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प्रश्न
Define corrosion.
Define the following term:
Corrosion
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उत्तर १
When a metal is attacked by substances around it, such as moisture, acids, etc., it is said to corrode, and this process is called corrosion.
उत्तर २
Corrosion is an electrochemical process in which a metal is oxidised to a metal oxide or another salt of the metal by losing electrons to oxygen or another electronegative element, forming a coating on the metal surface.
संबंधित प्रश्न
Corrosion can be prevented by using ……………. solution.
The chemical formula for rust is.............. .
Why does the colour of copper sulphate solution change when an iron nail is dipped in it?
Identify in the following reaction (a) the substance oxidised, and (b) the substance reduced:
\[\ce{ZnO + C -> Zn + CO}\]
Is oxidation an exothermic or an endothermic reaction?
When a magnesium ribbon is heated, it burns in air to form magnesium oxide. Write a balanced chemical equation for this reaction. Name
- substance oxidised, and
- substance reduced.
Hydrogen burns with a ______ flame and ______ sound is heard.
Fill in the blank
In redox reaction oxidation and reduction occur ............................
Name the following:
The process in which oxygen is added or hydrogen is removed.
Give the general group study of hydrogen with reference to
reducing power
Why zinc and aluminium are considered to have a unique nature. Give balanced equations to support your answer.
State whether the following conversion is oxidation or reduction:
2Cl- - e-→ Cl2
Divide the following reactions into oxidation and reduction half-reaction:
Zn + Pb2+→ Pb + Zn 2+
Divide the following reactions into oxidation and reduction half-reaction:
Zn + Cu2+ → Cu + Zn 2+
Divide the above equation into oxidation and reduction half-reactions.
Name:
an oxidizing agent that does not contain oxygen.
Complete and balance the following equation:
H2 + S → ___________
Complete and balance the following equation:
Zn +_________________→ZnCl2 + H2
Explain the term redox reaction with an example involving the reaction of hydrogen sulphide with chlorine.
Identify the oxidising agent (oxidant) in the following reactions
`"Pb"_3"O"_4 + 8"HCl" -> 3"PbCl"_2 + "Cl"_2 + 4"H"_2"O"`
Identify the oxidising agent (oxidant) in the following reactions
`3"Fe" + 4"H"_2"O" -> "Fe"_3"O"_4 + 4"H"_2`
Which among the following are physical or chemical change?
Evaporation of petrol
Which among the following are physical or chemical change?
Heating of an iron rod to red hot
During the reaction of some metals with dilute hydrochloric acid, following observations are made.
Some bubbles of a gas are seen when lead (Pb) is reacted with the acid.
Explain this observation giving suitable reason.
On adding a drop of barium chloride solution to an aqueous solution of sodium sulphite, white precipitate is obtained :
- Write a balanced chemical equation for the reaction involved.
- What other name can be given to this precipitation reaction?
- On adding dilute hydrochloric acid to the reaction mixture, white precipitate disappears. Why?
The tarnishing of metals is an example of ______ reaction.
The sum of the oxidation number of all atoms in a compound is ______.
Identify the following reactions as oxidation/reduction/redox reaction
Zn + CuSO4 → Cu + ZnSO4
What is rancidity?
Define oxidation number.
Find the oxidation number of the element in the following compound.
Ca in CaH2
Find the oxidation number of the element in the following compound.
Mg in MgO
Find the oxidation number of the element in the following compound.
A1 in AlCl3
It is recommended to use air tight containers for storing oil for a long time.
A reddish brown metal used in electrical wires when powdered and heated strongly turns black. When hydrogen gas is passed over this black substance, it regains its original colour. Based on this information answer the following questions:
- Name the metal and the black substance formed.
- Write balanced chemical equations for the two reactions involved in the above information
The oxidizing agent in the equation \[\ce{S + 2H2SO4 -> 3SO2 + 2H2O}\] is ______.
