Calculate the equilibrium constant kc she obtained for this

Question

A student ran the following reaction in the laboratory at 529 K:

COCl₂(g) <-----> CO(g) + Cl₂(g)

When she introduced 1.76 moles of COCl₂(g) into a 1.00 liter container, she found the equilibrium concentration of COCl₂(g) to be 1.72 M.  

Calculate the equilibrium constant, K_c, she obtained for this reaction.  

K_c = __________