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19 Cards in this Set
- Front
- Back
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How do you express mathematically he mixing ratio? |
Mixing ratio= Concentrtaion i/ Total concentration |
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What can be a good analogy of the mixing ratio? |
Partial pressures ; Pi/Ptotal |
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What is the most common unit for the mixing ratio? |
Parts per "ppm,ppb, ppt) |
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Why are "ppm, ppb, ppt" a relevant measure at times? |
These ratios are independent of density which changes according to altitude. |
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What is the PEL and IDLH rates? |
PEL: Permissible exposure limit to air polution IDLH: Immediately dangerous to life or health quantity of air polution |
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How can you find a gas concentration in the air knowing only its ppm? |
using the amount of molecules of the gas, use PV=nRT -> concentrtaion= n/V=Partial pressure/RT |
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How can you convert 8 Mol/L in molecules per centimeter? |
8 mol/L* 1L/1000ml* 1ml/1cm * 6.022*10^23 molecules/mol |
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What is the relative Humidity? How do you express it mathematically? |
It is the partial pressure of water vapor compared to a saturated vapor atmosphere condition. It is expressed as followed: PH2O/P0H2O*100% |
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What is the notion of partial pressure? |
It is the relative contribution of each gas to a total pressure. Pressure is additive between each gas composing the atmosphere. |
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What is another word for saturation vapour pressure? WHat is it? |
Vapour pressure It is the partial pressure of the liquid saturated vapour if in a closed environment. |
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What does the saturation vapour pressure strongly depends on ? Show the mathematical relationship. |
Temperature: PH2O=4/3*(20.386-5132/T) |
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it terms of vapour pressure, how can you explain the boiling point of a compound? |
Since temperature affects the vapour pressure, the boiling point of a compound is the point where the vapor pressure is equal to the atmospheric pressure, hence boiling the compound |
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What happens if the partial pressure of a gas is greater than it's vapour pressure? |
The excess pressure will often condense to a liquid However you need a condensation nuclei. If not present you will have a supersaturated vapour. |
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What does isobaric mean? |
Constant pressure |
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What is the dew point? |
The temperature at which a parcel of air becomes saturated under isobaric condition. |
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Why do you bother with the dew point? |
The problem with relative humidity is that you need to know the temperature to better understand what it means. 99% humidity at cold temperature can be quite dry. |
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How would you find an approximation of the dew point knowing the temperature and Relative humidity? |
1: Find Pressure P0H2O 2: Find PH2O using RH and answer in 1 3: Find Dew point using inverse of Vapour pressure function. |
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What is the main phenomenon that allows us to understand cloud formation? |
The dew point |
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How do clouds form? |
A given parcel of air rises in the atmosphere. By doing so it expands and cools of. Eventually it will reach the dew point temperature of water, If a condensation nuclei is present ( small particles) water will condense on them and clouds will form. |
