Question

A chemical reaction has Hf,reactants = –1,023 kJ and Hf,products = –935.3 kJ. Which graph can be used to represent this reaction pathway?

Answer 1

Hey there!

The pathway will resemble a hill , The minimum amount of energy the reagents need to make the complex activated, is the activation energy , The difference in heights of the products and reactants will be equivalent to the difference in energies.:

ΔH = ( -1,023 kj ) - ( - 935,3 kj )

ΔH = -87.7 Kj

Answer 2

Answer: $\Delta H$ = 87.7 kJ

Explanation: Reactants required a minimum amount of energy to give the products. This minimum amount of energy required is known as activation energy which is the energy difference between activated complex and the reactants.

Enthalpy of reaction is the products energy minus reactants energy.

$\Delta H$ = Energy of products - energy of reactants

From given information, Hf of reactants is -1023 kJ and the Hf of products is -935.3 kJ.

So,  $\Delta H$ = -953.3 kJ - (-1023 kJ)  

= -953.3 kJ + 1023 kJ

= 87.7 kJ

Sign of $\Delta H$ is positive that indicates an endothermic reaction.

It is also clear from the given Hf values of reactants and products. Hf value of reactants is less than products which indicates an endothermic reaction.