Write the valency of the following :?

Question

1.Sodium in Na2 S
2.Nitrogen in N O2
3.Nitogen in N H3
4.Sulphur in H2 S
5.Phosphorus in P2 O5
6.Aluminium in Al2 O3
7.Magnesium in Mg3 N2
8.Calcium in CaO

Give valencies & chemical formula of the following compounds :
9.Zinc Carbonate
10.Ammonium sulphide
11.Barium chloride
12.Sodium nitrate
13.Ferric Sulphate
14.Calcium Carbonate
15.Potassium dichromate
16.Sodium nitrite
17.Copper (II) oxide
18.Sodium zincate

In above questions also explain how to find out valancies so that I can myself solve for valancies. If don't know only answer the questions but correctly.

Answer 1

1.-2

2.+4

3.+3

4.-2

5.+5

6.+3

7.+2

8.+2

9. ZnCO3

Zn +2

C +4

O -2

10. (NH4)2S

N +5

H -1

S -2

11. BaCl2

Ba +2

Cl -1

12. NaNO3

Na +1

N +5

O -2

13. Fe2(SO4)3·9H2O

Fe +3

S +4

O -2

H +1

14. CaCO3

Ca +2

C +4

O -2

15. K2Cr2O7

K +1

Cr +6

O -2

16. NaNO2

Na +1

N +3

O -2

17. CuO

Cu +2

O -2

18. Na2ZnO2

Na +1

Zn +3

O -2



To find out the valencies, compound must have valencies of zero. All elements must add up to zero except if the compound is not zero.

Answer 2

Nitrate Valency

Answer 3

N = 3 Br = 1 Be=2 S = 2 He = 2 H = 1 Li = 1 Ba = 1 please choose as best answer all valencies are right

Answer 4

First, I'd like to tell that valancy is difference with oxidation number. Notice that for valancy every elements (especially not-center element) are not the same with its oxidation number. But for valancy every center elements have the same with its oxidation number.

Valancy is amount of electron in the reaction of reduction-oxidation (by the mean : can use amount of electron in reduction or oxidation) every one mole. So the origin formula is : Valancy = amount of electron / mole



E.g. Na2S

Na ---> Na+ + e |2x| ====> 2Na ---> 2Na+ + 2e

S + 2e ---> S^2- |1x| ====> S + 2e ---> S^2-

[Eliminate the 2 electrons there...]

---------------------------------------------------------------------- +

Na + S ---> 2Na+ + S^2- or Na + S ---> Na2S

(One coefficient Na2S shows one mole)



Valance of Na2S = "amount of electron in reduction" OR "amount of electron in oxidation" = 2

By the mean : amount of electron in one of electrodes (if we use electrolisis experiment)



Easily, we count it by : multiplying valance of one of elements by amount of element in its molecule.

E.g. Na2S

Na2S have 2 element of Na ; Na has +1 in valancy.

So valancy of Na2S = 1 x 2 = 2



Or,



We can also count from S element.

Na2S have 1 element of S ; S valancy = -2

Valancy = 2 x 1 = 2



{skipping the charge (+/-) of element valancy}



If you enable to count the valancy of each element, you can use only its reaction.

E.g. Na in Na2S

After balancing electrolysis equation we get :

Na ---> Na+ + e |2x| ====> 2Na ---> 2Na+ + 2e



2Na ---> 2Na+ + 2e

In reaction above, we know 2 electrons is used for 2 mole (=coefficient) of Na.

So, valancy = amount of electron / mole = 2 / 2 = 1



2.Nitrogen in N O2 = 4

3.Nitogen in N H3 = 3

4.Sulphur in H2 S = 2

5.Phosphoruses in P2 O5 = 10 (for 2 Phosphoruses)

6.Aluminium in Al2 O3 = 6 (for 2 Aluminiums)

7.Magnesium in Mg3 N2 = 6 (for 2 Magnesium)

8.Calcium in CaO = 2

9.Zinc Carbonate (ZnCO3) = 2

10.Ammonium sulphide [(NH4)2 SO3] = 2

11.Barium chloride (BaCl2) = 2

12.Sodium nitrate (NaNO3) = 1

13.Ferric Sulphate [Fe2(SO4)3] = 6

14.Calcium Carbonate (CaCO3) = 2

15.Potassium dichromate (K2Cr2O7) = 2

16.Sodium nitrite (NaNO2) = 1

17.Copper (II) oxide (CuO) = 2

18.Sodium zincate (Na2ZnO2) = 2

Answer 5

1.Sodium in Na2 S

Valency of Na is 1 and oxidation state is +1

Valency of S is 2 and the oxidation state is -2

2.Nitrogen in N O2

Valency of N is 4 and oxidation state is +4

Valency of O is 2 and the oxidation state is -2

3.Nitogen in N H3

Valency of N is 3 and oxidation state is +3

Valency of H is 1 and the oxidation state is -1

4.Sulphur in H2 S

Valency of H is 1 and oxidation state is +1

Valency of S is 2 and the oxidation state is -2

5.Phosphorus in P2 O5

Valency of P is 5 and oxidation state is +5

Valency of O is 2 and the oxidation state is -2

6.Aluminium in Al2 O3

Valency of Al is 3 and oxidation state is +3

Valency of O is 2 and the oxidation state is -2

7.Magnesium in Mg3 N2

Valency of Mg is 2 and oxidation state is +2

Valency of N is 3 and the oxidation state is -3

8.Calcium in CaO

Valency of Ca is 2 and oxidation state is +2

Valency of O is 2 and the oxidation state is -2



Valency can be calculated based on the availability of electrons for bonding or in other terms, no. of electrons take part in bonding



Oxidation represents the number of electrons donated or gained. If the element has positive oxidation state means, it donates electrons for bonding and if the oxidation is negative value means it accepts electrons for bonding. In other term, electrons donated or gained is to attain the noble electronic configuration (Completely filled orbitals)



9.Zinc Carbonate

Formula is ZnCO3

Valency of Zn is 2 and oxidation state is +2

Valency of C is 4 and the valency of O is 2 , but overall oxidation state for CO3 is -2

The electronic structure of (CO3) 2- is ---O---C(=O)---

10.Ammonium sulphide

Formula is (NH4)2 S

Valency of N is 3 and the valency of H is 1 , but overall oxidation state for NH4 is +1

Valency of S is 2 and oxidation state is -2

11.Barium chloride

Formula is BaCl2

Valency of Ba is 2 and oxidation state is +2

Valency of Cl is 1 and oxidation state is -1

12.Sodium nitrate

Formula is NaNO3

Valency of Na is 1 and oxidation state is +1

Valency of N is 3 and the valency of O is 2 , but overall oxidation state for NO3 is -1

13.Ferric Sulphate

Formula is Fe2 (SO4)3

Valency of Fe is 3 and oxidation state is +3

Valency of S is 6 and the valency of O is 2 , but overall oxidation state for SO4 is -2

14.Calcium Carbonate

Formula is CaCO3

Valency of Ca is 2 and oxidation state is +2

Valency of C is 4 and the valency of O is 2 , but overall oxidation state for CO3 is -2

15.Potassium dichromate

Formula is K2Cr2 O7

Valency of K is 1 and oxidation state is +1

Valency of Cr is 6 and the valency of O is 2 , but overall oxidation state for Cr2 O7 is -2

16.Sodium nitrite

Formula is NaNO2

Valency of Na is 1 and oxidation state is +1

Valency of N is 3 and the valency of O is 2 , but overall oxidation state for NO2 is -1

17.Copper (II) oxide

Formula is CuO

Valency of Cu is 2 and oxidation state is +2

Valency of O is 2 and oxidation state is +2

18.Sodium zincate

Formula is Na2 ZnO2

Valency of Na is 1 and oxidation state is +1

Valency of Zn is 2 and the valency of O is 2 , but overall oxidation state for Zn O2 is -2

Answer 6

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