What Range of PH Values Is Acidic?
The pH of a substance relates directly to the concentration in a solution of ions that make something acidic. It is a helpful way to quickly assess the acidity of a solution. While there is a rigorous scientific definition of acids, the pH scale allows anyone to easily determine if something is acidic.
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The pH scale
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Technically speaking, the pH of a substance is found by using the formula pH=-log([H+]). While this may be confusing, it is the basis of how the pH scale works. Since it is a logarithmic scale, it produces numbers that are easily evaluated from concentrations that are unwieldy. For instance, if you have a concentration of acid that is 3X10^9, the pH is 9.48. The large number is converted to an easily understandable one.
pH values
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The pH scale can range from negative numbers (very acidic) to numbers in the teens (very basic). Most pH tests range from 1 to 14, but in practice you can get a larger range of numbers. These are usually divided into three areas: pH <7 is acidic, pH = 7 is neutral, and pH>7 is basic.
A strong, nearly concentrated solution of acid can give you a pH of -1, or 0. However, any pH number less than 7 is considered acidic. -
Litmus paper
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To easily determine the pH of a substance, use litmus paper. This is a little strip of paper that changes colors upon contact with the substance. The color of the paper is then matched up with a set of standards that tell you what pH your substance is close to. In most cases, oranges and reds indicate acidic solutions.
Physical characteristics of an acid
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A pH value indicating an acid will tell you a few things about the physical characteristics of a solution. An acid will generally taste sour or bitter and have a chocking smell. The smell of vinegar is primarily due to the acetic acid in it.
Balancing act
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Acids and solutions of acids can be a delicate balance of molecules. Often the pH of a substance can be dictated by various equilibrium reactions taking place inside the solution. This balance can hinder some substances from taking on an acidic pH value, even if you add something that easily changes the pH of other substances. When the pH of a solution can be determined, you can know the precise amount of acid molecules present.
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