Consider these reactions, where M represents a generic metal. 2 M ( s ) + 6 HCl ( aq ) ⟶ 2 MCl 3 ( aq ) + 3 H 2 ( g ) Δ H 1 = − 760.0 k J HCl ( g ) ⟶ HCl ( aq ) Δ H 2 = − 74.8 k J H 2 ( g ) + Cl 2 ( g ) ⟶ 2 HCl ( g ) Δ H 3 = − 1845.0 k J MCl 3 ( s ) ⟶ MCl 3 ( aq ) Δ H 4 = − 267.0 k J Use the given information to determine the enthalpy of the reaction 2 M ( s ) + 3 Cl 2 ( g ) ⟶ 2 MCl 3 ( s )

Answer : The enthalpy of the reaction is, -6209.8 kJ

Explanation :

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.

The Main reaction is:

The intermediate balanced chemical reaction will be,

(1)    

(2)    

(3)    

(4)    

We are multiplying equation 3 by 3, reverse reaction of 4 by 2 and reaction 2 by 6 and then adding all the equations, we get :

(1)    

(2)    

(3)    

(4)    

The expression for enthalpy of the reaction is,

Therefore, the enthalpy of the reaction is, -6209.8 kJ

hurricanes form when warm, moist air from the ocean surface quickly rises into the atmosphere and forms storm clouds and rain. when the clouds are formed, heat is released which warms the cool air in the upper regions of the atmosphere so that the cycle can continue. which two phases of the water cycle are repeated in this process?