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Question
Identify from the reaction the reactants that undergo oxidation and reduction.
\[\ce{NiO + H2 -> Ni + H2O}\]
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Solution
In a reaction, nickel oxide is changing to nickel. That is, oxygen is being removed from nickel oxide. Removal of oxygen from a substance is called reduction, so nickel oxide undergoes reduction.
In a reaction, hydrogen is changing to H2O. That is, oxygen is being added to hydrogen. Addition of oxygen to a substance is called oxidation, so hydrogen undergoes oxidation.
The reactions in which oxidation and reduction take place simultaneously are called Redox reactions.
RELATED QUESTIONS
Define ‘redox reaction’. Give one example.
Why does the colour of copper sulphate solution change when an iron nail is dipped in it?
Which of the statements about the reaction below are incorrect?
\[\ce{2PbO(s) + C(s) → 2Pb(s) + CO2(g)}\]
- Lead is getting reduced.
- Carbon dioxide is getting oxidised.
- Carbon is getting oxidised.
- Lead oxide is getting reduced.
Fill in the following blanks with suitable words:
The addition of hydrogen to a substance is called ........ whereas removal of hydrogen is called .......
When a magnesium ribbon burns in air with a dazzling flame and forms a white ash, is magnesium oxidised or reduced? Why?
Explain reduction in terms of gain or loss of oxygen with one example.
When copper powder is heated strongly in air, it forms copper oxide. Write a balanced chemical equation for this reaction. Name (i) substance oxidised, and (ii) substance reduced.
Define oxidation in terms of gain or loss of hydrogen with one example.
When a magnesium ribbon is heated, it burns in air to form magnesium oxide. Write a balanced chemical equation for this reaction. Name (i) substance oxidised, and (ii) substance reduced.
In the reaction represented by the following equation:
CuO (s) + H2 (g) → Cu (s) + H2O (1)
(a) name the substance oxidised
(b) name the substance reduced
(c) name the oxidising agent
(d) name the reducing agent
The process of respiration is:
(a) an oxidation reaction which is endothermic
(b) a reduction reaction which is exothermic
(c) a combination reaction which is endothermic
(d) an oxidation reaction which is exothermic
Name the following:
The process in which oxygen is added or hydrogen is removed.
Define redox reaction.
MULTIPLE CHOICE QUESTIONS
The process of adding oxygen to a substance is called
- oxidation.
- reduction.
- displacement.
- hydrogenation.
TRUE \ FALSE
Hydrogen is a good oxidizing agent.
The electron releasing tendency of zinc is ______ than that of copper.
Identify from the reaction the reactants that undergo oxidation and reduction.
Fe + S → FeS
Compare hydrogen with alkali metals on the basis of:
Oxide formation
Give the general group study of hydrogen with reference to
burning
Why zinc and aluminium are considered to have a unique nature. Give balanced equations to support your answer.
State, giving reason, whether the substances printed in bold letters have been oxidized or reduced.
Mg + 2HCl → MgCl2 + H2
Divide the above equation into oxidation and reduction half-reactions.
Which of the following statements about hydrogen is incorrect?
For the reaction PbO + H2→ Pb + H2O, which of the following statements is wrong?
Name:
a substance that oxidizes concentrated HCl to chlorine.
Name:
a substance that will reduce aqueous Iron(III)ions to iron(II)ions.
Name:
a gas that is oxidizing as well as a reducing agent.
Complete and balance the following equation:
H2 + S → ___________
Complete and balance the following equation:
CuO +__________→ Cu +___________
Explain the term reduction in term of addition and removal of oxygen/hydrogen with a suitable example.
State what is oxidising agent. Give an example of oxidising agent in the gaseous, liquid, and solid form.
When the positive charge on an ion increases or the negative charge on them decreases it is called as _______.
Explain the following reaction with their balanced chemical equation.
Hydrogen sulphide reacts with sulphur dioxide.
\[\ce{MnO2 + 4HCl -> + 2H2O + Cl2}\]
Identify the substance oxidized in the above equation.
Select the oxidising agent for the following reaction:
\[\ce{H2S + I2 -> 2HI + S}\]
Identify the reducing agent in the following reactions -
`"H"_2"O" + "F"_2 -> "HF" + "HOF"`
Identify the oxidising agent (oxidant) in the following reactions
`"V"_2"O"_5 + 5"Ca" -> 2"V" + 5"CaO"`
During the reaction of some metals with dilute hydrochloric acid, following observations are made.
The reaction of sodium metal is found to be highly explosive
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?
Write a short note on oxidizing and reducing agents.
Mention some oxidation reactions that occur in daily life.
The tendency of atoms to have eight electrons in the outer shell is known as ______.
Oxidizing agents are otherwise called ______.
Identify the following reactions as oxidation/reduction/redox reaction
2Mg +O2 → 2MgO
What are reducing agents? Give examples.
What are redox reactions? Give examples.
Define oxidation number.
Identify the type of chemical reaction given below:
\[\ce{2Mg + O2 -> 2MgO}\]
Answer the questions based on the equation below:
\[\ce{CH3 - CH2 - OH ->[{[O]}][K2Cr2O7/H2SO4] CH3 - COOH}\]
- What type of reaction is it?
- What is the role of the chemical written on the arrow?
- Give one example of one such type of chemical as in answer (b).
State whether the given chemical reaction is a redox reaction or not. Justify your answer.
\[\ce{MnO_2 + 4HCl->MnCl_2 +2H_2O + Cl_2}\]
Metals are good ______.
