Calculate the Delta Hf of the OH- ion given that the Delta Hf (H2O) = -285.8 kJ mol-1.
Calculate Delta hf for
C2H2(g) + O2(g) --> CO2(g) + H2O(g)
SO2 (g) + O2(g) --> SO3(g)
Fe2O3(s) + Al(s)(g) --> Fe(s) + Al2O3 (s)
To calculate the enthalpy of formation (ΔHf) of the OH- ion, you need to consider the balanced equation of the reaction that forms OH- from its constituent elements. In this case, the equation would be:
H2(g) + 1/2O2(g) → H2O(l)
The enthalpy change for this reaction can be related to the enthalpy of formation of H2O (ΔHf(H2O)).
The reaction shown above is the formation of water from its constituent elements, and it is given that ΔHf(H2O) = -285.8 kJ/mol.
To calculate the ΔHf of the OH- ion, you should consider the fact that OH- is obtained by removing a proton (H+) from H2O. This process can be represented as:
H2O(l) → OH-(aq) + H+(aq)
Since ΔHf is the enthalpy change when one mole of a substance is formed from its elements in their standard states, the ΔHf of the OH- ion is equal in magnitude but opposite in sign to that of H2O.
Thus, the ΔHf of the OH- ion can be calculated as:
ΔHf(OH-) = -ΔHf(H2O)
= -(-285.8 kJ/mol)
= 285.8 kJ/mol
Therefore, the ΔHf of the OH- ion is 285.8 kJ/mol.