Test 4 – Chemistry Test Answers – Flashcards

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question
What uniformly fill any container, are easily compressed, and mix completely with like substances?
answer
gases
question
Earth's atmosphere is about what percent of nitrogen?
answer
78%
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Earth's atmosphere is about what percentage of oxygen gas?
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21%
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The universes about what percent of hydrogen gas?
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75%
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What results from the weight of the air (mass of air is being pulled toward the center of earth by gravity)?
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atmospheric pressure
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Who invented the barometer in 1643?
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Evangelista Torricelli
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device used to measure atmospheric pressure
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barometer
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What corresponds to bad weather?
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low atmospheric pressure
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What is atmospheric pressure at sea level?
answer
760mmHg
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What is the atmospheric pressure in higher elevations (such as Breckenridge, Colorado)?
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520mmHg (thin air)
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1atm=
answer
760mmHg
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760mmHg=
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760torr
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760torr=
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1atm
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force/area
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pressure
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what is measured in Newtons?
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pressure
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What is is measured in square meters?
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area
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What is one N/m^2?
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Pascal
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What is the Pascal the SI unit for?
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unit for pressure
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How many Pascals are in one atmosphere?
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101325
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How many inches of Hg are in one atm?
answer
29.92
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How many pounds per square inch are in one atm?
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14.7
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What is Boyle's Law?
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P1V1=P2V2
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What are gases that obey the gas laws termed?
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ideal gases
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What make gases deviate from ideal gas behavior?
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high pressure and low temperature (makes them closer together)
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Who was the first to fill a balloon with hydrogen gas and first to make a solo balloon flight?
answer
Jacques Charles
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What is Charles' Law?
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V1/T1=V2/T2
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The volumes of all gases extrapolate to what?
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0K or -273.15C
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What is Avogadro's Law?
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V1/n1=V2/n2
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What is the ideal gas law?
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Pv=nRT
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Pressure units
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atm
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volume units
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liters
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temp units
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Kelvin
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What is the molar volume of one mole of a gas at STP?
answer
22.4L
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What is the molar mass formula?
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dRT/P
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for a mixture of gases in a container, the total pressure exerted is the sum of the pressures that each gas in a mixture of gases in a container depends on the number of moles of that gas
answer
Dalton's Law of Partial Pressure
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What is made from sodium azide?
answer
airbags
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balance the decomposition of sodium azide
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2NaN3->2Na+3N2
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What do laws do?
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summarize observed behavior
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What do theories do?
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explain why
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When are models considered successful?
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if i explains the observed behavior in question and predicts correctly the result of future experiments
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Why is the volume of an individual particle assumed to be zero?
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particles are so small compared with distances between them
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What are the causes of pressure exerted by the gas?
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particles are in constant motion so collisions of the particles with walls are the causes
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particles are assumed to exert nor forces on each other
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they are assumed neither to attract nor repel each other
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What is assumed to be directly proportional to the Kelvin temp of the gas (ideal not real)
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average kinetic energy of a collection of gas particles
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What is the root mean square velocity formula?
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square root of 3RT/M
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What are the units for root mean square velocity?
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m/s
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What is the value for R in the root mean square velocity formula?
answer
8.3145 J/molK
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What is the si unit for energy
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Joule
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What is the average distance a particle travels between collisions in a particular gas sample
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mean free path
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What is the ration of the number of moles of a given component in a mixture both total number of moles in the mixture?
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mole fraction
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mixing of gases
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diffusion
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passage of a gash through a tiny orifice into a vacuum
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effusion
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rate of the mixing of gases
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rate of diffusion
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measure the speed at which the gas is transferred into the chamber
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rate of effusion
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What is the formula for Graham's law of effusion?
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Rate of effusion for gas 1/rate of effusion for gas 2
square root of M2/ square root of M1
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Who developed an equation for real gases?
answer
Johannes van der Waals
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layer of atmosphere closest to earth with all clouds and weather
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troposphere
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What are the two main sources of pollution?
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transportation and production of electricity
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Would gases act more ideally with a few moles involved or a great number of moles involved?
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few, gases don't like to be close together
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One mole of gas contains how many molecules?
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6.02x10^23
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One mole of any gas occupies how many liters at STP?
answer
22.4
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Diatomic molecules exhibit what kind of bonding? (share electrons equally)
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non polar covalent
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Which of the following gases diffuse faster? Oxygen gas or Butane gas? Why?
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Oxygen, mass of oxygen is less than mass of butane
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average kinetic energy
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temperature
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If all the gases have the same temperature, what happens?
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they all have the same kinetic energy
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If volume increases on a gas, what happens to pressure?
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decreases (Boyle's Law)
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Gases act most ideally under what conditions?
answer
high temperature and low pressure
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What factor is used to determine if gases have the same partial pressures?
answer
moles
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Would a gas exert greater pressure as an ideal gas or as a real gas?
answer
ideal gas (postulates)
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