Chemistry Chapter 11

Front 1

Kinetic molecular Theory

Back 1

The kinetic molecular theory is a model for gases. In this model, gases are composed of widely spaced, noninteracting particles whose average kinetic energy depends on temperature.

Front 2

Kinetic molecular theory relevance

Back 2

The kinetic molecular theory predicts many of the properties of gases, including their low density in comparison to solids, their compressibility, and their tendency to assume the shape and volume of their container. The kinetic molecular theory also predicts the ideal gas law.

Front 3

Pressure

Back 3

Pressure is the force per unit area that results from the collision of gas particles with surfaces. The SI unit of pressure is the pascal, but pressure is often expressed in other units such as atmospheres, millimeteres of mercury, torr, pounds per square inch, and inches of mercury.

Front 4

Pressure releveance

Back 4

ressure is a fundamental property of a gas. It allows tires to be inflated and makes it possible to drink from straws.

Front 5

What is pressure?

Back 5

Pressure is the push (or force) exerted per unit area by gaseous molecules as they collide with the surfaces around them.

Front 6

Explain how drinking from a straw works. What causes the drink to go up the straw?

Back 6

Straws work because sucking creates a pressure difference between the inside of the straw and the outside. When you suck on a straw you remove some of the air molecules lowering the number of collisions that occur inside teh straw and therefore lowering the pressure. The pressure outside the straw remains the same resulting in a pressure differential. The pressure ourside the straw becomes greater than the pressure inside the straw. The greater external pressure pushes the liquid up the straw and into your mouth.

Front 7

Is there an upper limit to how long a straw can be and still work as a drinking straw?

Back 7

The longest straw that could work would be 10.3 m.

Front 8

What are the main assumptions in kinetic molecular theory?

Back 8

1. Collection of particles are in constant motion.
2. No attractions or repulsions exist between particles, collisions are like billiard balls.
3. There is alot of space between the particles compared to the size of the particles themselves.
4. The speed of the particles increases with increasing temp.

Front 9

Describe the main properties of a gas. how are these predicted by kinetic molecular theory?

Back 9

Gases are compressible due to the large amount of empty space between their molecules. Gases assume the shape and volume of their container because the atoms or molecules are in constant motion. Gases have low densities because they are mostly empty space.

Front 10

Why do we experience pain in our ears during changes in altitude?

Back 10

The pain you feel in your ears upon climbing a mountain or flying in an airplane is caused by an imbalance of pressure between the cavities inside your ear and the outside air.The greater internal pressure causes your eardrum to bulge outward, causing pain. With time and a yawn the excess air within your ears cavitites escapes, equalizing the pressure and relieving the pain.

Front 11

What are the main units used to measure pressure?

Back 11

The main units used to measure pressure are Pa, atm, mm Hg, and Torr.

Front 12

What is Boyle's law?

Back 12

The volume of a gas and its pressure are inversely related.

Front 13

Explain Boyle's law from the perspective of kinetic molecular theory.

Back 13

boyle's law from the perspective of kinetic molecular theory states that if the volume of a gas container is decreased, the same number of gas particles is crowded into a smaller volume causing more collisions with the walls of the container and therefore increasing the pressure.

Front 14

Explain why scuba divers should not hold their breath as they ascend to the surface.

Back 14

Since the pressure decreases the volume of air in his lungs would be so great that the diver would bot be able to hold his breath all the way to te surface. the air would force itself out of the diver's mouth.

Front 15

Why would it be impossible to breathe air through an extra long snorkel while swimming under water?

Back 15

When an individual is more than a couple meters under water, the air pressure in the lungs is greater thna the air pressure at the water's surface. If a snorkel were used, it would move the air from the lungs to the surface, making it difficult to breathe.

Front 16

What is Charle's law?

Back 16

The volume of a gas and its Kelvin temperature are directly proportional.

Front 17

Explain Charles's law from the perspective of kinetic molecular theory.

Back 17

Charles's law from the perspective of kinetic molecular theory states that if the temperature of a gas in increased, the particles move faster and will collectively occupy more space.

Front 18

Explain why hot air balloons float above the ground.

Back 18

Heating the balloon makes it expand (Charles's law). As the volume occupied by the hot air increases, its density decreases, allowing the balloon to floar in the cooler air that surrounds it.

Front 19

What is the combined gas law? When is it useful?

Back 19

The combined gas law is P1V1/T1=P2V2/T2. It is useful when more than one variable of a gas changes at the same time.

Front 20

What is Avogadro's law?

Back 20

The volume of a gas and the amound of the gas in moles are directly proportional.

Front 21

Explain Avogadro's law from the perspective of kintic molecular theory.

Back 21

Avogadro's law, from the perspective of kinetic molecular theory, states that if the number of particles increases, they occupy more volume.

Front 22

What is the ideal gas law? When is it useful?

Back 22

The ideal gas law is PV=nRT. It is useful when we want to know how other pairs of variables are related.

Front 23

Under what conditions is the ideal gas law most accurate? Under what conditions does the id3eal gas law break down? Why?

Back 23

The ideal gas law is most accurate when the volume of gas particles is small compared to the space between them. It is also accurate when the forces between particles are not important. The ideal gas law breaks down at high pressures and low temperatures. This breakdown occurs because the gases are no longer acting according to the kinetic molecular theory.

Front 24

What is partial pressure?

Back 24

The partial pressure of any compound is the component's fractional composition times the total pressure of the mixture.

Front 25

What is Dalton's law?

Back 25

Ptot is the total pressure of Pa, Pb, Pc.....are the partial pressures of the components.

Front 26

Describe hypoxia and oxygen toxicity.

Back 26

Low oxygen levels have physiological effects and can result in a condition called hypoxia, or oxygen starvation. Mild hypoxia causes dizziness, headache, and shortness of breathe. Severe hypoxia occurs when PO2 drops below .1atm can result in unconsciousness or death. Oxygen toxisity occurs when the increased pressure of oxygen results in a higher density of oxygem molecules in body tissues. When PO2 ncreases beyond 1.4atm oxyten toxisity occurs and muscles twitch tunnel vision and convulsions also occur.

Front 27

Why do deep sea divers breathe a mix of helium and oxygen?

Back 27

Deep sea divers breathe helium with oxygen because helium, unlike nitrogen, does not have physiological effects under high pressure conditions. The oxygen concentration in the mixture is low to avoid oxygen toxicity.

Front 28

when a gas is collected over water, is the gas pure? Why or why not?

Back 28

It is not pure byt is mixed with water vapor because some of the water molecules evaporate and become mixed with the hydrogen molecules.

Front 29

What is vapor pressure?

Back 29

Vapor pressure is the partial pressure of a gas above its liquid. Partial pressure increases with increasing temperature.

Front 30

What is standard temperature and pressure (STP)? What is the molar volume of a gas at STP?

Back 30

STP is the volume occupied by 1 mol of gas at 0 degrees celcius and 1 atm. 1 mol=22.4L

Front 31

If you increase pressure what happens to volume?

Back 31

If you increase pressure volume decreases according to Boyle's law which states they have an inverse relatonship.

Front 32

If you decrease pressure what happens to volume?

Back 32

If you decrease pressure volume increases according to Boyle's law which states they have an inverse relationship.

Front 33

If you increase temperature what happens to volume?

Back 33

If you increase temperature, volume will increase according to Charles's law which states that the variables are directly proportional.

Front 34

If you decrease temperature what happens to volume?

Back 34

If you decrease temperature, volume will decrease according to charles's law which states that the variables are directly proprotional.

Front 35

When you increase the amount of gas what happens to the volume?

Back 35

The volume increases.

Front 36

According to kinetic molecular theory in Dalton's law of partial pressure what is true of the partial pressures?

Back 36

The partial pressures of each of the componenets in a gas mixture acts independently of the others.