Amixture of so2(g) and o2(g), formed by the complete decomposition of so3(g), is collected over water at 34°c at a total pressure of 760 mmhg. if the vapor pressure of water is 40 mmhg at 34°c, what is the partial pressure of so2?

The decomposition of so3 to so2 gas and o2 gas can be described in the balanced chemical equation: 

2so3(g) = 2 so2 (g) + 02(g). 

so assuming a complete reaction, the ratio of so2 gas to total products is 2/3 while that of 02 is 1/3. 

Subtracting water's water vapor pressure, 760-40 mm hG = 720 mm Hg.

then the products partial pressures are

so2 = 2/3 * (720) = 480 mm Hg.
o2 = 720-480 = 240 mm Hg.

What is the question

It is a mixture. simply put, a compound must be pure, that is, of only one chemical structure and composition. a mixture is made of different chemical substances (i.e. elements, molecules, compounds) that are not chemically bonded to each other, but instead physically grouped together, as in the case of gasoline (a homogeneous solution).