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pH= -log [H + ] Units of [H+] mol per litre Then why pH has no units?

pH= -log [H+]


Units of [H+] mol per litre


Then why pH has no units?

Grade:11

2 Answers

aditya suman
39 Points
13 years ago

pH has no unit because it is a logarithmic value of H+ions

Concentration itself does have units, but pH really only looks at the power (or exponent) of the concentrations. And, for that reason the unit doesn't carry.


For example:

pH = - log [H30+] (mathematical definition)
= negative logarithm of the hydronium ion concentration.

What this means is that if a solution has a concentration of 10-7 M [H30+] or (0.0000001 moles per litre of the hydronium ion), the negative log of this number = 7. Therefore the pH = 7.

But it's not 7 moles per litre or 7 moles or any other transferable unit. It's just 7.


Ajay Kumar
34 Points
13 years ago
pH has no unit because it's a it's a logarithmic scale, not a measurement like grams or degrees

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