Final answer:
To calculate the mass of hydrogen sulfide needed for a reaction releasing 1025 kJ, the moles of hydrogen sulfide were found by dividing 1025 kJ by the energy released per mole (204 kJ/mol), yielding 5 moles. Multiplying this by the molar mass of hydrogen sulfide gives a mass of 170.4 grams.
Step-by-step explanation:
The student's question involves determining the mass of hydrogen sulfide (H₂S) required for a reaction that releases 1025 kJ of energy, given that the reaction of gaseous hydrogen sulfide with oxygen produces sulfurous acid and releases 204 kJ per mole of hydrogen sulfide. To answer this, we will use stoichiometry and enthalpy concepts. Since 204 kJ is released per mole of H₂S, to calculate the moles of H₂S that would release 1025 kJ, we perform the following calculation:
Moles of H₂S = 1025 kJ / 204 kJ/mol = 5 moles
Knowing the molar mass of H₂S, which is approximately 34.08 g/mol, we can calculate the mass:
Mass of H₂S = 5 moles × 34.08 g/mol = 170.4 g
Therefore, the mass of hydrogen sulfide needed for a reaction that releases 1025 kJ of energy is 170.4 grams.