Universaalindikaatori värviskaala
Indicators and the pH scale
Solutions of acids are said to be acidic, and solutions of alkalis are said to be alkaline. If a solution is
neutral, it is neither acidic nor alkaline.
Indicators are substances that change colour when they are added to acidic solutions or alkaline solutions.
You can prepare homemade indicators from red cabbage or beetroot juice - these will help you see if a
solution is acidic or alkaline.
Litmus and universal indicator are two indicators that are commonly used in the laboratory.
Litmus
Litmus indicator solution turns red in acidic solutions and blue in alkaline solutions - and it turns purple in
neutral solutions.
Litmus paper is usually more reliable, and comes as red litmus paper and blue litmus paper. The table shows
the colour changes it can make.
Red Litmus Blue Litmus
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