A mixture of 1.374 g of H₂ and 70.31 g of Br₂ is heated in a 2.00 L vessel at 700 K . These substances react as follows: H₂(g)+Br₂(g)⇌2HBr(g) At equilibrium the vessel is found to contain 0.566 g of H₂. Calculate the equilibrium concentration of H₂.