<span>1)
Calculate [H+] from the pH:
pH = log { 1 / [H+] } = - log [H+]
=> [H+] = 10 ^ (-pH)
=> [H+] = 10 ^ (-2.80) = 0.00158
2) Assume the stoichiometry 1:1
=> HA aq ---> H(+) aq+ A(-) aq
=> [A-] = [H+] = 0.00158
[HA] = 0.294 – 0.00158 = 0.29242
3) Calculate Ka</span>
<span>Ka = [H+] *[A-] / [HA] = (0.00158)*(0.00158) / 0.29242 =8.54 * 10^ -6
Answer: 8.5 * 10^ -6</span>
Answer:
A non-polar liquid.
Explanation:
Whether a substance dissolves quickly or not depends on how strongly the molecules (or atoms of an element) of a substance are attracted to one another. These interactions between atoms and/or molecules are called intermolecular forces, or IMFs for short. There are several different ones, and these are distinguished from <em>intra</em>molecular forces which are the bonds holding atoms in the molecule together. Attached is a nice little summary of these forces to consider. Our decision lies within the fact that we must pick the substance that experiences the strongest IMF (the one with the most energy). As it turns out, a dipole in a molecule confers some charge distribution on the molecule which makes slightly positive and negative ends. These can attract each other, and it's called dipole-dipole interactions. It can technically happen in a mixture, but let's assume we're dealing with pure substances. Dipoles can only form in polar compounds however, so a non-polar liquid (which is composed of non-polar molecules), will lack these dipoles and therefore cannot form dipole-dipole interactions between the molecules. This results in only having something called dispersion forces (which really every molecule attraction has - so this is the only one). It is very weak, and since the attraction between these molecules is weak, they will tend to come apart, and evaporate. You can think of the IMFs like glue, and a weak glue will not hold the molecules together well, and they will evaporate away.
On the other hand, polar (from dipole interactions) compounds can have general dipole-dipole interactions or hydrogen-bonding interactions (which is a special type of dipole-dipole interaction). H-bonding requires a Hydrogen bonded to either a Nitrogen, Oxygen, or Fluorine to do this. The main thing, is the non-polar ones don't have a dipole, and so they can't form a good intermolecular bond and evaporate quickly.
Water can H-bond, which is why it takes so long to dry and for it to evaporate in general. Nail polish, which is really a solution of acetone, has considerably weaker dipole-dipole bonds (compared to H-bonds), and evaporates quicker than water. Hope this helps!
Note: Figure taken from Chemistry: The Molecular Nature of Matter and Change 8th edition.
CH3CH2CH2CH3 < CH3CH2CHO < CH3CHOHCH3
Explanation:
Boiling point trend of Butane, Propan-1-ol and Propanal.
Butane is a member of the CnH2n+2 homologous series is an alkane. Alkanes have C-H and C-C bonds which have Van der waals dispersion forces which are temporary dipole-dipole forces (forces caused by the electron movement in a corner of the atom). This bond is weak but increases as the carbon chain/molecule increases.
In Propan-1-ol(Primaryalcohol), there is a hydrogen bond present in the -OH group. Hydrogen bond is caused by the attraction of hydrogen to a highly electronegative element like Cl-, O- etc. This bond is stronger than dispersion forces because of the relative energy required to break the hydrogen bond. Alcohols (CnH2n+1OH) also experience van der waals dispersion forces on its C-C chain and C-H so as the Carbon chain increases the boiling point increases in the homologous series.
Propanal which is an Aldehyde (Alkanal) with the general formula CnH2n+1CHO. This molecule has a C-O, C-C and C-H bonds only. If you notice, the Oxygen is not bonded to the Hydrogen so there is no hydrogen bond but the C-O bond has a permanent dipole-dipole force caused by the electronegativity of oxygen which is bonded to carbon. It also has van der waals dispersion forces caused by the C-C and C-H as the carbon chain increases down the homologous series. The permanent dipole-dipole forces are not as easy to break as van der waals forces.
In conclusion, the hydrogen bonds present in alcohols are stronger than the permanent dipole-dipole bonds in the aldehyde and the van der waals forces in alkanes (irrespective of the carbon chain in Butane). So Butane < Propanal < Propan-1-ol
The subatomic particle that makes the atoms of each element different are the protons. The specific number of protons for a particular element distinguishes one element to another.
The far more common hydrogen isotope, protium, has NO neutrons in the nucleus.