Test 4 – Chemistry Test Answers – Flashcards
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| What uniformly fill any container, are easily compressed, and mix completely with like substances? |
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| gases |
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| Earth's atmosphere is about what percent of nitrogen? |
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| 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? |
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| 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= |
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| 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? |
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| 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? |
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| 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? |
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| 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 |
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| Dalton's Law of Partial Pressure |
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| What is made from sodium azide? |
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| 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? |
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| 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? |
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| 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? |
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| 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? |
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| high temperature and low pressure |
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| What factor is used to determine if gases have the same partial pressures? |
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| moles |
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| Would a gas exert greater pressure as an ideal gas or as a real gas? |
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| ideal gas (postulates) |
