Advertisements
Advertisements
प्रश्न
Observe the following picture and answer the following questions:
- What is rust?
- Write the chemical formula of rust.
- Write the reaction of oxidation of iron at the anode.
- Write the reaction of oxidation of iron at the cathode.
- What is corrosion?
Advertisements
उत्तर
- Rust is a reddish-brown coloured hydrated ferric oxide layer deposited on the surface of iron objects that are exposed to moist air.
- Chemical formula of rust is Fe2O3.xH2O.
- Anode region: \[\ce{Fe_{(s)} -> Fe^{2+}_{ (aq)} + 2e^-}\]
- Cathode region: \[\ce{Fe^{2+}_{ (aq)} -> Fe^{3+}_{ (aq)} + e^-}\]
- Metals get attacked by substances around it such as moisture, acids, etc. Metal is said to ‘corrode’ due to this attack and the process is called corrosion.
APPEARS IN
संबंधित प्रश्न
Write two methods of preventing the rusting of iron.
Why do we apply paint on iron articles?
Which metals do not corrode easily?
Two methods by which rusting of iron can be prevented are ______ and ______.
Explain why Iron sheets are coated with zinc during galvanization.
The corrosion of iron is called ______.
______ and ______ are necessary for the rusting of iron.
With the help of labelled diagrams, describe an activity to find out the conditions under which iron rusts.
Name two metals which resist corrosion due to the formation of a thin, hard and impervious layer of oxide on their surface.
Name an alloy of copper. State its chemical composition and any one use.
Explain why, when a copper object remains in damp air for a considerable time, a green coating is formed on its surface. What is this process known as?
Explain why, the galvanised iron article is protected against rusting even if the zinc layer is broken.
Brass is an alloy of ______.
What is corrosion? What are necessary conditions for corrosion?
Corrosion can be an advantage in some case.Explain ?
Compare roasting and calcination.
Complete the process of iron rusting by filling the blanks. Suggest a way to prohibit the process.
The iron rust is formed due to........................... reaction. Different
regions on iron surface become anode and cathode.
Reaction on anode region :
`F_e(s) → Fe^(2+) (aq) +2e^-`
Reaction on anode region :
`O_2(g) + 4H^+(aq) +............................ → 2H_2 O (l) `
When Fe2+ ions migrate from anode region they react with ................... to form Fe3+ ions.
A reddish coloured hydrated oxide is formed from ............... ions. It is called rust.
`2Fe_(3+) (aq) + 4H_2O(l) → ................. + 6H_+(aq) `
A way to prevent rusting ..................................................................
Write three methods of preventing rusting of iron.
What is ‘rusting’?
Give reason.
An iron article should be given a coat of paint
Give reason.
Copper and brass utensils should be tinned.
Give a reason why rust turns moist red litmus blue.
Write a short note on Alloying.
Rusting of iron : Fe2O3 : : corrosion of copper : ______
Find the odd one out and give its explanation.
Find the odd one out and give its explanation.
Write scientific reason.
Anodization method is useful for prevention of the corrosion of the aluminium.
Write scientific reason.
On exposure to air, silver articles turn blackish after some time.
Complete flow chart given below.
What is rust?
Galvanisation is a method of protecting iron from rusting by coating it with a thin layer of ____________.
The diagram shows the reaction between metal and dil. acid.
What is the reason for different behaviour of Mg in test tube B?
Identify the correct statement from the following:
Generally, when metals are treated with mineral acids, hydrogen gas is liberated but when metals (except Mn and Mg), treated with HNO3, hydrogen is not liberated, why?
Galvanisation is a process used to prevent the rusting of which of the following?
In ______ process a layer of molten tin is deposited on metals.
Describe two changes that are harmful. Explain why you consider them harmful. How can you prevent them?
