In this reaction, how does the rate of forward reaction vary with the concentration of the product?

2H2S (g) ⇌ 2H2 (g) + S2 (g)

Based on Le Chatelier's principle, if the equilibrium of a system is disturbed by changing the temperature, pressure or concentration of the system, then it will shift in a direction to undo the effect of the induced change.

The given equilibrium is:

2H2S (g) ↔ 2H2 (g) + S2 (g)

Rate = (-1/2) d[H2S]/dt = 1/2 d[H2]/dt = d[S2]/dt

If the concentration of the products is increased then the rate of forward reaction will decrease

If the concentration of the products is decreased then the rate of forward reaction will increase