For which of the following reactions at a given temperature T , is the difference between enthalpy change and internal energy change equal to -RT ?

Step-by-step solution

The relationship between enthalpy change ( H ) and internal energy change ( U ) is given by: H = U + n_g RT H - U = n_g RT Given that H - U = -RT , we have: n_g RT = -RT n_g = -1 Now, let us calculate n_g (moles of gaseous products - moles of gaseous reactants) for each option: PCl ₅( g ) PCl ₃( g ) + Cl ₂( g ) : n_g = (1 + 1) - 1 = +1 2 CO ( g ) + O ₂( g ) 2 CO ₂( g ) : n_g = 2 - (2 + 1) = -1 N ₂( g ) + 3 H ₂( g ) 2 NH ₃( g ) : n_g = 2 - (1 + 3) = -2 H ₂( g ) + I ₂( g ) 2 HI ( g ) : n_g = 2 - (1 + 1) = 0 Thus, the