Question

Using the provided table and the equation below, determine the heat of formation (in kJ/mol) for PbS. 2 PbS (s) + 3 O2 (g) → 2 SO2 (g) + 2 PbO (s) AH° = -828.4 kJ/mol Substance AHf° (kJ/mol) O2 (9) 0 SO2 (g) -296.9 PbO (s) -217.3

Answer 1

The heat of formation for PbS is -663.9 kJ/mol.

Step-by-step explanation:

To determine the heat of formation for PbS, we can use Hess's law and the given equation. First, we need to identify the elements involved in the reaction and their standard enthalpies of formation. Using the table provided, we can find the AHf for each substance: O2 (g) = 0 kJ/mol, SO2 (g) = -296.9 kJ/mol, PbO (s) = -217.3 kJ/mol.

Next, we can calculate the AHf for PbS using the equation and the AHf values:

• 2 PbS (s) + 3 O2 (g) → 2 SO2 (g) + 2 PbO (s)
• AH° = -828.4 kJ/mol

Using the equation and the given values, we can set up the equation:

2(-217.3 kJ/mol) + 3(0 kJ/mol) = 2(-296.9 kJ/mol) + 2 PbS (s)

Simplifying the equation, we find that the AHf for PbS is -663.9 kJ/mol.

Answer 2

To determine the heat of formation for PbS, we can use Hess's Law and the given equation. The heat of formation for PbS is -414.2 kJ/mol.

Step-by-step explanation:

To determine the heat of formation for PbS, we can use Hess's Law and the given equation. The equation shows the formation of PbS from its elements Pb(s) and S(s). The standard heat of formation for elements is always zero, so we can use the given values for PbO(s) and SO2(g) to find the heat of formation for PbS.

The given equation is:

2 PbS (s) + 3 O2 (g) → 2 SO2 (g) + 2 PbO (s) AH° = -828.4 kJ/mol

From this equation, we can see that the formation of 2 moles of PbO(s) releases -828.4 kJ of heat. Therefore, the formation of 1 mole of PbO(s) releases -414.2 kJ of heat. Since PbS is formed from 1 mole of PbO(s), the heat of formation for PbS is also -414.2 kJ/mol.