A positive cahnge of enthalpy, ΔH rxn = + 55 kJ/mol, for the forward reaction means that the reaction is endothermic, i.e. the reactants absorb energy and the products are higher in energy.
Activation energy is the difference in the energy level of the reactants and the peak in the potential energy diagram (the energy of the transition state).
For an endothermic reaction, the products will be closer in energy to the transition state than what the reactans will be; so, the activation energy of the reversed reaction is lower than the activation energy of the forward reaction.
Activation energy of reverse and forward reactions is related by:
Activation energy of reverse rxn = Activation energy of forward rxn - ΔH rxn
=> Activiation energy of reverse rxn = 102 kJ/mol - 55 kJ/mol = 47 kJ/mol
Answer: 47 kJ/mol
The blank is filled by Na₂SO₄, and the complete equation for the double displacement reaction is:
Na₂SO₄ + BaCl₂ = BaSO₄ + 2 NaCl
<h3>What is a double displacement reaction?</h3>
It is a reaction in which both reactants exchange anions and cations.
Let's consider the following incomplete double displacement reaction.
_____ + BaCl₂ = BaSO₄ + 2 NaCl
If we compare the left and right sides, we can see that the missing ions in the left side are Na⁺ and SO₄²⁻. Thus, the missing compound is Na₂SO₄. The complete equation is:
Na₂SO₄ + BaCl₂ = BaSO₄ + 2 NaCl
Learn more about double displacement here: brainly.com/question/23918356
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