Why is sh more acidic than oh

If you struggled with this part of the question, first draw the compounds whose names were provided, then think about the types of reactions e.

The thiol pKa is about 10 and the pKa for water to hydroxide is about 16 so we should use bases that can deprotonate the thiol.

This means selecting the conjugate base of an acid whose pKa is greater than Carbanions such as CH3- are certainly strong enough. Draw the structures and compare to the scheme Why is hydroxide a poor choice? This means that there are two possible nucleophiles now if the reaction, the alkoxide, RO- and the hydroxide, HO-.

The reaction of these two nucleophiles with the bromobutane will compete to give two different products and lower the yield of the desired ether product. The NH2 would hold the basic electrons tighter due to Nitrogen being more electronegative, but it turns out the tight bonding … But rather than looking at electronegativity which refers to electrons in a bond , ionize your species and examine the leaving group.

For each pair, circle the more acidic compound. Compare Products: Select up to 4 products. Note that S and O are in the same group of the periodic table. Which one is more acidic? Dihydrogen borate ion. Hydrogen phosphate ion.

This is because a negative charged O Oxygen anion is more stable than a N anion. And there are two lone pairs of electrons present on the N atom which strongly repel the bond pairs. In general, comparing basicity within the same column, you take size into consideration. Because SH- is more stable than OH-, the hydroxide will want to pick up a proton and become neutral and it will be more basic. HS-S 2-Sulfide ion. It increases acidity. This explains why we have this periodic trend.

The repulsion of lone pairs of electrons is more than bond pairs. Tiffany Trump announces engagement with WH photo Hydrogen carbonate ion. NH3 is a weak base with pH 11 at standard conditions but it is also considered amphoteric which means it can act as both acid and base under different conditions.

Are you referring to carboxylic acid derivatives or free NH3 and OH- in solution? Thus, since the odds of more basic element are greater for negatively charged molecules nh2- than for neutral molecules nh3 , nh2- is definitly more basic than nh3. We know that halogens tend to be pretty stable as anions, for the most part, so their anionic form may be more stable than their neutral form.

Use resonance structures to account for the acidity of acetonitrile. Any factor that stabilises the anion more than it stabilises the acid should increase the acidity. It decreases electron density on benzene ring and delocalizes negative charge of phenoxide ion.

Alcohols are slightly less acidic than water, due to the poor electronegativity of carbon, but chloral hydrate, Cl 3 CCH OH 2, and 2,2,2,-trifluoroethanol are significantly more acidic than water, due to inductive electron withdrawal by the electronegative halogens and the second oxygen in chloral hydrate.

For each pair of compounds below, identify the more acidic compound. When moving vertically within a given group on the periodic table, the trend is that acidity increases from top to bottom. This can be illustrated with the haloacids HX and halides as shown below: the acidity of HX increases from top to bottom, and the basicity of the conjugate bases X — decreases from top to bottom. The acidity of the H in thiol SH group is also stronger than the corresponding alcohol OH group, following the same trend.

In order to make sense of this trend, we will once again consider the stability of the conjugate bases. When moving vertically in the same group of the periodic table, the size of the atom overrides its electronegativity with regards to basicity.

The atomic radius of iodine is approximately twice that of fluorine, so in an iodide ion, the negative charge is spread out over a significantly larger volume, so I — is more stable and less basic, making HI more acidic. For elements in the same group, the larger the size of the atom, the stronger the acid is; the acidity increases from top to bottom along the group. The resonance effect accounts for the acidity difference between ethanol and acetic acid.

For both ethanol and acetic acid, the hydrogen is bonded with the oxygen atom, so there is no element effect that matters. However, the p K a values and the acidity of ethanol and acetic acid are very different.

What makes a carboxylic acid so much more acidic than an alcohol? As stated before, we begin by considering the stability of the conjugate bases, remembering that a more stable weaker conjugate base corresponds to a stronger acid. For acetate, the conjugate base of acetic acid, two resonance contributors can be drawn and therefore the negative charge can be delocalized shared over two oxygen atoms. However, no other resonance contributor is available in the ethoxide ion, the conjugate base of ethanol, so the negative charge is localized on the oxygen atom.

Once it is formed, it is very reactive. SH- is also very reactive, but it want to form less because it is a less stable molecule. Acids and their conjugate based, and bases and their conjugate acids have to be looked at together. And many times, the stability or lack of relatively of the other form you are looking at is the important part.

Remember, these are all equilibrium, even OH- H2O is in equilibrium, despite the fact that you can get a strong base in the form of NaOH. I understand what you are saying, that weak acids are conjugate to strong bases, and vice-versa. Yet I am still having trouble reconciling what I know of oxygen with the basicity of the hydroxide anion.

I still cannot grasp how an atom as electronegative as oxygen, which therefore holds its electrons very tightly, can so easily donate them in order to abstract a proton. My confusion is further compounded by the fact that oxygen is a period 2 element.