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What is pH?

Highlighted from a real textbook passage. Explained by Clicked.

Used in a sentence

Buffered solutions resist changes in pH even when small amounts of strong acid are added.

The reader highlighted one word in a textbook passage. Clicked broke down the concept “pH” into plain English:

Explained in three depths

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Overview

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pH measures how acidic or basic a liquid is, on a scale from 0 to 14 with 7 as neutral. Below 7 is acidic and above 7 is basic. Each step of one on the scale is a tenfold change, not a small notch.

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Detail

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Acids release hydrogen ions into a liquid, and pH counts how many are floating around, so more ions means a lower number. Each step down the scale means ten times more ions, so lemon juice at pH 2 is a hundred times more acidic than tomato juice at pH 4, not twice. The scale is compressed this way because the raw counts are unwieldy, spanning a range of about a hundred trillion. Human blood must stay between 7.35 and 7.45, and a drift of a few tenths either way is life-threatening. Blood holds that line with a buffer: a pair of dissolved chemicals, one that neutralises any arriving acid and one that neutralises any arriving base, before the pH can move.

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Analogy

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Earthquake magnitude. A magnitude 7 sounds only a little worse than a 6, but it shakes the ground ten times harder, and an 8 shakes a hundred times harder than the 6. The numbers stay small and calm while the shaking grows enormous, and pH compresses acidity the same way.

AI explanations may contain errors · Not professional advice

Same facts, different vibe — Slang mode 😎

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Overview

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pH is the acidity scale, 0 to 14, with neutral water sitting at 7. Lower means more acidic and higher means more basic. The trap is that each step is ten times, so pH 3 is a hundred times more acidic than pH 5. 😎

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Detail

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Acids dump hydrogen ions into a liquid, and pH is basically a headcount, so more ions means a lower number. The part that catches everyone: each step is ten times, so pH 3 is a hundred times more acidic than pH 5. Stomach acid sits around 1.5, roughly a million times more acidic than water, which is why it dissolves your lunch and why your stomach rebuilds its own lining nonstop. Your blood has to stay between 7.35 and 7.45, and a few tenths off is an emergency. It holds the line with a buffer: two dissolved chemicals, one grabbing any acid you throw at it and one grabbing any base, so the number barely twitches at lemonade. 😎

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Analogy

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Hot sauce labelled 1 to 5, where each number is ten times hotter than the one before. A 3 doesn't sting slightly more than a 2, it stings ten times more, and the 5 ends your evening. Tiny numbers, completely unhinged gaps between them.

AI explanations may contain errors · Not professional advice

Formal definition — The same term, explained the usual way

pH is defined as the negative base-ten logarithm of hydrogen ion activity, yielding a compressed scale on which each unit represents a tenfold concentration change. Physiological systems maintain narrow pH ranges through buffer equilibria, notably the bicarbonate system, which resists change upon addition of acid or base.

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