Notes nothing to do with rate spontaneous reaction can be slow or fast for instance, diamond to graphite is a very slow yet spontaneous reaction if the forward reaction is spontaneous, the reverse is non- spontaneous. Delta h is not enough to determine spontaneity. S is a measure of disorder gas particles are very spread out. Entropy goes from localized to dispersion for spontaneous reactions. Whereas solid particles are in ordered structures. A) a2 (gas) + 2b (gas) -> 2ab (gas) B) negative s imagine two coins combinations of results are only hh; ht; th; tt therefore 2 to the power of 2 is four imagine three coins combinations of results can be hhh; ttt; hht; hth; tht; tth; More entropy in drop of water than a bucket because entropy is an extensive property. Delta s = s of cao plus s of co2 subtract s of caco3 = 1mol(39. 7j/kmol) + 1mol times 213. 6j/kmol 1 mol times.