6

First off, I've learnt that stronger acids produce weaker conjugate bases (through Brønsted–Lowry acid–base theory). That is correct. Then I looked at the $\mathrm{p}K_\mathrm{a}$ values of $\ce{HF}$, $\ce{HCl}$, $\ce{HBr}$, and $\ce{HI}$ and came to the conclusion that $\ce{HI}$ is the strongest among them and that explains why $\ce{I^-}$ is the weaker ...


4

If the reaction is heterogeneous (multiple phases involved), mechanical agitation helps. If the reaction is homogeneous (all reactants and products in the same phase), mechanical agitation usually does not help. An exception is when the process is auto-catalytic (i.e. starts in one corner and then propagates). In the example mentioned, agitation will help ...


3

At the molecular scale, a reaction will not become faster by stirring or agitation. At larger, macroscopic scale you may however increase the overall rate because agitation mixes the reactants with each other and hence increases the propability over time that they are exposed to each other. Especially in the case of heterogenous reactions like the one ...


3

in your question formulation, you have forgotten to take into account $\ce{H2O2}$ is a weak acid. The title should rather be: Neutralisation between calcium hydroxide and 30% hydrogen peroxide" Unless $\ce{Ca(OH)2}$ was in excess over $\ce{H2O2}$ - and it was said it was not - $\mathrm{pH}$ would be always significantly lower than pH of the hydroxide. $$\...


2

The Henderson-Hasselbalch relationship describing each ionizable group is: $$\mathrm{pH} = \mathrm{p}K_\mathrm{a} + \log \frac{\ce{[A-]}}{\ce{[AH]}}$$ We can solve for the ratio: $$10^{(\mathrm{pH} - \mathrm{p}K_\mathrm{a})}= \frac{\ce{[A-]}}{\ce{[AH]}}$$ However, we really want the fraction of protonated among the total (not the ratio of deprotonated ...


2

Ascorbic acid may serve as antioxidant preservative, but not as antimicrobial preservative. Unless it is present in comparable amount as added acetic acid and lactic acid formed by fermentation, but it would keep it redundant.


2

Second period nonmetals form much stronger bonds with hydrogen than their heavier congeners and so tend to bind more strongly with protons than we might otherwise expect. Not only is fluoride ion a stronger Bronsted-Lowry base than chloride ion (and heavier halides), so are hydroxide ion versus hydrosulfide ion and ammonia versus phosphine. The last pair ...


2

I have worked on a computational project where I had to study the sites of deprotonation in this molecule: When deciding between mechanisms I had to consider both thermodynamic and kinetic. For example, I had this case: deprotonations of two different hydrogens(bond with N Blu atoms in the picture)were similarly thermodynamically favored (similar free Gibbs ...


1

I don't know the reason, but I can describe the trend (source: http://cactus.dixie.edu/smblack/chem2310/summary_pages/pka_chart.pdf): Protonated ketones have a pKa of about -7. Protonated ethers have a pKa of about -4 and protonated primary alcohols of about -2. Comparison to hydronium in water is difficult, but in DMSO, hydronium is more acidic by about 2 ...


1

Below a more general approach. Suppose that we have two weak acids $\ce{HA}$ and $\ce{HB}$. The initial concentrations are $C^0_\ce{HA}$ and $C^0_\ce{HB}$, and their constants are ${K_\ce{a}}_\ce{(HA)}$ and ${K_\ce{a}}_\ce{(HB)}$. Suppose yet that volumes, $V_\ce{HA}$ and $V_\ce{HB}$, are additives. So we have: Reactions $$\ce{HA + H2O <=> H3O+ + A-}...


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