Consider the reaction pathway graph below. Which statement best describes this graph?
This is an exothermic reaction with a positive ΔHrxn.
This is an exothermic reaction with a negative ΔHrxn.
This is an endothermic reaction with a positive ΔHrxn.
This is an endothermic reaction with a negative ΔHrxn.

This is an endothermic reaction with a positive ΔHrxn.

Explanation:

From the question given above, we can see clearly that the energy of the product (Hp) is greater than the energy of the reactant (Hr). This simply means that the reaction is endothermic as the enthalpy change (ΔH) for the reaction will be positive.

Enthalpy change (ΔH) = Heat of product (Hp) – Heat of reactant (Hr)

ΔH = Hp – Hr = positive

NOTE: A reaction with positive enthalphy change (ΔH) is termed endothermic reaction.

in 1783 cavendish was working with his hydrogen gas and found that when he burned it and condensed the vapor it was water. this was very significant since it disproved the greek theory of elements completely since water was not a simple substance but the product of two gases. it was lavoisier who hearing of the experiment gave cavendish's gas the name hydrogen ("water-producer") and added that hydrogen burned by combining with oxygen and that water was a hydrogen-oxygen combination.

explanation:

answer: -

reaction:

na + cl ⇌ nacl

balanced chemical equation:

na + 2cl ⇌ nacl2

sodium + clorine goes to form sodium chloride (table salt).

the product is nacl2.

and the reactants are na and cl.

(note: if you don’t know what ⇌ means, read below: -

⇌(double head arrow) means reversible reaction).