common examples include sodium hydroxide and soap solution. Bases are important in cleaning, manufacture, and neutralisation reactions.
Example
Soap solution is basic. It turns red litmus blue and has a pH above 7.
Simple analogy
Base: red to blue, pH rises.
Common confusion
Students often think every slippery liquid is an acid or that bases only appear in laboratories. Many everyday cleaning solutions are basic.
Exam tip
When you write about a base, mention hydroxide ions, litmus change, and one example together for a strong answer.
Answer writing and exam use
1-mark use
Write the exact meaning of base in one clean line.
2-mark use
Define base and add one example or condition.
3-mark use
Explain base, show the method or example, and mention the common mistake.
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