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# 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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### pH of a buffer made with boric acid and potassium dihydrogen borate

The Problem Calculate the pH of a buffer that is $\pu{0.200M}$ $\ce{H3BO3}$ and $\pu{0.122M}$ $\ce{KH2BO3}$. The $K_\mathrm{a}$ for $\ce{H3BO3}$ is $7.3\times10^{-10}$ What I Tried For each of ...
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### Dissolving Tylenol Science Experiment - why is it fastest in distilled water?

My son has a science experiment for class to dissolve Tylenol (325mg acetaminophen) in 3 different solutions (125 mL volume each): Distilled water Vinegar (1 part white vinegar to 4 parts water) Salt ...
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### How to calculate the amount of citric acid to neutralise the pH within wastewater?

We have an effluent tank, with a consent to discharge at between 5.5 - 11 pH, the tank holds 100000 liters of dirty water. When the pH reaches 10.5 we add citric acid to bring the pH down. How ...
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### What happens when 0.02 mole NaOH is added to a buffer solution?

I am asking this question for my son. (This question is related but we still have our confusions.) We have one liter buffer solution of 4.74 pH which contains 0.1 mole $\ce{CH_3COOH}$ and 0.1 mole ...
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### Why does pKw first decrease but eventually increase when temperature rises?

I understand the initial decrease in pKw. $\ce{Heat + H2O (l) <=> H+ (aq) + OH- (aq)}$ Temperature increases, reaction shifts to the right, so $\ce{H+} \text{ and } \ce{OH}$ ...
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### Slow acidification process

I'm trying to find a substitute of Glucono delta-lactone (GDL). This food additive is usually used to produce silk tofu. Because of its slow hydrolysis the pH decreases very smoothly, which results in ...
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### Why does an acid have a low pH value?

When study biology in class, I don't know how my teacher get to the topics on pH value. So, she says that pH stands for percentage hydrogen. Then, I thought there is something strange about it cause ...
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### Why does pOH increase when pH decreases?

Let's say you add $\ce{HCl}$ to water. The $\ce{H+}$ ion concentration increases and that causes a decrease in $\mathrm{pH}$. But why would the $\mathrm{pOH}$ increase? I can't see why added $\ce{H+}$...
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### What is the physical quantity/magnitude of pH?

I have a database to classify variables/parameters in water resources as follows: Variable: Precipitation (P); Quantity: Length; Units of measurement: mm (millimeters). Following the example, what ...
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### How can pKas differ across similar protons of the same atom?

For example, citric acid has three acidic protons, all of which are carboxylic acids. Despite being part of the same functional groups, they all have very different pKas. Why (and how?) is this?
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### How to calculate the pH of a buffer after HCl was added?

A buffer is made from $50~\mathrm{mL}$ of $1.0~\mathrm{M}$ benzoic acid, $K_a = 6.3\cdot10^{-5}$, and $50~\mathrm{mL}$ of $1.0~\mathrm{M}$ sodium benzoate. a) Calculate the pH of this buffer For this ...
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### What is the pH of kvass?

I know that it is less than 7.0, but would be nice to know exact value of pH of natural fermented kvass (not soda-like counterfeit). Another aspect is to know if kvass is more gentle than Cola (pH=2.5)...
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### Why does hydrogen phosphate act as a base?

Let's look at question c: a) Write a balanced equation for the reaction. $$\ce{2 NaOH + H3PO4 -> Na2HPO4 + 2 H2O (l)}$$ b) When some crystals of $\ce{Na2HPO4}$ were dissolved in water, ...
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### pH of sodium metasilicate anhydrous vs pentahydrate when dissolved in water

I'm not a chemist and don't remember much chemistry from school, so please forgive a naive question (I've read the Wikipedia article on sodium silicate though). I'm researching this topic to make ...
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