Acids can gradually wear away and destroy almost everything they touch. All are soluble in water, and their strength is measured by their potential of Hydrogen.
The potential of Hydrogen scale runs from 1 to 14. One is extremely acid, 7 is neutral, and 14 is very alkaline (the opposite of acid).
The potential of hydrogen content of a liquid is measured with a potential of Hydrogen metre or with Universal Indicator paper, such as litmus. A strong acid turns the indicator paper red, while a neutral liquid turns it green. Strong alkaline liquids turn the indicator purple.
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