Ammonia will decompose into nitrogen and hydrogen at high temperature. An industrial chemist studying this reaction fills a 200. mL flask with 4.6 atm of ammonia gas, and when the mixture has come to equilibrium measures the amount of nitrogen gas to be 0.69 atm. Calculate the pressure equilibrium constant for the decomposition of ammonia at the final temperature of the mixture. Round your answer to 2 significant digits.

Tooth enamel consists mainly of the mineral calcium hydroxyapatite, ca_10(po_4)_6(oh)_2. trace elements in teeth of archaeological specimens provide anthropologist with clues about diet and diseases of ancient people. students at hamline university measured strontium in enamel from extracted wisdom teeth by atomic absorption spectroscopy. solutions with a constant total volume of 10.0 ml contained 0.726 mg of dissolved tooth enamel plus variable concentrations of added sr. added sr find the concentration of sr in the 10 ml sample solution in parts per billion = ng/ml. find the concentration of sr in tooth enamel in parts per million = mu g/g.