Question

What may be expected to happen when phosphine gas is mixed with chlorine gas?
A. $PC{l_3}$ and $HCl$ are formed and the mixture warms up.
B. $PC{l_3}$ and $HCl$ are formed and the mixture cools down.
C. The mixture only cools down.
D. None of the above.

Answer 1

Hint: We know that the molecular formula of phosphine gas is $P{H_3}$. The molecular formula of chlorine gas is $C{l_2}$. Phosphine is a very toxic gas. Phosphine is a Lewis base because the phosphorus in the phosphine molecule has a lone pair.

Complete step by step answer:
We know that phosphine is a very toxic gas. Its smell is similar to that of rotten fish. Chlorine is also a toxic gas. So whenever phosphine gas is mixed with chlorine gas it forms $PC{l_3}$ and $HCl$. The chemical equation can be written as $P{H_3} + 3C{l_2} \to PC{l_3} + 3HCl$. The mixture warms up after $PC{l_3}$ and $HCl$are formed .The reaction between phosphine gas and chlorine gas is an explosive reaction. Explosive reactions release heat, so it is an example of exothermic reaction. So from the above explanation it is clear to us that the correct answer of the given question is : A. $PC{l_3}$ and $HCl$ are formed and the mixture warms up.

Hence option A is correct.

Additional information:
 Phosphine gas explodes with traces of oxidising agents like $C{l_2},HN{O_3},B{r_2}$. Chlorine was used in World War $1$. It is used in explosives. Chlorine is very harmful for human beings and it can damage the respiratory tract . Hydrochloric acid is a very strong acid. Direct skin contact of hydrochloric acid can cause severe burns. Phosphine is used in semiconductor industries. It is used to introduce phosphorus in the silicon crystals.

Note:
Always remember that phosphine gas is a very toxic gas. It explodes with chlorine gas to produce $PC{l_3}$ and $HCl$. Explosive reactions release heat so they are exothermic reactions. The reaction of phosphine gas and chlorine gas can be written as $P{H_3} + 3C{l_2} \to PC{l_3} + 3HCl$