Question

a student was given mg, Zn, Fe and Cu metals he put each of them in dilute HCl contained in four fifferent test tubes identify which of them i) will not displaced hydrogen from dilute HCL. ii) forms a pale green substance iii) will give hydrogen with very dilute nitric acid iv) will be displaced from its salt solution by all other metals
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Answer 1

Answer:

Explanation:

$\boxed{\huge{\sf{\blue{Answer}\pink{:-}}}}$

1. According to reactivity series,

• K Potassium

•Na Sodium

• Ca Calcium

•Mg Magnesium

•Al Aluminium

•Zn Zinc

•Fe Iron

•Sn Tin

•Pb Lead

•H Hydrogen

•Cu [Written till copper]

Copper is less reactive than hydrogen, so, it will not get displaced ie no change in solution is observed.

2. We know that when iron will react with Hydrochloric Acid, it will give us green color.

3. The only elements which give us Nitric Acid is manganese and magnesium. So, Magnesium will give us HNO3.

$\huge{\sf{\blue{Required \ Equations}}}$

$\sf{Fe + 2HCl \longrightarrow FeCl_2 + H_2}$

• Fe is iron
• HCl is Hydrochloric Acid
• Iron chloride is FeCl2
• H2 is Hydrogen.

$\sf{Mg + 2HCl \longrightarrow MgCl_2 + H_2}$

• Mg is Magnesium
• HCl is Hydrochloric Acid
• Magnesium chloride is MgCl2
• H2 is Hydrogen.

$\sf{Zn + 2HCl \longrightarrow ZnCl_2 + H_2}$

• Zn is Zinc
• HCl is Hydrochloric Acid
• Zinc chloride is ZnCl2
• H2 is Hydrogen.

These all are Displacement reactions.

Answer 2

Answer :-

$\:\:\:\underline{\boxed{\tt{\red{Understanding \: the \: concept \:}}}}$

Here the concept of Displacement reaction has been used. According to this, more reactive element displaces less reactive element from its salt solution. After displacement, the more reactive element forms compound with basic constituent and the less reactive element gets seperated from compound.

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★ Solution :-

i) will not displaced hydrogen from dilute HCL ?

Answer.) Copper (Cu) is not going to release Hydrogen gas (H) when it is put in dilute HCl solution. This is because copper is less reactive reactive than every other metal, that is Zinc (Zn) , Iron (Fe) and Magnesium (Mg). Also, we know that when Acid and metals react, Hydrogen gas is displaced only when the reactive metal is more reactive than Hydrogen in reactivity series. We know that, Copper comes below Hydrogen and is less reactive than Hydrogen. So it will not displace hydrogen gas when put in dilute HCl.

ii.) forms a pale green substance ?

Answer.) Iron (Fe) is going to form a pale green substance in test tube. This is because Iron (Fe) being more reactive than Hydrogen displaces Hydrogen gas from HCl and forms Ferrous Chloride. The reaction is as follows :-

$\: \: \blue{\rm{Fe_{(s)}} \: + \: \rm{2HCl_{(aq)}} \: \longrightarrow \: \: \rm{FeCl_{2} \: _{(aq)}} \: + \: \rm{H_{2} \: _{(g)}}}$

Hence, Iron will be the answer.

iii.) will give hydrogen with very dilute nitric acid ?

Answer.) Magnesium (Mg) will give hydrogen gas with very dilute nitric acid. This is because Magnesium is high reactive element which reacts with hot dilute nitric acid giving Magnesium Nitrate and Hydrogen gas as the product. The reaction is as follows :-

$\: \: \green{\rm{Mg_{(s)}} \: + \: \rm{2HNO_{3} \: _{(aq)}} \: \longrightarrow \: \: \rm{Mg(NO_{3})_{2} \: _{(aq)}} \: + \: \rm{H_{2} \: _{(g)}}}$

iv.) will be displaced from its salt solution by all other metals ?

Answer.) Copper (Cu) is the element will be the one which will be displaced from its salt solution by all other metals that is Zinc (Zn), Magnesium (Mg) and Iron (Fe). This is because Copper is the least reactive element among all the given elements. Mg > Zn > Fe > Cu. This is given as reactivity series for given elements. This follows displacement reaction.

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$\:\:\underline{\purple{\boxed{\sf{Refer \: to \: Supplementary \: Artefacts \: !! \:}}}}$

• Reactivity series is given as :-

Potassium (K) > Sodium (Na) > Calcium (Ca) > Magnesium (Mg) > Aluminum (Al) > Zinc (Zn) > Iron (Fe) > Lead (Hg) > Hydrogen (H) > Copper (Cu) > Silver (Ag) > Platinum (Pt) > Gold (Au)

Potassium is considered most reactive element and Gold is considered least reactive element.

✒ Different types of reactions are :-

• Combination Reaction - The reaction in which two or more elements or compounds to form one product is known as combination reaction.

• Decomposition Reaction - The reaction in which one compound decomposes into two or more compounds by the action of any form of energy like heat, sunlight and electricity,etc.

• Double Displacement Reaction - The reaction in which two compounds on reacting change their ions or radicals is known as double displacement reaction.

• Magnesium (Mg) and Manganese (Mn) are the only elements which react to give displaced hydrogen gas in dilute nitric acid.