Friday, September 2, 2011

A5 Universal Indicator


Describe the use of universal indicators to measure pH of a solution

Universal indicator is perhaps the main way in which the pH of a solution is tested, this is because not only does it tell you whether the solution is an acid, alkali or neutral it also tells you how acidic or alkaline the solution is.

As you know each number on the pH scale is given a colour, ranging from deep red to deep purple. These colours represent the colours universal indicator goes when presented with such a chemical. For example putting universal indicator into an acid solution we may find that the indicator turns an orangey red and comparing with our pH scale we can easily see that this chemical has a pH of roughly 2. And obviously this works for alkalis too.

You must remember that Universal indicator solution is green on its own so when presented with a neutral solution it will stay green. But Universal indicator paper is often a yellow colour, so when presented with a neutral colour will change to be green.

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