Question

In which of the following compounds does hydrogen has an oxidation state - 1?
a) Methane
b) Calcium Hydride
c) Water
d) Hydrochloric Acid

Eliminate options yet justifying them

Thank You ​

Answer 1

Answer:

Given:

4 compounds have been provided as follows :

• Methane ( CH4)
• Calcium Hydride (CaH2)
• Water ( H2O)
• Hydrochloric Acid (HCl)

To find:

Compound having oxidation state of -1

Concept:

Oxidation State or Oxidation Number is the number assigned to an element denoting the number of electrons lost or gained.

Elimination:

We will arrive at the answer by elimination method.

1. Methane (CH4) : Carbon is more negative than Hydrogen , hence oxidation state of carbon = -4.

So, -4 + 4x = 0

=> x = 4/4 = +1 .....(OXIDATION STATE OF HYDROGEN IS POSITIVE).

So, option 1) eliminated.

2. CaH2 (Calcium Hydride):

Ca is more electro-positive.

So, +2 + 2x = 0

=> x = -2/2 = -1 ( OXIDATION STATE IS NEGATIVE FOR HYDROGEN)

so, option 2) accepted.

3. Water(H2O):

Oxygen is electro-negative.

So, -2 + 2x = 0

=> x = +2/2 = +1 ......(OXIDATION STATE OF HYDROGEN IS POSITIVE)

so, option 3) is eliminated.

4. Hydrochloric Acid (HCl):

Chlorine is more electro-negative.

So, -1 + x = 0

=> x = +1 ......(OXIDATION STATE OF HYDROGEN IS POSITIVE)

so, option 4) is eliminated.

So option 2) is correct.

Answer 2

Answer:

• In Calcium Hydride The Hydrogen Exhibits - 1 Oxidation State.

Explanation:

$\rule{300}{1.5}$

Methane :-

Methane has a General Formula of CH₄. In the Compound Four Hydrogen (H) atoms are Associated with one Carbon (C) Atom.

Now, In CH₄, the Carbon atom has a Electronegativity  of 2.5 & Hydrogen has a Electronegativity of 2.1.

Since, Here We can see that the Carbon atom is more Electronegative than Hydrogen, Then carbon will pull the Bonded Pair of Electrons towards Itself and acquire Negative Charge of ( - 4) And hydrogen's Will Acquire  Positive Charge of ( + 1) on Itself.

∴ This is Not The Correct Option As Oxidation state of Hydrogen is + 1 in this case.

$\rule{300}{1.5}$

$\rule{300}{1.5}$

Calcium Hydride:-

Calcium Hydride has a General Formula of CaH₂. In the Compound two Hydrogen (H) atoms are Associated with one Calcium (Ca) Atom.

Now, In CaH₂, the Calcium atom has a Electronegativity  of 1 & Hydrogen has a Electronegativity of 2.1.

Since, Here We can see that the Hydrogen atom is more Electronegative than Calcium, Then Hydrogen  will pull the Bonded Pair of Electrons towards Itself and acquire Negative Charge of ( - 1) And calcium Will Acquire  Positive Charge of ( + 2) on Itself.

∴ This is The Correct Option As Oxidation state of Hydrogen is - 1in this case.

$\rule{300}{1.5}$

$\rule{300}{1.5}$

Water:-

Water has a General Formula of H₂O. In the Compound two Hydrogen (H) atoms are Associated with one Oxygen (O) Atom.

Now, In H₂O, the Oxygen atom has a Electronegativity  of 3.44 & Hydrogen has a Electronegativity of 2.1.

Since, Here We can see that the Oxygen atom is more Electronegative than Hydrogen, Then Oxygen  will pull the Bonded Pair of Electrons towards Itself and acquire Negative Charge of ( - 2) And hydrogen's Will Acquire  Positive Charge of ( + 1) on Itself.

∴ This is Not The Correct Option As Oxidation state of Hydrogen is + 1 in this case.

$\rule{300}{1.5}$

$\rule{300}{1.5}$

Hydrochloric Acid:-

Methane has a General Formula of HCl . In the Compound one Hydrogen (H) atoms are Associated with one Chlorine (Cl) Atom.

Now, In HCl, the Chlorine atom has a Electronegativity  of 3.16 & Hydrogen has a Electronegativity of 2.1.

Since, Here We can see that the Chlorine atom is more Electronegative than Hydrogen, Then chlorine will pull the Bonded Pair of Electrons towards Itself and acquire Negative Charge of ( - 1) And hydrogen's Will Acquire  Positive Charge of ( + 1) on Itself.

∴ This is Not The Correct Option As Oxidation state of Hydrogen is + 1 in this case.

$\rule{300}{1.5}$