Answer:
The heat of reaction when hydrogen and oxygen combine to form water is :
<u>C. 571.6 kJ</u>
Explanation:
Enthalpy Change = The enthalpy change for the formation of 1 mole of the substance from their standard state is called the enthalpy of formation.
This is intensive quantity as it is fixed for 1 mole .
Intensive properties = Those properties which are independent on the amount of the substance are intensive properties.
The value of these quantities does not get halve if you divide the substance into two equal parts. example , density, refractive index.
However , the enthalpy of reaction is extensive. Because on increasing the amount the value of the enthalpy also get doubles
Hence for this reaction :

Its value is -285.8 kJ for 1 mole
And here two moles are present . so the value of molar enthalpy is:
-285.8 x 2 = -571.6 kJ
Thunderstorms between Tampa and titusville
Answer:
II. The reaction is exothermic.
III. The enthalpy term would be different if the water formed was gaseous.
Explanation:
For the reaction:
C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l)
The ΔH is -1.37×10³ kJ. As the change in enthalpy is <0,<em> II. The reaction is exothermic.</em>
The ΔH formation of a compound is different if the chemical is in liquid or gaseous phase. For that reason: <em>III. The enthalpy term would be different if the water formed was gaseous.</em>
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I hope it helps!