Give chemical tests to distinguish between the following pairs of compounds :
Propanal and propanone.

Explanation

i. `MeCH_(2)CHO` (Propanal) (I) and `MeCOMe` (Propanone) (II).
a. Both give 2,4-DNP test.
b. (II) gives positive iodoform test, whereas (I) does not.

ii. Acetophenone `(PhCOMe)` (I) and benzophenone `(PhCOPh)` (II).
a. (I) gives positive iodoform test, (II) does not.
iii. Phenol `(PhOH)` (I) and benoic acid `(PhCOOH)` (II).
a. (II) gives effervescenes of `CO_(2)` with `NaHCO_(3)`, (I) does not.
`PhCOOH+NaHCO_(3)rarr PhCOONa+CO_(2)+H_(2)O`
`PhOH+NaHCO_(3)rarr` No evolution of `CO_(2)`
b. Phenol gives violet colour with netural `FeCl_(3)` solution but (II) gives buff coloured precipitate.
`3PhOH+FeCI_(3)rarr underset("Ferric phenoxide (Violet colour)")((PhO)_(3)Fe+3HCl)`
`3PhCOOH+FeCI_(3)rarr underset("Ferric benzoate (Buff ppt.)")((PhCOO)_(3)Fe+3HCl)`
iv. Benzoic acid `(PhCOOH)` (I) and ethyl benzoate `(PhCOOEt)` (II).
a. (I) gives `NaHCO_(3)` test [as in (iii)], but (II) doesnot.
b. (II) on boiling with excess of `NaOH` gives ethyl alcohol and sodium benzoate. Ethyl alcohol gives positive iodoform test.
`PhCOOEt+NaOH overset(Delta)rarr PhCOONa+C_(2)H_(5)OH`
`PhCOOEt+NaOH overset(Delta)rarr PhCOONa+C_(2)H_(5)OH`.

v. Penthan-2-one (I) and pentan-3-one

a. (I) gives positive Iodoform test `[(MeCO-)` group], but (II) does not.

b. (I) being a methyl ketone gives white ppt. with `NaHSO_(3)`, but (II) does not.

vi. Benzaldehyde `(PhCHO)` (I) and acetopenone `(PhCOMe)` (II).
a. (I) gives positive Tollens test, but (II) does not.
b. (II) gives positive Iodoform test `[(MeCO-)` group], but (I) does not.
`PhCHO+[Ag(NH_(3))_(2)]^(o+)OH^(Θ)rarr PhCOO^(Θ)+Ag darr`
`PhCO vdots Me underset(NaOI)rarr PhCOONa+underset("Yellow ppt.")CHI_(3)`
vii. Ethanal `(MeCHO)` (I) and propanal `(MeCH_(2)CHO)` (II).
a. (I) gives positive Iodoform test, but (II) does not.
`Me vdots CHO overset(NaOH)rarr HCOONa+CHI_(3)`