All Questions
518
questions
125
votes
7
answers
87k
views
Is a negative pH level physically possible?
A friend of mine was looking over the definition of pH and was wondering if it is possible to have a negative pH. From the equation below, it certainly seems mathematically possible—if you have a $1.1$...
- 1,369
45
votes
4
answers
53k
views
The reason behind the steep rise in pH in the acid base titration curve
Most books refer to a steep rise in pH when a titration reaches the equivalence point. However, I do not understand why … I mean I am adding the same drops of acid to the alkali but just as I near the ...
- 2,423
32
votes
2
answers
35k
views
What is the pKa of the hydronium, or oxonium, ion (H3O+)?
Although the wikipedia page on Hydronium indicates a $\mathrm{p}K_\text{a}$ of −1.74, I noticed in the discussion of this page that the subject seems debated (cf. http://en.wikipedia.org/wiki/Talk:...
- 597
24
votes
2
answers
30k
views
Why are the majority of cleaning solutions basic?
When testing for pH for common household cleaning products, such as dishwasher fluid, I noticed that majority of them tend to be basic? Why is that? Do acid make good cleaning solutions as well?
- 341
21
votes
1
answer
4k
views
How can benzaldehyde have a pKa of 14.9?
There are numerous websites out there which claim that the pKa of benzaldehyde – C6H5CHO – is 14.90. (Just do a Google search for benzaldehyde pka to see what I ...
- 71.6k
21
votes
3
answers
17k
views
Does the number of H+ ions in solution go up on dilution of a weak acid?
In my textbook, a footnote says:
In case of weak acids, on dilution the total number of $\ce{H^{+}}$ ions in solution increases because dissociation of the weak acid increases
This didn't make ...
- 3,479
19
votes
1
answer
66k
views
How do I calculate the isoelectric point of amino acids, each of which has more than two values of pKa?
For most amino acids, the $\mathrm{pI}$ is simply the arithmetic mean of the amino and carboxyl $\mathrm pK_\mathrm a$s. However, for tyrosine and cysteine, which have more than one $\mathrm pK_\...
- 191
18
votes
4
answers
54k
views
How much can the pH change through dilution?
Consider an acidic solution with Hydrogen ion concentration, $\ce{[H+]}$ of $10^{-5}\:\mathrm{M}$. Since $\:\mathrm{pH} = -\log \ce{[H+]}$ the $\:\mathrm{pH}$ of solution is $5$. Suppose we dilute ...
- 299
17
votes
1
answer
17k
views
How does the litmus pH indicator work?
I'm wondering about how does the litmus solution work as a pH indicator.
And another question:
When you put drops of litmus solution into an colorless acid (e.g. $\ce{HCl}$), it turns red. But then ...
- 391
16
votes
1
answer
3k
views
Determining the pH of an organic solvent
Our work is faced with the issue of determining the charge of compounds that are dissolved in chloroform. One could realistically determine the charge of the relevant moieties knowing the $\mathrm{p}...
- 2,400
15
votes
1
answer
8k
views
Calculating the pH of a highly dilute solution of HCl
For relatively high concentrations of $\ce{HCl}$, I usually just assume that $[\ce{H+}] = [\ce{HCl}]$, because $\ce{HCl}$ is a strong acid and is completely ionized in solution. By taking the negative ...
- 1,128
15
votes
4
answers
71k
views
Shouldn't the pH at the equivalence point always be 7?
I learned in class that the equivalence point in an acid-base titration is reached when the solution contains an equal amount of substance of $\ce{OH-}$ and $\ce{H+}$ ions. However, in a weak acid and ...
- 2,423
15
votes
4
answers
21k
views
Is LiOH a weaker base than NaOH?
Is $\ce{LiOH}$ a weaker base than $\ce{NaOH}$?
Note: I'm not interested in "why," but rather what the "real" $\mathrm{p}K_
\mathrm{b}$ values are.
$$
\begin{array}{lcc}
\text{Data for Alkali Metal ...
- 22.3k
14
votes
5
answers
18k
views
Why isn't water acidic?
The definition of an acid is a compound with a hydrogen cation and a non-metal anion. Water is a hydroxide bonded to a hydrogen atom. This hydroxide has a net negative charge, too, since the negative ...
- 435
14
votes
2
answers
169k
views
What are the products of the dissociation of sodium bicarbonate in water? What is the relative pH of the solution?
I had a recent question on a test that asked what the products would be if sodium hydrogen carbonate were dissolved in water. I had a few candidate answers
$\displaystyle\ce{NaHCO3 -> Na+ + HCO3-}$...
- 371