A tarnished copper vessel begins to shine again when rubbed with lemon . justify the statement

Open in App

Solution

Copper vessel is tarnished due to copper oxide layer formed on its surface .
Copper oxide is basic in nature. The green coating on copper vessels is due to the formation of basic copper carbonate formed by the attack of O2, CO2 and moisture of the air on the copper vessel.
Lemon is acidic. Thus, on rubbing the tarnished copper vessel with lemon, the basic copper oxide or copper carbonate reacts with the acid (citric acid) present in the lemon to form a salt which is washed away with water.
copper+air--->basic copper carbonate

Suggest Corrections

Similar questions

Q. Assertion :Tarnished copper utensils are cleaned with lime juice or tamarind. Reason: When these tarnished vessels are rubbed with lime juice or tamarind the weak acids present in them dissolve the green copper carbonate and original shine returns.

Q. Assertion :You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Reason: Copper reacts with moist carbon dioxide in air to form copper carbonate and as a result, copper vessel loses its shiny brown surface forming a green layer of copper carbonate. Tarnished copper vessels are cleaned with lemon or tamarind juice to give the surface of the copper vessel its charateristic lustre.

A silver article generally turns black when kept in the open for a few days. The article when rubbed with toothpaste again starts shining.
The phenomenon due to which silver articles turn black is called ___.

A silver article generally turns black when kept in the open for a few days. The article when rubbed with toothpaste again starts shining. Name the black substance formed and give its chemical formula :

Give reason

1. Aluminum is more reactive than iron yet there is less corrosion of aluminum as compared to iron when both are exposed to air.

2. Tarnished copper vessels are cleaned with tamrind juice.

Join BYJU'S Learning Program