NESA Chemistry Analysis of Organic Substances

Bromine water is used to test for the presence of carbon-carbon double bonds (unsaturation). It would not react with either of these saturated alcohols.

Potassium nitrate is generally unreactive with alcohols and would not produce a visible change to help distinguish between the two substances.

Sodium carbonate is typically used to test for acidic substances like carboxylic acids by observing effervescence (carbon dioxide gas), but it does not react with alcohols.

Acidified potassium permanganate is a strong oxidizing agent. It will oxidize the primary alcohol (2-methylpropan-1-ol), changing color from purple to colorless, but will not react with the tertiary alcohol (2-methylpropan-2-ol).

This is a solution of Iron(III) nitrate. Neither $Fe^{3+}$ nor $NO_3^-$ ions react with bromine water, so the solution would not be decolourised.

Chloride ions ($Cl^-$) cannot reduce bromine ($Br_2$) because chlorine is a stronger oxidising agent than bromine. Therefore, no reaction occurs to remove the bromine colour.

Pentanal (C₅H₁₀O) can cause a colour change with bromine because it is an aldehyde. Aldehydes are easily oxidised to carboxylic acids, and in this reaction, bromine (Br₂), which is orange-brown, is reduced to colourless bromide ions (Br⁻). As a result, the orange colour of bromine water disappears when it reacts with pentanal.

The condensed formula represents 2-pentene, which contains a carbon-carbon double bond ($C=C$). Alkenes undergo a rapid addition reaction with bromine water, consuming the $Br_2$ and turning the orange solution colourless.

Dichromate is a strong oxidizing agent used to test for primary and secondary alcohols or aldehydes, but carboxylic acids are already fully oxidized at the carbon atom and will not react.

Bromine water is used to test for unsaturation (such as alkenes and alkynes) or highly activated aromatic rings, not carboxylic acids.

Sodium sulfate is a neutral salt and does not undergo an acid-base reaction with weak acids like carboxylic acids.

Sodium carbonate is a weak base that reacts with carboxylic acids to produce carbon dioxide gas. The visible effervescence (bubbling) serves as a positive test for the presence of an acid.

Amines are basic compounds and do not react with sodium hydrogen carbonate to produce carbon dioxide.

Haloalkanes do not have acidic properties sufficient to react with sodium hydrogen carbonate to release carbon dioxide.

Carboxylic acids are stronger acids than carbonic acid, so they react with sodium hydrogen carbonate ($NaHCO_3$) to release carbon dioxide gas ($CO_2$).

Alcohols are weaker acids than carbonic acid and do not react with sodium hydrogen carbonate to evolve carbon dioxide.