Question

List the important sources of sulphur.
Write the order of hydride stability of the hydrides of group 16 elements.
Why is ${{H}_{2}}O$ liquid and ${{H}_{2}}S$ gas?

Answer 1

The group 16 elements of the modern periodic table consist of 5 elements oxygen, sulphur, selenium, tellurium and polonium. The elements in this group are also known as ore-forming elements because many elements can be extracted from the sulphide or oxide ores.

Complete step by step solution:
Sulphur mainly exists in combined form within the crust primarily as sulphates [ gypsum ($CaS{{O}_{4}}.2{{H}_{2}}O$),
Epsom salt ($MgS{{O}_{4}}.7{{H}_{2}}O$), baryte ($BaS{{O}_{4}}$) ] and sulphides [ (galena ($PbS$), zinc blends ($ZnS$),
Copper pyrites ($CuFe{{S}_{2}}$ )].
These are the sources of sulphur.
The next question is about the order of hydride stability of the hydrides of group 16.
The thermal stability of the hydrides of group 16 elements decreases down the group. This is often because M-H bond dissociation energy decreases down the group with the rise in the size of the central atom.
So the correct order of the steadiness of the hydrides is
${{H}_{2}}O\,>\,{{H}_{2}}S\,>\,{{H}_{2}}Se\,>{{H}_{2}}Te\,>\,{{H}_{2}}Po$
H2O has oxygen as the central atom. Oxygen has smaller size and higher electronegativity as compared to sulphur. Therefore, there is extensive hydrogen bonding in${{H}_{2}}O$, which is absent in${{H}_{2}}S$. Molecules of ${{H}_{2}}S$ are held together only by weak van der Waals forces of attraction. Hence, ${{H}_{2}}O$ exists as a liquid while ${{H}_{2}}S$ as a gas.

Additional information:
Tellurium is a chemical element having atomic number 52 and has the properties between metals and nonmetals. It is one of the rarest stable elements found in the earth’s crust. It is often found in a free state and in compounds with elements such as copper, lead, silver or gold.
Polonium is the rarest element among the group 16 elements. It is a radioactive element. Polonium is sometimes used in scientific applications for alpha radiation.

Note: In inorganic chemistry the various trends in the groups are very important. Without knowing this these types of questions are difficult to solve. Group is also known as the oxygen family or chalcogens.