When a sample of HI(g) (5.825 mol) is placed in 320.0 L reaction vessel at 702.0 K and allowed to come to equilibrium the mixture contains 1.052 mol of H2(g). What is the equilibrium concentration (mol/L) of HI(g)?

2HI(g) = H2(g)+I2(g)

Set up an ICE chart and go from there.