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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Seeming discrepancy between pKa and corresponding Ka of methylamine

The first entry in PubChem for the $\mathrm pK_\mathrm a$ of methylamine is $10.657$ at $25\ \mathrm{^\circ C}$. My elementary understanding is that this would be found as the negative log of the $K_\...
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EQPt pH of a Monoprotic Acid-Base Titration: Product of Molarites Over Their Sum

Context The Henderson-Hasselbalch equation is as follows. $$pH=-\log\big(K_a\big)+\log\bigg(\frac{[A^-]}{[HA]}\bigg)$$ One may follow its derivation in order to understand how it came to be, yet ...
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How to calculate pH of the Na2CO3 solution given ambiguous Ka values

This is the exact question I faced on an exam. Calculate the pH of $\pu{0.05 M}\ \ce{Na2CO3}\ (\ce{H2CO3}: K_\mathrm{a,1}= 4\times 10^{-7},\ K_\mathrm{a,2}= 4.7\times 10^{-11})$ Solution $$\ce{...
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Calculating the pH of a solution of sodium carbonate

I've seen similar questions on this site, but I'm having trouble as my book said something else. For a $\pu{0.09989 M}$ solution of $\ce{Na2CO3}$, my book said: $$\ce{Na2CO3 + 2H2O -> H2CO3 + 2Na+ ...
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Find the half equivalence point

How to find the half equivalence point knowing the pH, molarity, titrant added at equivalence point? This a fairly straightforward and simple question, however I have found many different answers to ...
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147 views

Understanding the increase in pH of a buffer solution upon incremental additions of NaOH analytically

So let's say we have $200\ \mathrm{mL}$ of $1\ \mathrm M$ $\ce{CH3COOH}$ solution. In this solution we have the equilibrium $\ce{CH3COOH <=> CH3COO- + H+}$. To that we add $100\ \mathrm{mL}$ of $...
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Why does final pH value of buffer solution after addition of acid not depend on amount added?

I'm brushing up and the example in my book is against my intuition. A buffer solution contains 1.0 mol/L acetic acid and 1.0 mol/L sodium acetate. The solution is at pH = pKa = 4.75. What's the ...
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196 views

pH-dependency of the acidic dissociation of carbonic acid

I know the product of $\ce{CO2 +H2O}$ yields $\ce{H2CO3}$. This is a reversible equation so $\ce{H2CO3}$ goes back to $\ce{H2O + CO2}$. However, my question is: Is there a certain pH which will ...
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383 views

Titration of hydrochloric acid with sodium hydroxide

I have a question regarding titration of hydrochloric acid with sodium hydroxide. Assume you have a solution of NaOH with pH = 12. With this NaOH you titrate a HCl solution. Then, will the pH of the ...
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How do I calculate the amount of polyprotic acid and base needed to achieve a certain buffer pH?

e.g. Citric Acid and Trisodium Citrate $\ce{H3C6H5O7 <=>[ka_1] H2C6H5O7- + H+ <=>[ka_2] HC6H5O7^2- + H+ <=>[ka_3] C6H5O7^3- + H+}$ Using the definition of Ka and substituting for ...
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Numerical on acetic acid - sodium acetate buffer

Starting with 1 L of 2.0 M $\ce{CH3COOH}$, we wish to make a buffer solution of pH=4.00. Consider two ways to make the buffer: a) One way would be to add sodium acetate. How many moles must be added?(...
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pH value change with dilution

How does pH value change with dilution for the question shown in the picture? I expect the pH value to increase with dilution. Is there any case where the value remains same with dilution?
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calculating ph of a mixture of acids

I came across a question that couldn't find the answer to and i couldn't find the answer anywhere. The question is the following. You have a soltion created by dissolving HCN and HBrO in water (T = ...
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679 views

How to make a buffer using HClO

If we plan to prepare a buffer with the $\mathrm{pH}$ of $7.35$ using $\ce{HClO}$ ($\mathrm pK_\mathrm a = 7.54$), what mass of the solid sodium salt of the conjugate base is needed to make this ...
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Relating pH and buffer capacity

So, here is the equation for a weak acid - strong base pH curve And here is the expression gotten when the derivative of concentration of hydronium ions with respect to volume of base added is ...
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610 views

Calculating PH of solution after adding strong acid (equilibrium)

Consider the classic example when talking about acids and bases: Say you have 1M of $\ce{HCL}$ and you throw it into water, calculate the resulting pH (= concentration of $\ce{H3O+}$). The way this ...
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904 views

why the buffer capacity depends on the ratio of salt and acid in acidic buffer?

According to the Henderson–Hasselbatch equation when pH = Pka for any buffer solution then why we say that this is the best buffer?

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