Question

If 20.00 mol of hydrogen gas completely reacted with 20.00 mol of chlorine gas

at constant pressure, releasing 3700 kJ of heat, which of the following
thermochemical equations is correct?
H2(g) + Cl2(g) => 2HCl (g); AH° = -185 kJ
H2(8) + Cl2(8) => 2HCl (g); AH° = +185 kJ
H2(g) + Cl2(g) => 2HCl (g); AH° = +370 kJ
H2(g) + Cl2(g) => 2HCl (g); AH° = -3700 kJ
H2(g) + Cl2(g) => 2HCl (g); AH° = -1850 kJ

Answer 1

The correct thermochemical equation is H2(g) + Cl2(g) => 2HCl(g); AH° = -185 kJ

Step-by-step explanation:

The correct thermochemical equation for the reaction between 20.00 mol of hydrogen gas (H2) and 20.00 mol of chlorine gas (Cl2) at constant pressure, releasing 3700 kJ of heat, is:

H2(g) + Cl2(g) => 2HCl(g); AH° = -185 kJ

This equation represents the formation of 2 moles of hydrogen chloride (HCl) from 1 mole of hydrogen gas (H2) and 1 mole of chlorine gas (Cl2), while releasing 185 kJ of heat.