Unit 5 - Gases and Atmospheric Chemistry Flashcards
(31 cards)
What is kinetic molecular theory?
the entities in solids, liquids, and gases are in constant, random motion
How do entities move?
translational motion, rotational motion, and vibrational motion
Strong attractions between particles limit motion
What is kinetic energy?
energy possessed by a moving object
What is temperature?
a measure of the average kinetic energy of the entities in a substance
What happens when a substance is warmed?
When a substance is warmed, the kinetic energy of its entities increase, resulting in more rapid motion. Eventually, the attractive forces
between particles are broken, allowing them to flow past each
other (i.e., a change of state)
What is the earth’s atmosphere?
a thin blanket of moisture and gases that protects us from the hostile environment of outer space (troposphere, stratosphere, mesosphere, thermosphere)
Patterns in the earth atmosphere:
- air molecules are pushed together by the atmosphere above them
- As you move further above sea level, air density decreases and consequently, oxygen concentration also decreases
- Air density decreases as altitude increases since there is “less” atmosphere pushing down on the air molecules
Atmospheric composition:
- he troposphere and stratosphere have the biggest influence on us due to their proximity
- N2(g) and O2(g) are the most abundant in these layers
- Nitrogen found in proteins and DNA
- Nitrogen-fixing bacteria convert N2(g) into soluble nitrates that
plants can absorb - N2(g) is released back into the atmosphere through decaying
plants and animals and their wastes
Oxygen and other gases in the atmosphere:
- Oxygen in the atmosphere is found in the form O2(g) and O3(g) (ozone) –> Ozone acts as a radiation shield by absorbing UV light from the sun, and preventing excessive
- UV radiation from reaching Earth’s surface
- Other gases in the atmosphere include argon, water vapour (99% is in the troposphere), and carbon dioxide
a) Carbon dioxide is required for photosynthesis
b) CO2(g) returned through cellular respiration
What is the Greenhouse affect?
a natural process whereby gases and clouds absorb infrared (IR) radiation emitted from Earth’s surface and radiate it, heating the atmosphere and Earth’s surface
- When GHG absorb specific frequencies of IR radiation, they vibrate and re-radiate this energy back to Earth where it warms the ground (i.e., IR radiation is trapped within the atmosphere)
What are air pollutants?
- Photochemical smog: is a hazy cloud of gases and air pollutants formed by the reaction of emissions of factories and vehicles with sunlight
- Particulate matter is the mixture of very small solid and liquid particles found in the atmosphere
a) Particulate matter can damage the respiratory system when inhaled into the lungs, reduce visibility, and interrupt air travel (e.g., volcanic eruption)
What are chemical pollutants?
- Particulate matter can be released indoors from printers, fireplaces, wood-burning stoves, candles, etc.
- Off-gassing: is the release of one or more gases from a substance at room temperature
- Methanal: a VOC, is a colourless, flammable gas often found in preservative and embalming fluid
a) Commonly found in low amounts in our indoor air from pressed wood products, paints, certain paper products, and fabrics - Carbon monoxide is a colourless, odourless, tasteless gas (at room temperature) that binds to hemoglobin and blocks it from carrying oxygen to our tissues
a) CO poisoning: headache, dizziness, weakness, nausea and vomiting, shortness of breath, …
What are biological pollutants?
- Dust mites: live in warm, humid environments (e.g., linens, mattresses, pillows, carpets), feed on shed skin
cells, and their wastes are the most common household allergen - Mould refers to various species of fungi that grow indoors and their spores can cause respiratory difficulties, skin rashes, or other allergic reactions
What are atmospheric pressure?
The force per unit area exerted by air on all objects (SP, STP, SATP)
- As pressure increases, gas density decreases –> closer to the earth
- At higher altitudes, the atmospheric pressure is less than the air in your middle ear
- Volume of air in the middle ear expands and presses the eardrum out
Why do your ears pop in high altitude?
due to the different pressure inside the middle ear and the atmosphere
What is Charle’s law?
States that the volume of a gas is directly proportional to its temp (in kelvins) if the pressure and amount of gas is constant
What is Boyle’s law?
States that the volume of a gas is inversely proportional to its pressure, if the temp and amount of gas are constant
What is the Gay-Lussac’s Law?
States that the pressure of a gas is directly proportional to its temp, in Kelvins, if the volume and amount of gas is constant
In molecular theory, if temp increases, kinetic energy increases, with greater kinetic energy, molecules tend to coilide and causes pressure to increase
What is the combined gas law used for?
Dealing with calculations involving changes in volume, temp, or pressure for a fixed amount of gas
What is the law of combining volume?
When volume of gaseous reactants and products of chemical relations are always in simple ratios of whole numbers (temp and pressure must be constant)
What are the pattern’s in avo’s law?
- Since the temperature of both gases is the same, the kinetic energy of both samples is the same
- In order for the pressure (number of collisions) to be equal, the number of particles must be the same
- If the number of entities is the same, then the number of moles is also the same
What is avo’s law?
The volume of a gas is directly proportional to the amount (n) of the gas at the constant temp and pressure
What is the molar volume?
The volume occupied by one mole of a gas at a specified temp and pressure
- STP: 22.4 L
- SATP:24.8 L
What is ideal gas?
All gas laws are based on the assumption that the gas behave “ideally”
Properties:
- They move in straight lines, but in random directions
- No kinetic energy is lost when ideal gases collide (i.e., collisions are perfectly elastic)
- The volume of an ideal gas is insignificant (zero) compared to the volume of the container
- There are no attractive or repulsive forces between gas molecules
- They do not condense to liquids when cooled
