The concentration of ozone in los angeles is 0.67 ppm on a summer day. what is the partial pressure of o3 if the total pressure is 735 torr?

We use the Raoult's Law to answer this question.

Partial Pressure = Mole Fraction*Total Pressure

When concentration is expressed in ppm, it means 'parts per million'. So, there can be 0.67 mol of ozone per 10⁶ mol of mixture.

Mole fraction = 0.67/10⁶ = 0.67*10⁻⁶

Partial pressure = 0.67*10⁻⁶ (735 torr) = 4.92*10⁻⁴ torr