Chapter 10, Problem 103IL

Many nitrate salts can be decomposed by heating. For example, blue, anhydrous copper(II) nitrate produces the gases nitrogen dioxide and oxygen when heated. In the laboratory, you find that a sample of this salt produced a 0.195-g mixture of gaseous NO₂ and O₂ with a total pressure of 725 mm Hg at 35 °C in a 125-mL flask (and black, solid CuO was left as a residue). What is the average molar mass of the gas mixture? What are the mole fractions of NO₂ and O₂ in the mixture? What amount of each gas b in the mixture? Do these amounts reflect the relative amounts of NO₂ and O₂ expected based on the balanced equation? Is it possible that the fact that some NO₂ molecules combine to give N₂O₄ plays a role?

Heating copper(II) nitrate produces nitrogen dioxide and oxygen gas and leaves a residue of copper(ll) oxide.