Question

When chlorine gas and hydrogen gas react to form hydrogen chloride, what will be the change of enthalpy of the reaction?

Answer 1

Step-by-step explanation:

Reaction between chlorine and hydrogen gas will take place as follows.

`Cl_(2)(g) + H_(2)(g) \rightarrow 2HCl(g)`

Since, standard enthalpy of
`Cl_(2)(g)` is 0 kJ/mol and
`H_(2)(g)` is also 0 kJ/mol.
`\Delta H_(HCl)` is -92.30 kJ/mol.

Hence, change in enthalpy will be calculated as follows.

`\Delta H = \Delta H_(products) - \Delta H_(reactants)`

= (-92.30 - 0) kJ/mol

= -ve

Also, formation of bonds is taking place between both chlorine and hydrogen atoms. As a result, heat will be released during this process.

Thus, we can conclude that change in enthalpy will be negative.