Chemistry Of Hydrogen

Question 1

How is hydrogen industrially prepared that results in an important fuel?

Answer 1

Hydrogen is prepared by passing steam over red hot coke (Bosch process).

C + H2O =100°C=> CO + H2

The product is water gas.

Question 2

How is hydrogen produced from hydrocarbons?

Answer 2

Hydrogen is produced from light hydrocarbons by their reaction with steam in the presence of nickel catalyst and high temperature:

CH4 + H2O(g) ==Ni==> CO + 3H2

This is the steam reformer process and its product is synthesis gas.

Question 3

Why is water gas important?

Answer 3

Water gas is used as industrial fuel because it is easy to make and burns, emitting large amount of heat.

Question 4

How is CO removed from water gas?

Answer 4

By liquefying water gas at low temperature and high pressure which gives H2 only.

Question 5

How is hydrogen produced industrially that involves metals?

Answer 5

Hydrogen is produced industrially by the electrolysis of dilute NaOH, KOH, or NaCl.

Question 6

How can hydrogen be produced from metals and acids (laboratory preparation)?

Answer 6

Hydrogen can be produced in the laboratory by reacting metals higher in the electrochemical series than hydrogen with mineral acids:

2HCl_(aq) + Mg_(s) ==> MgCl_{2 (aq)} + H_{2 (g)}

Zn + H2SO4 ==> ZnSO4 + H2

Question 7

How can hydrogen be prepared (in the laboratory) which involves metals and water?

Answer 7

Na, K, and Ca react with cold water to produce hydrogen gas.

2Na +2H2O ==> 2NaOH +H2O

Question 8

How can hydrogen be prepared (in the lab) using steam and metals?

Answer 8

Mg, Al, Fe, Sn, and Pb react with steam to produce hydrogen.

Mg + 2H2O ==> Mg(OH)2 + H2

Question 9

What are hydrides?

Answer 9

Hydrides are compounds formed by hydrogen.

Question 10

What are the types of hydrides?

Answer 10

1. Ionic hydrides (formed from Group I and II)
2. Covalent hydrides (fromed from Group III - VII)
3. Metallic hydrides (formed from Transition elements)

Question 11

Which isotope of hydrogen does not have a neutron?

Answer 11

Protium

Question 12

Which hydrogen is radioactive?

Answer 12

Tritium.

Question 13

Arrange LiH, CsH, and NaH in increasing order of ionic character.

Answer 13

LiH < NaH < CsH.

This is because ionic character increases as one goes down the group. Ionic character can be seen as the “willingness” for an atom to release its outermost electron, this becoming an atom.

Question 14

Why does H₂O have higher Melting point than H₂S?

Answer 14

The hydrogen bond in H2O, formed due to the attraction of protons to the more electronegative oxygen, is stronger than the Van Der Waal forces in H2S.