# Questions tagged [ph]

pH (or the potential of hydrogen) is a scale used to measure how acidic or basic an aqueous solution is.

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### How does acid damage skin? [closed]

As I understand it, acids are substances which have a high concentration of H+ ion which makes acid an acid. When interacting with our skin, acid can damage it. How does this concentration of protons ...
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### Why would the pH of a solution not be 7 at the equivalence point of an acid-base titration? [duplicate]

Is it because the new substance formed might be acidic/basic ? The internet defines this point as when the number of moles of the acid equals the number of moles of the base. But if we have for ...
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### How much citric acid do I need to add to bring pH down from 4.8 to 4.2?

It has been a number of years since I did chemistry calculations. I would like to know how much citric acid (powdered form - assuming it is 100% anhydrous) to add to a food product to reduce the pH ...
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### Finding ions in water samples

So for a school chemistry assignment I was given 5 water samples and a bunch of different reagents to help me find out what was in the solutions. I'm stuck on two. The first one had a pH of 7 and ...
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### Calculating pH of solution of phosphoric acid and ammonia

What is the $\ce{pH}$ of the solution created when $\ce{50ml}$ of $\ce{0.2M}$ $\ce{H3PO4}$ is mixed with $\ce{50ml}$ of $\ce{0.4M}$ $\ce{NH3}$? This problem can be approached rigorously. That's what ...
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### What is causing the buffer region in a weak acid - strong base titration?

For the buffer region in this, why does it stop the pH from increasing? At the start: $$\ce{CH3COOH + NaOH -> CH3COONa + H2O}$$ Which means there will be a high amount of salt in the solution, ...
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### Litmus paper reactions for mixed solutions [closed]

I am wondering what could cause my litmus paper to first react to the alkaline. turning blue, and then changing to an acidic red color?
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### Acid-Base buffer question

Calculate the change in pH of a buffer made by combining $\pu{500 ml}$ of $\pu{0.1 M}$ $\ce{CH_3CH_2COOH}$ and $\pu{500 ml}$ of $\ce{CH_3CH_2COONa}$, when $0.04$ moles of $\ce{NaOH}$ is added to the ...
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