Question

At 900 °C titanium tetrachloride vapor reacts with molten magnesium metal to form solid titanium metal and molten magnesium chloride.Which substance is the reductant, and which is the oxidant?

Answer 1

Part A.

Let the oxidation number of Ti in titanium tetrachloride be 'x'. The oxidation number of the chlorine atom is -1.

Thus,

x + 4(-1) = 0

or x = +4

In the products, Ti is present in the elemental state and thus its oxidation number is zero. Thus, the oxidation number is reduced.

Magnesium is in the elemental state in the reactant with oxidation number zero and in the products, it is present as magnesium chloride. Let the oxidation no. of Mg in magnesium chloride be 'y'.

Thus,

y + 2(-1) = 0

or, y = +2

Thus, the oxidation state of Mg is increased.

Thus,

Mg is oxidized

T
i
C
l
4
is reduced.

_____

Part C:

The reductant (or reducing agent) is a species that itself gets oxidized and reduces other species. Oxidant (or oxidizing agent) is a species that itself gets reduced and oxidizes the other species.

Thus, the reductant is Mg and oxidant is
T
i
C
l
4