A chemical system within a sealed 1 L reaction vessel is described by the following reversible reaction equation:
2H2S(g) <-->2H2(g) + S2(g)
If the equilibrium constant is 0.000 004 200 at 1103 K find:
the reaction quotient initially.
This makes no sense to me. Reaction quotients are determined by substituting non-equilibrium concns. With a Keq of 4.2E-6 (I assume that is what you meant) we can calculate the equilibrium concns of the three species. I don't see any numbers with which to calculate Qrxn.
how I would answer this is to say that though we cannot determine the amount of moles, we can make a few assumptions, primarily that because it is the initial reaction the products have not been formed and the reaction consists of only reactants. As such our Qc equation will have a value of 0 which is valid as it is not a negative value.
To find the reaction quotient initially, we need to determine the concentrations of the species involved in the reaction and use their values to calculate the reaction quotient.
Since the reaction is taking place in a sealed reaction vessel, we can assume that the initial number of moles of each species is zero. Therefore, the initial concentrations of H2S, H2, and S2 are all zero.
The reaction quotient, Q, is calculated using the concentrations (or partial pressures) of the reactants and products at any given time, using the same format as the equilibrium constant expression. In this case, the reaction quotient is given by:
Q = [H2]²[S2] / [H2S]²
Since the initial concentrations are zero, we have:
Q = (0)² / (0)² = 0
So, the reaction quotient initially is 0.