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Homework Help: Unit conversion of ppm

  1. Oct 2, 2015 #1
    1. The problem statement, all variables and given/known data
    The air near a water heater in the basement of an old home is measured for carbon monoxide (CO) and found to contain 0.1% by volume CO at 22*C and 1 atm. Express the CO concentration in the basement in micro-gram/m^3 .
    2. Relevant equations
    P = absolute pressure (atm); V = volume (m3 ); n = mass (mole); R = ideal gas constant = 0.082056 L atm K−1 mol−1 ; and T = absolute temperature (K).

    3. The attempt at a solution
    The answer said that 0.1% = 10^−3 ppm = 10^3 L CO/ 10^6 L air. But in the book it also has equation to express that {% by volume} x 10000 =ppm. I don't know which one is correct and how to use them.

    Beside, after I have calculated the gram of CO, how to relate it with the micro-gram/m^3 ?
    thank you.
  2. jcsd
  3. Oct 2, 2015 #2


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    Staff Emeritus
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    Homework Helper

    There's a typo here, either from your text book or introduced by copying from it.

    1 ppm = 1 / 106

    0.1% = 103 ppm = 1000 ppm, which is the same as saying that 0.1% CO by volume = 1000 L of CO in 106 L of air

    If 0.1% = 1000 ppm, then how many ppm is 1% ?

    Take 1 m3 of air at 22°C and P = 1 atm. How many μg of CO are in that cubic meter if the concentration is 0.1% by volume?
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