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प्रश्न
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.
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उत्तर
Hydrogen gas is evolved when sodium metal (Na) is reacted with dilute HCl. The reaction is of exothermic nature. Therefore, hydrogen catches fire accompanied by explosion.
`2"Na"("s") + 2"HCl" ("aq") -> 2"NaCl"("aq") + "H"_2("g")`
Remember : Sodium metal as such does not catch fire. It is the hydrogen gas evolved which burns since the reaction is highly exothermic in nature.
संबंधित प्रश्न
The colours of aqueous solutions of CuSO4 and FeSO4 as observed in the laboratory are:
(A) pale green and light blue respectively
(B) light blue and dark green respectively
(C) dark blue and dark green respectively
(D) dark blue and pale green respectively
Identify from the reaction the reactants that undergo oxidation and reduction.
2Mg + O2 → 2MgO
Compare hydrogen with alkali metals on the basis of:
Oxide formation
In what respect does hydrogen differ from:
alkali metals
Give the general group study of hydrogen with reference to
burning
Divide the following reactions into oxidation and reduction half-reaction:
Zn + Pb2+→ Pb + Zn 2+
Reacting with water, an active metal produces
Name:
a liquid that is an oxidizing agent as well as a reducing agent.
Complete and balance the following equation:
H2 + S → ___________
Complete and balance the following equation:
Zn +_________________→ZnCl2 + H2
State a reason why, when hydrogen is passed over heated copper oxide, the resultant product formed, differs in colour from the original reactant.
Select the correct answer from the symbol in the bracket.
The element, which like hydrogen is a strong reducing agent.
In the reaction of iron with copper sulphate solution:
CuSO4 + Fe → Cu + FeSO4
Which option in the given table correctly represents the substance oxidized and the reducing agent?
| OPTION | Substance Oxidized | Reducing Agent |
| A | Fe | Fe |
| B | Fe | FeSO4 |
| C | Cu | Fe |
| D | CuSO4 | Fe |
Identify the reducing agent in the following reactions
`4"NH"_3 + 5"O"_2 -> 4"NO" + 6"H"_2"O"`
Identify the reducing agent in the following reactions
`2"H"_2 + "O"_2 -> 2"H"_2"O"`
Identify the oxidising agent (oxidant) in the following reactions
`2"Mg" + "O"_2 -> 2"MgO"`
Which among the following are physical or chemical change?
Curding of milk
A silver article generally turns black when kept in the open for a few days. The article when rubbed with toothpaste again starts shining.
- Why do silver articles turn black when kept in the open for a few days? Name the phenomenon involved.
- Name the black substance formed and give its chemical formula.
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?
Find the oxidation number of the element in the following compound.
Zn in ZnSO4
