New answers tagged acid-base
2
Rather, all depends on what aspects or criteria you evaluate.
If the compound fits criteria for salts, it is a salt.
If the compound fits criteria for acids, it is an acid.
If the compound fits criteria for bases, it is a base.
And the main point is - these categories are not mutually exclusive.
Additionally, there are 2 meanings for an acid/base.
Fitting ...
4
With a lot of assumptions, 0.5 M is a reasonable answer.
Here are the holes you have to fill in.
If it is a titration of NaOH and HCl, it is probably an acid/base titration where we stop the titration when the pH is neutral.
Titrations are often performed to figure out the concentration of a solution. You would titrate a smaller sample of the solution to ...
2
The formula $$C_1 \times V_1 = C_2 \times V_2$$
should never ever be used for titrations calculations. It fails miserably in most of the cases (e.g. titration of sulfuric acid with NaOH). This formula only works when the concentrations are in normality, which is considered an obsolete unit in modern chemistry. The proper use of this relation is for ...
1
However, I cannot see in any way how NaOH fits the Brønsted-Lowry definiton of a base.
Here are the two chemical equations that show you how the hydroxide anion present in an aqueous NaOH solution acts as a Brønsted-Lowry base:
$$\ce{OH-(aq) + H3O+(aq) <=> H2O(l)}\tag{1}$$
This shows that adding NaOH to water lowers the hydrogen ion concentration (i.e....
3
Let me analyze your sentences gradually, and try to correct the numerous mistakes.
Your teacher says that "before it is $\ce{NaOH}$, it was $\ce{NaO^-}$". No. First $\ce{NaO-}$ does not exist and cannot exist. Second NaOH has not been created out of an ion. Sodium is usually produced from the sodium metal after reaction with water according to : $$...
0
In short, $\ce{HNO3}$ is an oxidizing acid, so the destruction of the oxide layer competes with formation of new oxide. Something like this:
$\ce{Al2O3 + 6H+ -> 2Al^3+ + 3H2O}$
$\ce{2Al + 2Al^3+ + 6NO3- -> 2Al2O3 + 6NO2}$ (<-- maybe incorrect)
From Wikipedia:
Although chromium (Cr), iron (Fe), and aluminium (Al) readily dissolve in dilute nitric ...
1
Neutralization vs Solvation vs Dilution:
Semantically, the reaction of acid or base with water is (usually) solvation and dilution, not neutralization. Pure water $\ce{pH}$ (at $\pu{25^{\circ}C}$) is always 7, i.e. neutral.
When you add an acid to water, you are dissolving the acid. The formation of $\ce{H3O+}$ ions necessarily lowers the $\ce{pH}$, away ...
2
An acid/base neutralization will create a salt + water. is rather a secondary/junior high school teaching.
It is rather
$$\ce{AcidA + BaseB <=> BaseA + AcidB}$$
E.g.:
$$\ce{NH3(base) + H2O(acid) <=> NH4+(acid) + OH-(base)}$$
When strong bases or acid dissolve in water, they completely dissociate:
$$\ce{HCl(g) + H2O ->[H2O] H3O+(aq) + Cl-(aq)}...
0
I think there is a misunderstanding between Keq and Ka:
for $\ce{H3O+ + H2O <=> H3O+ + H2O}$:
$$K_{eq} = \frac{[\ce{H3O+}]*[\ce{H2O}]}{\ce{[H3O+]*[H2O]}} = 1$$
however $K_\mathrm{a} = K_{eq}*[\ce{H2O}] = \ce{[H2O]}$
therefore $K_\mathrm{a}(\ce{H3O+}) = [\ce{H2O}]$
p$K_\mathrm{a}(\ce{H3O+}) = -1.74$
2
We really need to think carefully about a lot of things when thinking about acid/base reactions: charge, resonance/aromaticity, electronegativity, hybridization, and occasionally things like sterics (things like proton sponge) or reversibility (for instance where one product is emitted as a gas like in the case of NaH). In many cases these factors are ...
3
Your instructor is right, up to a certain point. There are factors that are more important (the atom to which it is bound) and factors that are less important (resonance, etc.), and it's good to be able to order these relative factors. The devil is in the details, though. If your resonance stabilisation is strong enough (and in this case it is) then it can ...
2
Acetic acid can be decomposed by methane-producing bacteria. Note that the citation is for soil bacteria, but these methanogens can be found almost anywhere. Indeed, there is an entire microbial community in vinegar, including nematodes (worms). The more "natural" the product, the more organic material to nourish the microbes and to speed ...
1
During titration of small amounts of acids, the molar amount of the indicator in 1-2 drops of $\pu{1 \%}$ indicator solution may not be negligible compared to the acid molar amount, affecting the result.
So for that cases, $\pu{0.1 \%}$ solution is used, to be able to dose smaller indicator amounts.
As the phenolphalein molar mass is about $M=\pu{318 g/mol}$,...
2
In a weak acid $\ce{HB}$ solution, with a nominal concentration $c$, a tiny amount of its molecules are dissociated into $\ce{H^+}$ and $\ce{B^-}$. Let's call this concentration $[\ce{H^+}]$ = $\ce{[B^-]}$ = $x <<c$, so that the following approximation can be made : $c - x$= $c$. The dissociation equilibrium constant $K_a$ of this weak acid $\ce{HB}$ ...
-1
The pH can be measured vs. the amount of $0.1$ M NaOH added to your solution with a pHmeter. Then two titrations would be visible : first the titration of dihydrogenphosphate ($p\ce{K_a = 7.21}$) and then the titration of ammonium ($p\ce{K_a = 9.22}$). If you don't have a pHmeter, you would probably use a colored indicator. But the end of the first titration ...
9
As pointed out by Maurice and myself, the argument provided in the answer by iad22agp is rather incorrect. Sulfuric acid is a dehydrating agent just because it is available in concentrated form whereas rest of the common acids like HCl(aq) are not. No, it is not a concentration effect. First of all, it is not possible to have HCl(aq) more concentrated than ...
1
to prepare a 100 mM ammonium acetate solution at pH 9, you’d first prepare a 100 mM ammonium acetate, and then add ammonium hydroxide dropwise until the desired pH was achieved.
Well, this procedure is good enough for a rough screening solution- call it a quick and dirty method. The main issue is that one would not prepare a solution of 100 mM ammonium ...
0
A complex of lithium ion with lithium hudroxide is known as the salt $\ce{[Li2OH]^+[ClO4]^-}$ [1]. As with the hydronium salt, this requires an essentially nonbasic cation; with a chloride counterion a double salt is obtained with no evidence of a complex cation. From the abstract (some evident faults in translation from Russian jave been corrected):
An ...
1
Both water samples ( assuming pure water ) would theoretically end up slightly acidic with $\mathrm{pH} \approx 5.6$, but the carbonated one after long time. Tap water would have its baseline $\mathrm{pH}$ determined by its $\ce{CO2(aq)/HCO3-(aq)}$ $\mathrm{pH}$ buffer.
This is valid for an ideal case, as side processes - especially for tap water - will ...
0
What I would do is I would compare their acid strengths. Due to inductive forces, deprotonating the 1,2-dihydropyrazine would result in a more stable compound than that in pyridine--the nearby nitrogen (electronegative) will share the burden of the negative charge. Therefore, 1,2-dihydropyrazine is more acidic and thus is less basic.
3
You may have confused barium peroxide with barium metal. The metal can indeed displace hydrogen from hypochlorous acid, not to mention (for a metal as reactive as barium) from the water in which the acid is dissolved; but metal peroxides will produce oxygen and water from the acid. So your missing product is water, not hydrogen.
Tricky half-reactions
If we ...
6
Your reasoning is correct. Perhaps the answer key is mistaken.
For part (a), in the reaction
$$\ce{NH3 + H2O <=> NH4+ + OH-}$$
water is donating a proton $(\ce{H+}$ ion) and hence is behaving as a Brønsted acid. Since all Brønsted acids are Lewis acids, water is behaving as a Lewis acid.
For part (d) as well, the half reactions are:
$$
\begin{align}
\...
1
In acid-base titrations, the pH at the equivalent point is usually taken as the average value of the last p$K\ce{_a}$ preceding the equivalence point and the pH of the final NaOH solution. Here the last $p$K$\ce{_a}$ value is $4.27$. The $\ce{NaOH}$ solution has a pH equal to $13$. Average value : $(13 + 4.27)/2 = 8.64$. It is nearly $8.40$ as proposed in ...
0
This is an interesting question and environmentally related significant topic.
First, a pertinent related observation on dissolved oxygen content, to quote a question and its answer, which I believe to be factually accurate:
How does salinity affect Dissolved Oxygen solubility?
Dissolved oxygen decreases exponentially as salt levels increase. That is why, ...
2
Per a source, to quote:
Here are the nine major acids in coffee, listed from highest concentration to lowest: chlorogenic, quinic, citric, acetic, lactic, malic, phosphoric, linoleic, and palmitic (3). The brewing process releases acids from coffee beans, giving this beverage a pH of 4.85 to 5.10, which is considered acidic.
As such, the action of Sodium ...
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