Given that H2(g) + F2(g) - > 2HF(g) delta H rxn = -546.6 kJ 2H2(g)+ O2(g) - > 2H2O(l) delta H rxn = 571.6 kJ calculate the value of delta H rxn for 2F2(g)+2HO(l) - > 4Hf(g)+O2(g)

Answer : The value of for the reaction is, -1664.8 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)    

Now we are reversing reaction 2 and multiplying reaction 1 by 2 then adding both the equations, we get :

(1)    

(2)    

The expression for enthalpy of the given reaction will be:

Therefore, the value of for the reaction is, -1664.8 kJ

the correct answer is b. a strong acid completely dissociates to its ions when dissolved in water. completely dissociates to and ions. a is incorrect because does not fully ionize to and ions and some remain as the compound . c and d are incorrect because, and do not fall into the category of bronsted lowry acids. a bronsted lowry acid is a proton donor and since both molecules do not have a proton to donate they are not bronsted lowry acids. likewise,   if we use the lewis acid definition, they cannot be acids. a lewis acid is an electron pair acceptor. both and have a complete octet so can not accept any electrons which disqualifies them as acids.