With that out of the way, let's get started.
Factor #1 - Charge.
Removal of a proton, H+ , decreases the formal charge on an atom or molecule by one unit. This is, of course, easiest to do when an atom bears a charge of +1 in the first place, and becomes progressively more difficult as the overall charge becomes negative. The acidity trends reflect this:
Note that once a conjugate base (B-) is negative, a second deprotonation will make the dianion (B 2-). While far from impossible, forming the dianion can be difficult due to the buildup of negative charge and the corresponding electronic repulsions that result.
Factor #2 - The Role of the Atom
This point causes a lot of confusion due to the presence of two seemingly conflicting trends.
Here's the first point: acidity increases as we go acrossa row in the Periodic Table. This makes sense, right? It makes sense that HF is more electronegative than H2O, NH3, and CH4 due to the greater electronegativity of fluorine versus oxygen, nitrogen, and carbon. A fluorine bearing a negative charge is a happy fluorine.
But here's the seemingly strange thing. HF itself is not a "strong" acid, at least not in the sense that it ionizes completely in water. HF is a weaker acid than HCl, HBr, and HI. What's going on here?
You could make two arguments for why this is. The first reason has to do with the shorter (and stronger) H-F bond as compared to the larger hydrogen halides. The second has to do with thestability of the conjugate base. The fluoride anion, F(-) is a tiny and vicious little beast, with the smallest ionic radius of any other ion bearing a single negative charge. Its charge is therefore spread over a smaller volume than those of the larger halides, which is energetically unfavorable: for one thing, F(-) begs for solvation, which will lead to a lower entropy term in the ΔG.
Note that this trend also holds for H2O and H2S, with H2S being about 10 million times more acidic.
Factor #3 - Resonance.
A huge stabilizing factor for a conjugate base is if the negative charge can be delocalized through resonance. The classic examples are with phenol (C6H5OH) which is about a million times more acidic than water, and with acetic acid (pKa of ~5).
Watch out though - it isn't enough for a π system to simply be adjacent to a proton - the electrons of the conjugate base have to be in an orbital which allows for effective overlap (for a dastardly trick question in this vein that routinely stymies Harvard premeds, look here.)
Factor #4 - Inductive effects. Electronegative atoms can draw negative charge toward themselves, which can lead to considerable stabilization of conjugate bases. Check out these examples:
Predictably, this effect is going to be related to two major factors: 1) the electronegativity of the element (the more electronegative, the more acidic) and the distance between the electronegative element and the negative charge.
Factor #5 - Orbitals. Again, the acidity relates nicely to the stability of the conjugate base. And the stability of the conjugate base depends on how well it can accomodate its newfound pair of electrons. In an effect akin to electronegativity, the more s character in the orbital, the closer the electrons will be to the nucleus, and the lower in energy (= stable! ) they will be.
Look at the difference between the pKa of acetylene and alkanes - 25! That's 10 to the power of 25, as in, "100 times bigger than Avogadro's number". Just to give you an idea of scale. That's the amazing thing about chemistry - the sheer range in the power of different phenomena is awe-inspiring.
There's actually a mnemonic I've found that can help you remember these effects. I can't take credit for it, but here it is:
Charge
Atom
Resonance
Dipole Induction
Orbitals
= CARDIO.
Wiki User
∙ 11y agoAcidity in organic compounds typically arises from the presence of a hydrogen ion that can be donated to another molecule. Organic bases, on the other hand, can accept a proton. The degree of acidity or basicity is determined by factors such as the stability of the resulting ions and the structure of the molecule.
Wiki User
∙ 13y agoThere is not necessarily any difference when considering individual compounds: Tetramethyl ammonium hydroxide is as strongly alkaline as most inorganic alkalies. As a generalization, however, most organic acids and bases are weaker than strong inorganic alkalies and acids. However, many inorganic ones are also weak: The third ionization constant of phosphoric acid is smaller than for acetic or formic acid.
No, pH is not a temperature. pH is a measure of the acidity or basicity of a solution, while temperature is a measure of the average kinetic energy of particles in a substance. They are two different properties that can be measured independently.
Not necessarily. Organic compounds are simply compounds that contain carbon, and many organic compounds are essential for the body to function properly. However, some synthetic organic compounds, such as certain pesticides or chemicals, can be harmful to health if consumed in large amounts. It is important to be mindful of the source and type of organic compounds you come into contact with.
No, elements are not always part of an organic compound. Elements can exist in various forms and compounds, both organic and inorganic. Organic compounds are defined by the presence of carbon atoms bonded to hydrogen atoms, but elements themselves are not restricted to being part of organic compounds.
Basically, organic compounds have carbon. Inorganic do not (though there are some exceptions)
Organic compounds. Organic compounds are molecules that contain carbon, often combined with other elements like hydrogen, oxygen, nitrogen, sulfur, and phosphorus. They are essential for life and form the basis of many biological processes.
HCl is an acid, so it does not possess basicity but rather acidity. Its basicity is 0.
No, solid compounds do not have a pH. pH is a measure of the acidity or basicity of a solution, not a solid compound. The pH of a solution can be affected by the solid compound dissolving in the solution.
pH is a scale used to measure acidity or basicity.
acidity or basicity of a solution
the aidity of a compound is the acidity of a coumpound get it? if you still cannot get go back to general chemistry instead of organic chemistry i hope that this helps you
The acidity or basicity are expressed by pH (the negative logarithm of the activity of hydronium ion).
Protons are important in organic chemistry because they determine the acidity and basicity of molecules. Protons are involved in acid-base reactions, catalysis, and the stabilization of molecular structures through hydrogen bonding. Additionally, the transfer of protons plays a key role in many organic reactions and mechanisms.
Chemists use the pH scale to express the degree of acidity or basicity of a substance. The pH scale ranges from 0 to 14, with values below 7 indicating acidity, 7 being neutral, and values above 7 indicating basicity. pH is a logarithmic scale, so each whole number change represents a tenfold difference in the acidity or basicity of the substance.
The pH is a measure of the acidity/basicity of a solution.
pH
The acidity or basicity of a compound is determined by its ability to donate or accept protons (H+ ions). Compounds that release protons in solution are considered acidic, while those that accept protons are considered basic. The pH scale can be used to quantitatively measure the acidity or basicity of a compound, with values below 7 indicating acidity and values above 7 indicating basicity.
Henry Hing-Lai Wai has written: 'Acidity functions and the protonation behaviour of organic bases in perchloric acid' -- subject(s): Basicity, Acids, Perchloric acid, Acidity function