Question

3) In the reaction between iron and copper sulphate the colour change from blue to green is due to the formation of

1) Aluminium sulphate
2) Ferrous sulphate
3) Zinc sulphate
4) Magnesium sulphate​

Answer 1

Answer:

Answer is (2) Ferrous sulphate

Explanation:

Iron displaces copper ions from an aqueous solution of copper sulphate. It is a single displacement reaction of one metal by another metal. Iron is placed above copper in the activity series.

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Answer 2

Answer:

Pls mark as brainliest

Explanation:

Iron is an el­e­ment of the eighth group of the fourth pe­ri­od in the Pe­ri­od­ic Ta­ble. It is a mal­leable sil­very met­al with good elec­tro­con­duc­tiv­i­ty and pro­nounced mag­net­ic prop­er­ties. In na­ture iron is main­ly en­coun­tered in an ox­i­dized state – for ex­am­ple brown iron ore Fe₂O₃·3H₂O, red iron ore Fe₂O₃ (hematite), pyrite FeS₂, mag­net­ic iron ore Fe₃O₄.

Ob­tain­ing iron and its re­ac­tion with sim­ple sub­stances

Iron

Metal­lic iron is ob­tained in in­dus­try by re­duc­ing it from iron ox­ide with car­bon monox­ide CO:

Ob­tain­ing car­bon (IV) ox­ide from coal:

C + O₂ = CO₂;

Ob­tain­ing car­bon II ox­ide (re­duc­er for ob­tain­ing iron):

CO₂ + C = 2CO;

Re­duc­tion of iron from iron ox­ide:

Fe₂O₃ + 3CO = 2Fe + 3CO₂.

Iron can also be ob­tained di­rect­ly by re­duc­ing it with hy­dro­gen at a tem­per­a­ture of 1000 ᵒC (1832 ᵒF):

Fe₂O₃ + 3H₂ = 2Fe + 3H₂O.

Chem­i­cal­ly pure iron is ob­tained by elec­trol­y­sis of the so­lu­tion of its salt:

K(-): 1) 2H₂O + 2e = H₂ + 2OH⁻;

Fe²⁺ + 2e = Fe(0).

A(+): 2H₂O - 4e = O₂ + 4H⁺.

Sum­mar­i­ly:

Fe­S­O₄ + 2H₂O = Fe + H₂ + O₂ + H₂­SO₄.

With non-met­als, iron re­acts at high tem­per­a­tures:

3Fe + 2O₂ = Fe₃O₄ (a mix­ture of iron (II) and (III) ox­ides form);

Fe + S = FeS;

2Fe + 3Br₂ = 2FeBr₃.

Fe₃O₄ [Wikimedia]

Re­ac­tions of iron with com­plex sub­stances

At a tem­per­a­ture of 700 ᵒC (1292 ᵒF), iron re­acts with ben­zol with the for­ma­tion of iron car­bide:

18Fe + C₆H₆ = 6Fe₃C + 3H₂.

At room tem­per­a­ture in air and in the pres­ence of mois­ture, iron cor­rodes (cor­ro­sion is the spon­ta­neous dis­in­te­gra­tion of met­al un­der the im­pact of the en­vi­ron­ment):

4Fe + 3O₂ + 6H₂O = 4Fe(OH)₃ (re­ac­tion takes place rather slow­ly in nor­mal con­di­tions).

Corrosion [Wikimedia]

When iron is fused with an al­ka­li in the pres­ence of ni­trate, fer­rates form on the cation of the al­ka­li:

Fe + 3NaNO₃ + 2NaOH = Na₂FeO₄ + 3NaNO₂ + H₂O.

Click here for ex­cit­ing ex­per­i­ments with iron.

Iron en­ters into a dis­place­ment re­ac­tion read­i­ly (re­ac­tions in which atoms or groups of atoms of the same ini­tial sub­stance re­place atoms or groups of atoms of an­oth­er ini­tial sub­stance – for ex­am­ple ac­cord­ing to the scheme АВ + С = АС + В). With di­lut­ed acids, iron re­acts with the for­ma­tion of iron (II) salt and hy­dro­gen:

Fe + 2HCl = Fe­Cl₂ + H₂.

Con­cen­trat­ed ni­tric acid (and con­cen­trat­ed cold sul­fu­ric acid) pas­si­vates iron, and this re­ac­tion does not take place. With con­cen­trat­ed hot sul­fu­ric acid and di­lut­ed ni­tric acid, acid re­acts as fol­lows:

Fe + 6H₂­SO₄ = Fe₂(SO₄)₃ + 3SO₂ + 6H₂O (only with heat­ing);

Fe + 4H­NO₃ = Fe(NO₃)₃ + NO + 2H₂O.

With salts, iron may also en­ter into a dis­place­ment re­ac­tion. Be­tween cop­per (II) sul­fate and metal­lic iron, the fol­low­ing re­ac­tion takes place (an ex­am­ple of a typ­i­cal dis­place­ment re­ac­tion be­tween in­or­gan­ic sub­stances):

Fe + Cu­SO₄ = Fe­S­O₄ + Cu (iron dis­places cop­per in the salt so­lu­tion; the iron dis­solves, turn­ing into so­lu­tion, and metal­lic cop­per of a red­dish col­or is re­leased).

Copper sulfate [Wikimedia]

The re­ac­tion does not take place in this way with all salts – dis­place­ment is only pos­si­ble if the dis­plac­ing met­al is more re­ac­tive than the dis­placed one. As iron is to the left of cop­per in the re­ac­tiv­i­ty se­ries (is re­ac­tiv­i­ty in the se­ries de­creas­es from left to right), we may say that iron is a more ac­tive met­al than cop­per. This is why it dis­places cop­per from cop­per salt so­lu­tion.

We may ob­serve some vis­ual ef­fects when car­ry­ing out this re­ac­tion. Cu­SO₄ (“cop­per sul­fate” or cop­per (II) sul­fate) is a salt with a bluish col­or. When a sil­very iron bar is put in a cop­per sul­fate so­lu­tion, the so­lu­tion slow­ly starts to change col­or – the bright blue col­or grad­u­al­ly turns green (the salt Fe­S­O₄ which forms in re­place­ment has a green col­or). Metal­lic cop­per of a red­dish col­or also starts to form around the dis­solv­ing iron bar. As the cop­per in this re­ac­tion has a rather loose struc­ture, it may sep­a­rate from the iron bar and pre­cip­i­tate.

The re­ac­tion be­tween cop­per sul­fate and iron is ox­i­da­tion-re­duc­tion: iron is ox­i­dized and cop­per is re­duced:

Fe + Cu­SO₄ = Fe­S­O₄ + Cu;

There are two pro­cess­es:

Cu²⁺ + 2e = Cu⁰ (re­duc­tion process, Cu²⁺ is the ox­i­diz­er);

Fe⁰ – 2e = Fe²⁺ (ox­i­da­tion process, Fe⁰ is the re­duc­er).