Question

a water soluble compound turns red litmus blue

3.SIThe following observations are frequently made in the lab. In each case below Istate in brief terms, the deduction or deductions which may be made. Las to the nature of the compound under study? a) water solable compound tumsa I red litmus to blue b.) when a small piece of sodium metal. was place in a test tube containing Talla uid unknown, a small stream Of bubble was Bbserved, TC.) an unknown liquid compound tumed a dark reddish Jones Reagent green. Ideen unknown livid compound was shaken with Tollens reagent in small test twbe. A mindrom le. an unknown compound decoloured Ta solution of bromine and methylene chloride

Answer 1

a) red litmus paper turns blue under basic or alkaline conditions. (OH^- ions present)

alkaline solution 25

b) dilute acids or acidic hydrogen containing compounds or even water can also reacts with sodium and produces hydrogen gas as bubbles

2H⁺ + 2Na ==> H₂ (g) + 2Na⁺

Bubbles of hydrogen gas - Sodium Metal nun + Acid solution

c) reddish to green means the unknown could be any of the primary alcohol, secondary alcohol, and aldehyde. Jones reagent oxidizes these to finally carboxylic acids.

Jones R-CH,OH + Cr3+ reddish OH 1° ROH green OH Jones + Cr3+ reddish RR RR 2° ROH green Jones + Cr3+ RH reddish ROH. Aldehyde green

d) only aldehydes and methyl ketones will give a silver mirror test with ammonical silver nitrate solution (Tollen's reagent)

e) alkenes decolorizes bromine solution and forms dibromide compound.

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