9

Because the acid and conjugate bases are equimolar - and because the equilibrium constant is small, obviating the need to solve a quadratic if you approached this in another way - the Henderson-Hasselbalch equation is: $$\pu{pH} = {\rm p}K_\mathrm{a} + {\rm log}_{10}\left({[A^-]\over[HA]}\right)$$ $$\pu{pH} = 4.74 + {\rm log}_{10}\left({0.2\ {\rm M}\over 0.2\...


6

The strength of permanganic acid that you quote, combined with that of potassium hydroxide as a base, would guarantee that pure potassium permanganate is neutral in aqueous solution. But commercially prepared potassium permanganate is made in the presence of alkali, the use of potassium instead of sodium arising from the fact that the reaction scheme does ...


4

$ \begin{align} (n_{\ce{NaOH}})_i= \pu{0.2 mmol}\\ (n_{\ce{HCl}})_i= \pu{0.1 mmol}\\ (n_{\ce{NaH2PO4}})_i= \pu{0.1 mmol}\\ (n_{\ce{Na3PO4}})_i= \pu{0.05 mmol} \end{align} $ At first the $\ce{NaOH}$ will react with $\ce{HCl}$ as per the following reaction: $$ \begin{align} \begin{array}{ccccc} \ce{NaOH} & + & \ce{HCl} & \ce{->} & \ce{NaCl} ...


3

The acid strength of each compound can be explained, but the acidity order is much more difficult to compare, because the two compounds are only remotely connected. It is misleading to conclude that the mere presence of a phenyl group somehow connects these molecules. The similarity of the pK$_a$s is likely a coincidence. The question needs a clear ...


3

The reason provided by ML cannot explain the difference in acidities since the +I effect doesn't come into play normally for the para positions. A more likely reason is hyperconjugation (or no bond resonance) where the number of hydrogens directly attached to the benzyl carbon decreases as it goes from P to S. This means that the number of destabilizing ...


3

Likely, you'd get a yogurt-like mixture, and, eventually, cottage cheese: "Cheesemakers create cottage cheese by heating... milk, then mixing it with an acid -— which could be lactic acid-producing bacteria cultures or an acid like rennet, vinegar, or lemon juice. This acid causes the curds and whey to separate." There are differences between just ...


3

Probably. Lactic acid bacteria produce other volatile compounds such as acetaldehyde and diacetyl that could be perceived as off-flavors. Both where fermentation is the objective and in the case of spoilage, the VOC profile can vary with the identity of the responsible bacteria but also of the milk and its treatment. For instance, in Ref. 1 they discuss the ...


2

$\mathrm{p}K_\mathrm{a}$ is an indicator of acidity constant and it is defined as the negative decimal logarithm of the constant itself: $\mathrm{p}K_\mathrm{a} = -\lg K_\mathrm{a}.$ So, (non-formal) the higher is the dissociation, the lower is $\mathrm{p}K_\mathrm{a}.$ Terminal alkynes have general formula $\ce{R-C#CH},$ where $\ce{R}$ is a radical. The ...


2

Ionic product of $\ce{H2O}$ is changing with temperature. It is $14.94$ at $0$°C, $14.17$ at $20$°C, $13.83$ at $30$°C and $12.26$ at $100$°C. So the pH of pure water is $7.47$ at $0$°C, $7.08$ at $20$°C, $6.92$ at $30$°C, and $6.13$ at $100$°C


2

The acidity of benzoic acid $(\ce{C6H5-COOH})$ and its substituted derivatives, $\ce{R-C6H4-COOH}$ $(e.g., \ \ce{4-NO2-C6H4-COOH})$ have been studied extensively using the Hammett Equation. Similarly, acetic acid $(\ce{CH3-COOH})$ and its substituted derivatives, $\ce{R-CH2-COOH}$ $(e.g., \ \ce{Cl-CH2-COOH})$ have been studied extensively as well using ...


2

This question is, at best, flawed. The most acidic protons on the structure provided are not any of the labeled OH protons. Rather, the most acidic position is the one I have drawn a rectangle around below. Deprotonation at this position produces an anion with a resonance contributor in which both rings are aromatic. The circa 150 kJ/mol resonance ...


1

The issue as I can see it here is a simple misunderstanding that can rectified: $K_\mathrm a$ is a constant even if $\ce{[A]}$ is not. (which is how it was defined) The definition of $k_\mathrm a$ is as follows: $K_\mathrm a$ , the acid ionization constant, is the equilibrium constant for chemical reactions involving weak acids in aqueous solution. Nowhere ...


1

For alkyl groups attached to the phenol ring, there are two main points that your reasoning does not take account of - Inductive effect is distance dependent. As the distance increases, its effect becomes very small. Even if the group were near, the general trend is that hyperconjugation has stronger effect than inductive effect. You can refer the ...


1

Taken from my answer here: Comparing methane and acetylene shows a difference of $\approx 20$ $\mathrm pK_\mathrm a$ units Comparing $\mathrm p K_\mathrm a$ of phenol($10.0$) and methanol($15.5$), we see that the presence of one resonating ring only produces a 5.5 $\mathrm p K_\mathrm a$ difference. Resonance in triphenyl system is effectively only one ...


Only top voted, non community-wiki answers of a minimum length are eligible