Calculate the DHof for the following reaction under standard state conditions:
2 Ag2S(s) + 2 H2O(l) ---> 4 Ag(s) + 2 H2S(g) + O2(g)
Given the following information:
Ag2S(s) ÄHof = -32.6 kJ/mol
H2O(l) Ä Hof = -285.83 kJ/mol
H2S(g) ÄHof = -20.6 kJ/mol
To calculate the standard enthalpy change (ΔHof) for the given reaction, you need to consider the enthalpy changes for each reactant and product.
First, let's calculate the enthalpy change for the reactants:
ΔH1 = (2 mol Ag2S) * (-32.6 kJ/mol)
= -65.2 kJ/mol
ΔH2 = (2 mol H2O) * (-285.83 kJ/mol)
= -571.66 kJ/mol
Next, let's calculate the enthalpy change for the products:
ΔH3 = (4 mol Ag) * (0 kJ/mol)
= 0 kJ/mol
ΔH4 = (2 mol H2S) * (-20.6 kJ/mol)
= -41.2 kJ/mol
ΔH5 = (1 mol O2) * (0 kJ/mol)
= 0 kJ/mol
Now, we can calculate the overall enthalpy change for the reaction by summing the individual enthalpy changes for the reactants and products:
ΔHof = (ΔH3 + ΔH4 + ΔH5) - (ΔH1 + ΔH2)
= (0 kJ/mol + (-41.2 kJ/mol) + 0 kJ/mol) - (-65.2 kJ/mol + (-571.66 kJ/mol))
= (-41.2 kJ/mol) + (65.2 kJ/mol + 571.66 kJ/mol)
= -41.2 kJ/mol + 636.86 kJ/mol
= 595.66 kJ/mol
Therefore, the ΔHof for the given reaction under standard state conditions is 595.66 kJ/mol.
To calculate the ΔHof (standard enthalpy of formation) for the given reaction, you need to sum up the enthalpies of formation for the products and subtract the sum of the enthalpies of formation for the reactants. The ΔHof for the reaction can be calculated using the equation:
ΔHof = Σ ΔHof(products) - Σ ΔHof(reactants)
Let's calculate the ΔHof for the reaction step by step:
Given:
ΔHof(Ag2S(s)) = -32.6 kJ/mol
ΔHof(H2O(l)) = -285.83 kJ/mol
ΔHof(H2S(g)) = -20.6 kJ/mol
Reactants:
2 Ag2S(s) + 2 H2O(l)
Products:
4 Ag(s) + 2 H2S(g) + O2(g)
Calculating the ΔHof for reactants (sum of enthalpies of formation for reactants):
Σ ΔHof(reactants) = 2 × ΔHof(Ag2S(s)) + 2 × ΔHof(H2O(l))
= 2 × (-32.6 kJ/mol) + 2 × (-285.83 kJ/mol)
Calculating the ΔHof for products (sum of enthalpies of formation for products):
Σ ΔHof(products) = 4 × ΔHof(Ag(s)) + 2 × ΔHof(H2S(g)) + ΔHof(O2(g))
= 4 × 0 kJ/mol + 2 × (-20.6 kJ/mol) + 0 kJ/mol
Substituting the values into the equation:
ΔHof = Σ ΔHof(products) - Σ ΔHof(reactants)
= (4 × 0 kJ/mol + 2 × (-20.6 kJ/mol) + 0 kJ/mol) - (2 × (-32.6 kJ/mol) + 2 × (-285.83 kJ/mol))
Now, you can calculate the value of ΔHof.