How can ph be negative

On the other hand, the hydrogen ion activity is higher for a concentrated strong acid than for a more dilute solution. This is because the solution contains very little water per unit of acid. This tends to make the true pH lower than the calculated value.

The key is to figure out which has a greater effect: the incomplete dissociation or the increased hydrogen ion activity. If the hydrogen ion activity wins out, the acid could have a negative pH. The pH of a 12M strong acid is negative using the pH equation. Use precise geolocation data. Select personalised content.

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Measure content performance. Develop and improve products. List of Partners vendors. Share Flipboard Email. Anne Marie Helmenstine, Ph. Chemistry Expert. Helmenstine holds a Ph. She has taught science courses at the high school, college, and graduate levels.

Facebook Facebook Twitter Twitter. The misconception that pH lies between 0 and 14 has been perpetuated in popular-science books, textbooks, revision guides, and reference books. In reality, their dissociation is also essentially an equilibrium process, though this only becomes apparent at surpassingly high concentrations.

As the solution becomes more concentrated, any additional acid cannot be as thoroughly solvated, and the chemical equilibrium begins to favor dissociation progressively less and less.

Hence, as the solution becomes increasingly saturated, the extent of dissociation begins to plateau and the hydrogen ion concentration approaches some practical upper limit. Other phenomena, such as the formation of distinct chemical species by self-ionization in a concentration-dependent manner further complicate things e.

Negative pH is actually very common. Take a concentrated solution of one of the strong inorganic acids i. This range is such that our normal calculations in lab can be worked out easily.

It is to be noted that this scale is at room temperature. If you increase the temperature then the limits changes. Hence we can see that the scale has shifted with temperature. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Is a negative pH level physically possible?

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