CHEM Chapter 10&11 Test

The gas laws are

simple mathematical relationships between the volume, temperature, pressure, and amount of a gas.

Graham's law of effusion

states that the rates of effusion of gases at the same temperature and pressure are inversely proportional to the square roots of their molar masses.

Dalton's law of partial pressures

states that the total pressure of a mixture of gases is equal to the sum of the partial pressures of the component gases.

Charles's law

states that the volume of a fixed mass of gas at constant pressure varies directly with the Kelvin temperature.

Boyle's law

states that the volume of a fixed mass of gas varies inversely with the pressure at constant temperature.

Match the process on the right with the change of state on the left: solid to gas

sublimation

The average speed of a gas molecule is most directly related to the

temperature of the gas

The ideal gas law is

the mathematical relationship among pressure, volume, temperature, and the number of moles of a gas.

When a substance in a closed system undergoes a phase change and the system reaches equilibrium,

the two opposing changes occur at equal rates.

hydrogen bonding in liquid water

intermolecular

the bonds that cause gaseous Cl2 to become a liquid when cooled

intermolecular

the O—H covalent bond in methanol, CH3OH

intramolecular

Pressure

is defined as the force per unit area on a surface

ionic crystal

is hard, brittle, and non conducting

Explain your reasoning for the order of gases you chose in item 1 above. Refer to the kinetic molecular theory to support your explanation and cite Graham's law of effusion.

All gases at the same temperature have the same average kinetic energy. Therefore, heavier molecules have slower average speeds. Graham's law states that molecular speeds vary inversely with the square roots of their molar masses. Thus, the gases are ranked from heaviest to lightest in molar mass.

Explain why you put the gases in the order above. Refer to the kinetic-molecular theory to support your explanation.

All gases at the same temperature have the same average kinetic energy. Therefore, heavier molecules have slower average speeds. Thus, the gases are ranked from heaviest to lightest in molar mass.

List the following gases in order of rate of effusion, from lowest to highest. (Assume all gases are at the same temperature and pressure.) (a) He (b) Xe (c) HCl (d) Cl2

b, d, c, a

The kinetic-molecular theory is

based on the idea that particles of matter are always in motion.

A water molecule contains one atom of oxygen and two atoms of hydrogen.

chemical

There are strong hydrogen bonds between water molecules.

chemical

As a gas is heated, its rate of effusion through a small hole increases if all other factors remain constant.

As a gas is heated, each molecule's speed increases; therefore, the molecules pass through the small hole more frequently.

What is the relationship between vaporization and evaporation?

Evaporation is a form of vaporization. It occurs only in non boiling liquids when some liquid particles enter the gas state. Vaporization is a more general term that refers to either a liquid or a solid changing to a gas.

fluids

Because liquids and gases flow, they are both referred to as

The two samples must have equal masses. True or False?

False

A strong-smelling gas released from a container in the middle of a room is soon detected in all areas of that room

Gas molecules are in constant, rapid, random motion.

Explain the following properties of liquids by describing what is occurring at the molecular level: Polar liquids are slower to evaporate than nonpolar liquids.

Polar molecules are attracted to adjacent molecules and are therefore less able to escape from the liquid's surface than are nonpolar molecules.

Explain why polar gas molecules experience larger deviations from ideal behav

Polar molecules attract neighboring polar molecules and often move out of their straight-line paths because of these attractions.

Chemists distinguish between intermolecular and intramolecular forces. Explain the difference between these two types of forces.

Intermolecular forces are between separate molecules; intramolecular forces are within individual molecules.

The volume of a solid changes only slightly with a change in temperature or pressure.

Solids have definite volume because their particles are packed very close together. There is very little empty space into which the particles can be compressed. Even at high temperatures their particles are held in relatively fixed positions.

Explain the following properties of liquids by describing what is occurring at the molecular level: A liquid takes the shape of its container but does not expand to fill its volume.

Liquid molecules are very mobile. This mobility allows a liquid to take the shape of its container. In liquids, molecules are in contact with adjacent molecules, allowing intermolecular forces to have a greater effect than they do in gases. The molecules in a liquid will therefore not necessarily spread out to fill a container's entire volume.

When 1 mol of a real gas is condensed to a liquid, the volume shrinks by a factor of about 1000.

Molecules in a gas are far apart. They are much closer together in a liquid. Molecules in a gas are easily squeezed closer together as the gas is compressed.

Which of the following statements about liquids and gases is not true?

Molecules in a liquid can vibrate and rotate, but they are bound in fixed positions.

Explain how the ideal gas law can be simplified to give Avogadro's law, expressed as V/n=k, when the pressure and temperature of a gas are held constant.

Rearrange PV nRT to obtain V/n=RT/P Because every value for RT/P is the same, its overall value is constant; therefore, V/n=k

diffusion

Such spontaneous mixing of the particles of two substances caused by their random motion

As long as temperature is constant, what happens to the kinetic energy of the colliding particles during an elastic collision?

The energy is transferred between them

Gay-Lussac's law of combining volumes of gases.

The law states that at constant temperature and pressure, the volumes of gaseous reactants and products can be expressed as ratios of small whole numbers

Gay-Lussac's law

The pressure of a fixed mass of gas at constant volume varies directly with the Kelvin temperature.

partial pressure

The pressure of each gas in a mixture is called_____ of that gas

absolute zero

The temperature −273.15°C is referred to as ______ and is given a value of zero in the Kelvin scale

If two gases have the same temperature and share the same energy but have different molecular masses, which molecules will have the greater speed?

Those with the lower molecule mass.

The two flasks must contain an equal number of molecules. True or False?

True

deposition

a change directly from a gas to a solid

real gas

a gas that does not behave completely according to the assumptions of the kinetic-molecular theory.

effusion

a process by which gas particles pass through a tiny opening.

Answer amorphous solid or crystalline solid to the following questions: . Which is sometimes described as a supercooled liquid?

amorphous solid

Answer amorphous solid or crystalline solid to the following questions: Which has a less clearly defined melting point?

amorphous solid

An ideal gas is

an imaginary gas that perfectly fits all the assumptions of the kinetic molecular theory

Match the process on the right with the change of state on the left: gas to liquid

condensation

Answer amorphous solid or crystalline solid to the following questions: Which has a more clearly defined shape?

crystalline solid

Answer amorphous solid or crystalline solid to the following questions: Which is less compressible?

crystalline solid

Avogadro's law

equal volumes of gases at the same temperature and pressure contain equal numbers of molecules

Compare a polar water molecule with a less-polar molecule, such as formaldehyde, CH2O. Both are liquids at room temperature and 1 atm pressure.:

formaldehyde

metallic crystal

has mobile electrons in the crystal

covalent network crystal

has strong covalent bonds between neighboring atoms

Collisions between molecules are perfectly elastic.

ideal gas

The gas will not condense because the molecules do not attract each other.

ideal gas

For the expression V=nRT/P which of the following will cause the volume to increase?

increasing T

Match the process on the right with the change of state on the left: solid to liquid

melting

fusion

melting

The molar mass of a gas at STP is the density of that gas

multiplied by 22.4 L.

An elastic collision is

one in which there is no net loss of kinetic energy.

equilibrium

opposing changes occurring at equal rates in a closed system

Ice consists of water molecules in a hexagonal arrangement.

physical

The density of ice is less than the density of liquid water.

physical

volatile

readily evaporated

Gas particles passing close to one another exert an attraction on each other.

real gas

Liquids possess all the following properties except

relatively low density.

covalent molecular crystal

typically has the lowest melting point of the four crystal types

Match the process on the right with the change of state on the left: liquid to gas

vaporization

Compare a polar water molecule with a less-polar molecule, such as formaldehyde, CH2O. Both are liquids at room temperature and 1 atm pressure.:

water

Compare a polar water molecule with a less-polar molecule, such as formaldehyde, CH2O. Both are liquids at room temperature and 1 atm pressure.: Which liquid should have the higher boiling point?

water