For the reaction: n2(g) + 3h2(g)⇔ 2nh3(g), at a particular temperature, the concentrations of n2, h2 and nh3 are 2.1 x 10–3 m, 3.2 x 10–2 m, and 1.8 x 10–1 m, respectively. calculate a value of k for this reaction