Inorganic Chemistry Test - 1

Hydrogen chloride (HCl) is a colourless gas of strong odour. It condenses at -85°C (-121°F) and freezes at -114°C (-173°F). The gas is highly soluble in water; at 20°C (68°F), water will dissolve 477 times its own volume of hydrogen chloride. As a result of its great solubility, the gas fumes in moist air.

Any substance can act as an oxidising or reducing agent if one of the elements in the given compound is present in its intermediate oxidation state. Thus, during the reaction, it can either increase or decrease its oxidation number. For example, in SO₂, the oxidation number of sulphur is +4. In principle, S can have minimum oxidation number of -2 and maximum of +6. Therefore, S in SO₂ can either decrease or increase its oxidation number and hence can act both as an oxidising as well as reducing agent.

Sulphur dioxide is a colourless gas with a pungent, suffocating odour. It is a dangerous air pollutant because it is corrosive to organic materials and it irritates the eyes, nose and lungs.

SO₂ turns lime water milky, so does carbon dioxide.

Newspaper turns yellow on prolonged exposure to atmosphere because of oxidation. Paper is made from wood, which is made up mainly of white cellulose. Wood also has a lot of a dark substance in it called lignin, which ends up in the paper, too, along with the cellulose. The exposure of lignin to air and sunlight is what turns paper yellow.

Bromine water and potassium dichromate in the acidic medium are stronger oxidising agents and can oxdise SO₂.
The colour change with KMnO₄ will be pinkish violet to colourless.

SO₂ bleaches by reduction and acts as a temporary bleach for vegetable matter.

H₂S destroys the haemoglobin in the blood.

At 770°C temperature, the thermal decomposition of H₂S is completed.

H₂S acts as a reducing agent.

H₂S₂O₇ is the chemical formula of oleum.