In the first reaction, solid carbon (in the form of graphite) reacts with gaseous oxygen to produce gaseous carbon dioxide. The enthalpy change for this reaction is -393.5 kJ/mol, which means that the reaction is exothermic (it releases heat).
In the second reaction, gaseous hydrogen reacts with gaseous oxygen to produce liquid water. The enthalpy change for this reaction is -285.8 kJ/mol, which means that the reaction is also exothermic (it releases heat).
In the third reaction, gaseous methane (CH4) reacts with gaseous oxygen to produce gaseous carbon dioxide and liquid water. The enthalpy change for this reaction is -890.3 kJ/mol, which means that the reaction is also exothermic (it releases heat).
These enthalpy changes represent the amount of heat released or absorbed during each of these reactions, per mole of reactant consumed.
Answers & Comments
Answer:
The given equations and values represent the enthalpy changes for the following reactions:
1. C(graphite) + O2(g) -> CO2(g) ΔH° = -393.5 kJ/mol
2. H2(g) + 1/2O2(g) -> H2O(l) ΔH° = -285.8 kJ/mol
3. CH4(g) + 2O2(g) -> CO2(g) + 2H2O(l) ΔH° = -890.3 kJ/mol
In the first reaction, solid carbon (in the form of graphite) reacts with gaseous oxygen to produce gaseous carbon dioxide. The enthalpy change for this reaction is -393.5 kJ/mol, which means that the reaction is exothermic (it releases heat).
In the second reaction, gaseous hydrogen reacts with gaseous oxygen to produce liquid water. The enthalpy change for this reaction is -285.8 kJ/mol, which means that the reaction is also exothermic (it releases heat).
In the third reaction, gaseous methane (CH4) reacts with gaseous oxygen to produce gaseous carbon dioxide and liquid water. The enthalpy change for this reaction is -890.3 kJ/mol, which means that the reaction is also exothermic (it releases heat).
These enthalpy changes represent the amount of heat released or absorbed during each of these reactions, per mole of reactant consumed.