Convert 80ug/m^3 of SO2 at temperature of 25C and 101.325 kPa pressure.
the density of air at STP is 1.29 g/L
http://www.google.com/#sclient=psy&hl=en&rlz=1R2GF...
at 25 Celsius, the volume will exand, & it will become less dense by a ratio of T1 / T2 (Charles' law):
1.29 g/L @ 273 Celsius / 298 Celsius = 1.18 grams /Litre
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the cubic meter of air in your 80ug/m^3 has a mass of approximately:
1000 litres @ 1.18 g/L = 1180 grams
find grams of SO3 / gram of air:
(80 e-6 grams SO3) / (1180 g air) = 6.78 e-8 g SO3 per gram of air
find the ppm by mass:
(6.78 e-8 g SO3 per gram of air) (1 e6) = 6.78 e-2
your answer, rounded to 2 sig figs is
0.068 ppm SO3 in air , by mass
the " 80ug/m^3" has only 1 sig fig showing,
you might be expected to round your answer off to
0.07 ppm
0.0678 gra
Comments
the density of air at STP is 1.29 g/L
http://www.google.com/#sclient=psy&hl=en&rlz=1R2GF...
at 25 Celsius, the volume will exand, & it will become less dense by a ratio of T1 / T2 (Charles' law):
1.29 g/L @ 273 Celsius / 298 Celsius = 1.18 grams /Litre
===============================================================
the cubic meter of air in your 80ug/m^3 has a mass of approximately:
1000 litres @ 1.18 g/L = 1180 grams
find grams of SO3 / gram of air:
(80 e-6 grams SO3) / (1180 g air) = 6.78 e-8 g SO3 per gram of air
find the ppm by mass:
(6.78 e-8 g SO3 per gram of air) (1 e6) = 6.78 e-2
your answer, rounded to 2 sig figs is
0.068 ppm SO3 in air , by mass
the " 80ug/m^3" has only 1 sig fig showing,
you might be expected to round your answer off to
0.07 ppm
0.0678 gra