Units Of Measurement Flashcards
International system of units (SI)
Meters, kilos, degrees Celsius
American units
Feet, pounds, degrees Fahrenheit
1 m =
100 cm = 10^3 mm = 10^6 μm
1 g =
10^3 mg = 10^6 μg
1 m^3 =
1000 L
A waste water effluent of 1000 L/hr contains 6 μg/L. What is the mass in g of mercury discharged per day?
(6 μg/L) x (1 mg/1000 μg) x (1g/1000mg) = 6x10^-6 g/L
(6x10^-6 g/L) x (1000 L /hr) x (24 hr/ day) = 0.144 g/day
1 mg/L =
1 ppm
1 μg/L =
1 ppb
Concentration units for gases
1) volumetric terms (ppmv)
2) percent by volume (%)
3) mass per unit volume (mg/m^3, μg/m^3)
Conversion for gases between ppmv & percent by volume (%)
1 ppmv= 10^-4 %
Express 0.8 ppmv as percent by volume (%)
1 ppmv/ 10^-4 = 0.8 ppmv/ X,
X= 0.8 x 10^-4 %
Converting btw ppmv & mg/m^3 for gases
Mg/m^3 = ((mol weight x ppmv)/ 22.414) x (273.15/actual temp) x (actual pressure/1 ATM)
Standard temperature and pressure (STP):
0 degrees Celsius & 1atm
Convert the concentration of ozone (O3) at 0.08 ppmv to mg/m^3, at 25C, 1atm, mol weight of O3 = 48 g/mol
Mg/m^3= ((48 x 0.08)/22.414) x (273.15/273.15 +25) x (1atm/1atm)
=0.157 mg/m^3
The Idea Gas Law: PV = nRT
P: pressure (ATM) V: volume (L) n: mass (mol) R: ideal gas constant (0.082056 L x ATM x K^-1 x mol^-1) T: temperature (K)