What is the partial pressure of oxygen at s.t.p. in a gaseous mixture containing 100...
CHEMISTRY
WAEC 2022
What is the partial pressure of oxygen at s.t.p. in a gaseous mixture containing 100 cm3 of oxygen and 900 cm3 of nitrogen gas?
- A. 1.0 atm
- B. 0.1 atm
- C. 9.0 atm
- D. 0.9 atm
Correct Answer: B. 0.1 atm
Explanation
Partial pressure is found by Dalton's Law: Px = PTotal ( nx / nTotal ) where Px = partial pressure of gas x PTotal = total pressure of all gases nx = number of moles of gas x nTotal = number of moles of all gases
Step 1 Find PTotal Standard pressure is 1 atm.
Step 2 Add up the number of moles of the component gases to find nTotal nTotal = noxygen + nnitrogen nTotal = 100 + 900 nTotal =1000cm3
Step 3 Now you have all the information needed to plug the values into the equation and solve for Poxygen P-oxygen = PTotal ( n-oxygen / nTotal ) oxygen = 1 atm ( 100 / 1000 ) oxygen= 0.1atm
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