Contents
What is the pKa of phenol?
The pKa value for phenol is 10.0, and two series of substituted phenols are given: 2-fluorophenol, 3-fluorophenol, and 4-fluorophenol have pKa values of 8.7, 9.3, and 9.9, respectively; 2-nitrophenol, 3-nitrophenol, and 4-nitrophenol have pKa values of 7.2, 8.4, and 7.2, respectively.
Which phenol has lowest pKa?
The phenol derivative picric acid has a pKa of 0.25, lower than that of trifluoroacetic acid. Use a resonance argument to explain why picric acid has such a low pKa.
Which has highest value of pKa phenol?
Out of these phenols are more acidic than phenols. So, they will be least acidic and thus will have the highest pKa value. So, the correct answer is “Option D”.
Why is the pKa of phenol 10?
As phenol is more acidic, this means that its conjugate anion is more stable. Even though phenol is 106 more acidic than water, its pKa of 10 tells you that the acidity constant is 10-10 or that only one part in 1010 is ionized, the rest exists as phenol with H attached to oxygen.
What is the pH of phenol?
around 5 – 6
Properties of phenol as an acid The pH of a typical dilute solution of phenol in water is likely to be around 5 – 6 (depending on its concentration). That means that a very dilute solution isn’t really acidic enough to turn litmus paper fully red. Litmus paper is blue at pH 8 and red at pH 5.
What is the pKa value?
In simple terms, pKa is a number that shows how weak or strong an acid is. A strong acid will have a pKa of less than zero. More precisely – pKa is the negative log base ten of the Ka value (acid dissociation constant). The lower the value of pKa, the stronger the acid and the greater its ability to donate its protons.
Which has lowest pKa value?
Since ClCH2COOH has only one α−Cl atom and Cl2CHCOOH has two α−Cl atoms; therefore, CHCl2COOH is a strongest acid among all and has lowest pKa value.
What is the pKa of HBr?
-8.7
Hydrobromic acid (HBr): pKa = -8.7.
Why does phenol have a low pKa?
In phenol, the lone pair of oxygen participates into resonance with the benzene ring. As a result, oxygen acquires a partial positive charge. The electron density of O—H bond then shifts towards oxygen decreases around H-atom. Hence, phenol is more acidic than ethanol and has lower pKa value than ethanol.
What is the pKa of pure water at 25 C?
15.7
In most general chemistry textbooks, the pKa of water at 25 ºC is listed as 14.0. In many organic chemistry textbooks and some biochemistry texts, however, the pKa of water at 25ºC is listed as 15.7.
Why does phenol have a low pH?
Phenol is a very weak acid and the position of equilibrium lies well to the left. Phenol can lose a hydrogen ion because the phenoxide ion formed is stabilised to some extent. The negative charge on the oxygen atom is delocalised around the ring. That is why phenol is only a very weak acid.
What is the pKa of phenol red?
Acid-Base Indicators
| Indicator | pH Range | pKa |
|---|---|---|
| Phenol red | 6.4 to 8.0 | 7.9 |
| Thymol blue | 8.0 to 9.6 | 8.9 |
| Phenolphthalein | 8.0 to 10.0 | 9.4 |
| Alizarin yellow R | 10.0 to 12.0 | 11.2 |
What is the formula for an alkanol phenol?
Alkanol: An alcohol where the hydroxyl group is bound to an alkyl group, with the general formula CnH2n+1OH. Phenol: An alcohol where the hydroxyl group is bound to a phenyl group, with the formula C6H5OH. Phenols: A group of compounds consisting of a phenol molecule with one or more substiuents.
What is the pKa value of phenazine?
pKa Values INDEX Inorganic 2 Phenazine 24 Phosphates 3 Pyridine 25 Carboxylic acids 4, 8 Pyrazine 26 HCO3 10.33* HSe– 11.00* 77 H2CrO4 -0.98 30 H 2S 7.00* 77
What are the values of the functional group pKa?
Approximate pKa chart of the functional groups: values to know 1. Protonated carbonyl pKa = ‐7 Other important pKa’s 2. Protonated alcohol or ether pKa = ‐2 to ‐3 H2 = 35 3. Carboxylic acid pKa = 4‐5 4. Ammonium ion pKa = 9‐10 5. Phenol pKa = 10 6.
How is phenol used in the production of nylon?
Phenol is used primarily in the production of phenolic resins and in the manufacture of nylon and other synthetic fibers. It is also used in slimicides (chemicals that kill bacteria and fungi in slimes), as a disinfectant and antiseptic, and in medicinal preparations such as mouthwash and sore throat lozenges.