New answers tagged acid-base
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I strongly suspect a typographical error, the concentration of KOH should be 0.25 M. If that's the case, you should be able to find a molecular weight for the R group that does correspond to $\ce{C_nH_{2n+1}}$ for some whole number $n$ (you are to figure out $n$). You will then need to pick the isomer that properly has a methyl branch and name the compound ...
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NH4CN, in fact, does not dissociate completely! We write c below the respective dissociated ions to represent the concentrations at t=0 and t=teq (time at equilibrium) if there was complete dissociation. You should take in count that h stands for the degree of hydrolysis, that is, how much salt would undergo hydrolysis. Answering your second question, we ...
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Reactions that are in equilibrium will have both reactants and products present. However, the interesting thing about dissolution reactions is that a solution that is undersaturated (below its solubility limit) will not be in equilibrium (i.e. no solid exists). So unless the example you are talking about specified that the concentration of salt is above the ...
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The curves are rather obtained clinically, statistically evaluating diagnose, symptoms and results of clinical lab tests.
Metabolic curve follows malfunctioning metabolism keeping too low ( m. acidosis ) or too high ( m. alkalosis ) level of bicarbonate.
Respiratury curves follows states of too intense breathing ( r. alkalosis ) or too shallow breathing ( r. ...
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This is a purely anecdotal example: I once set up a target at a shooting range which involved mixing lye. My hands were damp because I had just wiped off some snow, which provided a tacky surface for some lye to stick against.
About 2-3min later, it itched. About 10min later, it felt like an open wound, because it was; the skin had turned into a "soup&...
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Your question and your formulas are really asking about two different things.
Let's look at your formulas first.
$$\ce{H2O + HA <=> H3O+ + A-},\tag{R1}$$
$$\ce{HA <=> H+ + A-}?\tag{R2}$$
For R1 the equilibrium equation should be:
$$\mathrm{K_a} = \dfrac{\ce{[H3O+][A-]}}{\ce{[H2O][HA]}}\tag{Eq-1}$$
but for R2 the equilibrium equation should be:
$$\...
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As noted in the comments, lye burns are very damaging to skin and especially mucous membranes. This damage can be drastically reduced if the lye is washed off as quickly as possible.
One reason that these solutions are considered particularly dangerous is that there is no discomfort immediately upon contact (in contrast to acids, which tend to produce ...
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To answer my own question:
Using either the diffusion limited or the literature values of the acid-base neutralisation (Baldyga et al., Non-isothermal Micromixing in Turbulent Liquids: Theory and Experiment), I was able to simulate the $\mathrm{pH}$ as a function of time by making the simplifying assumption of equal diffusion coefficients of proton and ...
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For a weak acid $\ce{HA}$ with acid constant $K_\mathrm{a}$:
$$\ce{HA + H2O <=> H3O+ + A-} \tag1$$
$$K_\mathrm{a} = \frac{[\ce{H3O+}][\ce{A-}]}{[\ce{HA}]} \ \Rightarrow \ [\ce{H3O+}] = K_\mathrm{a} \cdot \frac{[\ce{HA}]}{[\ce{A-}]} \tag2$$
Taking $-\log$ of both side of equation $(2)$:
$$-\log [\ce{H3O+}] = -\log K_\mathrm{a} -\log \frac{[\ce{HA}]}{[\...
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Acid (Brønsted–Lowry Acid) is a substance that gives away its $\ce{H+}$, but the environment should be able to accept that $\ce{H+}$. After it accepted it - the acid (which is now its conjugate base) can accept it back. There are 2 extremes:
The environment already has plenty of $\ce{H+}$ already. So even if acid gives its $\ce{H+}$ to the environment, it ...
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I’m an undergrad chemistry major, and I know some about the subject. The reason that people (falsely) believe that lemons somehow “turn alkaline” in the body is because drinking a lot of lemon juice slightly raises the pH of urine. The real reason this occurs is because the citric acid forms a buffer with citrate (which is found in the renal system I believe)...
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As a teacher, you should lead by example how to engage with chemicals respectfully, as a professional. Which neither is to be fearful, nor to be sloppy and negligent for their potential hazards. This includes to plan ahead, to limit exposure to dangerous goods (like concentrated HCl is), to use protective gear, safe manipulation of the chemicals in response ...
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I think it is enough to watch the Safety Data Sheet to understand. I found this one browsing on the internet:
Safety data sheet of a Chloridric acid manufacturer
On section 11 you can find: ATE US (gases): 1560.000 ppmV/4h. ATE means "Acute Toxicity Estimates".
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Usually a pure acidic molecule like HCl gives one proton $\ce{H+}$ to a base like NH3 or $\ce{CH3COO-}$, and the proton once fixed on the base gives a new species which is $\ce{NH4^+}$ or $\ce{CH3COOH}$. And that's all what's happening. With water, it is a bit different. The $\ce{HCl}$ molecule starts by giving one proton $\ce{H+}$ to one $\ce{H2O}$. This ...
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You can't compare them at all. If the ortho form dissociates at all then the carboxylate ion combines with the aldehyde function, forming a lactone ring. See Wikipedia.
This question invokes a comparison of the similarly structured nitrobenzoic acids. There the ortho compound is found to be strongest, beating its isomers by about one $pK_a$ unit and ...
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It’s possible if the known concentration to use the solution to make soap! Just a thought. I make soap at home all the time with sodium hydroxide solutions
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The strength of Lewis acids relative to your Lewis base has been commented on. A fuller answer to your question needs to include the Lewis acid you are considering.
The original Bronsted-Lowry theory of comparing acidity and basicity, or acids and bases, involved $\ce{H^+}$ and $\ce{OH^-}$ and the transfer of a proton.
The broader Lewis theory allowed ...
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When the ratio of conjugate base concenteration to conjugate acid concenteration is more than 1000 , we say that the dissociation of acid is complete.
According to Henderson–Hasselbalch equation the ratio of conjugate base concenteration to conjugate acid concenteration gets more than 1000 , when PH-PKa is more than 3.
For strong acids, this ratio is more ...
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Based on the three step mechanism you have provided, what if the slow step is your step 3 which is H + H --> H2 so rate law is now k3[H]^2. Since H is an intermediate, you can substitute for this intermediate from earlier steps and you will end up with
Rate = (k3.k1.k2.[Mg][H+]^2)/[Mg2+] and if [Mg]/[Mg2+] is constant as the reaction of a solid always ...
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First of all, the indicator does not change colour instantaneously at $\mathrm{pH = pK_a}$. The indicator is a different colour than it's conjugate base, and exists in an equilibrium with it in solution. For the colour change to be noticed, the concentration of the base has to be at least 10 times more than that of the conjugate acid, or vice versa. This is ...
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Chromium(III) ions are like Fe(III) and Al(III) ions. Exactly like aluminum and ferric carbonates, chromium(III) carbonate does not exist in aqueous solution. In principle it could be obtained according to $$\ce{2 Cr^{3+} + 3 CO3^{2-} -> Cr2(CO3)3}$$ But like with the aluminum and ferric carbonates, the chromium carbonate is immediately destroyed ...
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The two hydrogen atoms are acidic, but things change after one of them is lost. But I think that the question was aimed at the acidity of either of the hydrogen atoms and they are equivalent, so let's see why:
As you can see in the given figure that after abstraction of $\ce{H+}$ the conjugate base can resonate to attain aromaticity. It is this stability ...
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An oxidizing acid is a Brønsted acid that is a strong oxidizing agent.
All Brønsted acids can act as oxidizing agents, because the acidic
proton can be reduced to hydrogen gas."
The whole sentence is written in a very convoluted fashion, and it is partially wrong as well. Someone should improve this Wikipedia section.
All they are saying is that strong ...
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All acids are oxidizing. They are all able to oxidize metals $\ce{M}$ whose redox potentials are negative with respect to hydrogen, like zinc $\ce{Zn} ~(E° = - 0.76~\mathrm V$), iron $\ce{Fe}~ (E° = -0.41~\mathrm V)$, and magnesium $\ce{Mg} ~(E° = -2.37~\mathrm V)$. The reaction produces some hydrogen gas $\ce{H2}$ and the metallic cation $\ce{M^{z+}}$. But ...
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The definition of oxidation and reduction are
Oxidation is the loss of electrons or an increase in the oxidation state of an atom, an ion, or of certain atoms in a molecule.
Reduction is the gain of electrons or a decrease in the oxidation state of an atom, an ion, or of certain atoms in a molecule.
By this definition a $\ce{H+}$ ion can gain an electron ...
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Both the predictions are good. The NO2 will actually be an effective electron withdrawing group, and the lost of that H will stabilize the compound (if there is and NO2 on it). It is also important to rescue, that both effects will be stronger just on para or orto position. You can make the different structures to check it.
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Cells of fish contain proteins, and proteins are made of long chain of amino-acids, linked together by peptide bonds. In the presence of an acid (like phosphoric acid in your experiment or hydrochloric acid in our stomach), the peptide bonds are destroyed and the free aminoacids are released, so that they can be immediately assimilated by living organisms, ...
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Aeration does not seem to be the way to go.
If there are no other ions in the water, electrolysis (Kolbe reaction) would convert the $\ce{HOAc}$ to ethane and carbon dioxide:
$$\ce{2CH3CO2^- -> 2e^- + 2CO2 + H3C-CH3}$$
This process could probably be arranged to be done in a pipe with electrodes on the sides, so that the water was treated as it was used, ...
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Acetic acid does not form an azeotrop with water and is less volatile than water. So aeration of water would do the opposite - enriching of water by acetic acid due preferred evaporation of water.
Reverse osmosis should help, perhaps after neutralization to be mostly in acetate form.
The question is, if it is worthy the troubles. The cheaper, easier and ...
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