Ammonia reacts with oxygen according to the equation 4NH3(g)+5O2(g)→4NO(g)+6H2O(g),ΔHrxn =−906 kJ

Calculate the heat (in kJ) associated with the complete reaction of 155 g of NH3. For this problem, be sure to include the correct sign for q to indicate the direction of heat flow.

In a laboratory, 1.55mg of an organic compound containing carbon, hydrogen, and oxygen is burned for analysis. this combustion resulted in the formation of 1.45mg of carbon dioxide and .89 mg of water. what is the empirical formula for this compound?

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.

How many moles of no2 will form when 3.3 moles of cu are reacted with excess hno3?