The sulphide capacity (C_s) of liquid slag of composition 55 wt% CaO, 20 wt% SiO₂, 15 wt% Al₂ O₃ and 10 wt% MgO is given by the following equation
$$\log {C_s} = 3.44\left( {{X_{caO}} + 0.1\,{X_{MgO}} - 0.8\,{X_{A{l_2}{O_3}}} - {X_{si{o_2}}}} \right) - \left( {\frac{{9894}}{T}} \right) + 2.05$$
where, X is mole fraction of the respective components. Atomic weights of Ca, Mg, Si, Al and O are 40, 24, 28, 27, and 16 respectively. The value of C_s at 1900 K is