Saved Bookmarks
| 1. |
Arrange the following compounds in the decreasing of their boiling points and solubilitiy in H_(2)O. a.(I) Methanol(II) Ethanol(III) Propan-1-ol(IV) Butan-1-oI(V) Butan-2-oI(VI) Pentane-1-oI b. (I) Pentanol(II) n-Butane(III) Pentanal(IV) Ethoxy ethane c. (I) Pentane(II) Pentane-1,2,3,-triol(III) Butanol d. (I) Butane(II)Butanol(III) Pentanol e. (I) Pentan-1-oI(II)2-Methyl butan-2-oI(III)3-Methyl butan-2-oI f.(I) n-Butyl alcohol(II) sec-Butyl alcohol(III)t-Butyl alcohol |
|
Answer» Solution :a.Boiling point order:`VI gt IV gt V gt III gt II gt I` Solubility order:`I gt II gt III gt V gt IV gt VI` Explanation:All of them are alcohols, so all have H-bonding. As the molecular mass and surface area increase, the boiling point increase and solubility decreases.Out of (IV) and (V) , there is branching in (V) and has less surface area than (IV), so the boiling of (IV) gt (V), but solubility of (V) gt (IV). b.Boiling point order: `I gt III gt IV gt II Solubility order:`I gt III gt IV gt II` In (I), there is H-bonding, in (II) (aldehyde), dipoledipole INTERACTION, in (III) (ether), slightly polar due to EN of O, and in (IV) (alkane), van der Waals interaction (non-polar). c.Boiling point order:`II gt III gt I` Solubility order:`II gt III gt I` In (II), three `(---OH)` GROUND, more H-bonding, in (II), one Waals interaction. d.Boiling point order:`III gt II gt I` Solubility order:`II gt III gt I` Both (II) and (III) have H-bonding, but molecular mass of (III) gt (II), hence the given boiling point order. Solubility of (II) gt (III), because in (III), size of R-group non-polar (hydrophobic part) is larger, hence the given solubility order. e.Boiling point order:`I gt II gt III` Solubility order :`III gt II gt I` (I)  (II) (III)  All alcohols have H-bonding, same molecular MASSES, but branching increases form(I) to (II). Their shape becomes more compact and spherical and therefore less surface contact is available for van der Waals attractive FORCE. So, boiling point decreases and solubility in `H_(2)O` increase. f.Boiling point order :`I gt II gt III` Solubility order :`III gt II gt I` All aclcohols have H-bonding. Surface area of `(I) gt (II) gt III` . Hence, the boiling point and solubility order are as given above. |
|