Chem chapter 8

The barometric pressure given in the local weather report is reported as inHg. What is the pressure in mmHg if the weatherman says the current pressure today is 29.75 in Hg?

755.7 mmHg

The number of mm Hg in one atmosphere is

760

When a liquid sample is taken from sea level to a higher elevation, what happens to the external (atmospheric) pressure on the liquid and the boiling point of the liquid?

Both decrease

Which of the following cannot have hydrogen bonds? A) CH3NH2 B) NH3 C) HCl D) HF E) H2O

HCl

As the temperature of a liquid is lowered, what happens to its vapor pressure?

Its vapor pressure drops.

Using the kinetic molecular theory, as the temperature of a gas rises the pressure will also increase because

both the gas molecules collide more frequently and more energetically with the wall of the container.

In comparing gases with liquids, gases have ________ compressibility and ________ density.

greater; smaller

Which is not a correct statement of Boyle's Law?

none of the above

Which represents the largest pressure? A) five pounds per square inch B) one atmosphere C) five mm Hg D) one hundred pascals E) one millimeter of mercury

one atmosphere

The total pressure of a mixture of gases is

sum of partial pressures

Which is the best description of hydrogen bonding?

the association between a hydrogen atom which is somewhat positive because it is bonded to a small electronegative atom and an atom of O, N or F on another molecule

When the volume of a gas is plotted against the Celsius temperature while holding pressure and the number of moles constant, the x-intercept will occur at what temperature?

-273°C

A 65 mL sample of argon gas has a temperature of 325°C. What will the temperature be in °C when the volume of the gas is decreased to 25 mL at constant pressure?

-43°C

A sample of CO2 gas at 100.°C has a volume of 250. mL at 760. mm Hg. How many moles of CO2 are present?

0.00816 mol

A balloon originally had a volume of 4.39 L at 44°C and a pressure of 729 torr. To what temperature must the balloon be cooled to reduce its volume to 3.78 L if the pressure is constant?

0.0°C

How many moles of gas are present in a 10.0 liter sample at STP?

0.446 moles

A 250. mL sample of gas at 1.00 atm and 20.0°C has the temperature increased to 40.0°C and the volume increased to 500. mL. What is the new pressure?

0.534 atm

Which measurement represents the smallest value of pressure? A) 755 torr B) 22.0 psi C) 100 kPa D) 0.750 atm E) 785 mm Hg

0.750 atm

If the temperature of a 1.75 liter sample of gas is changed from 30.0°C to 20.0°C at constant pressure, what will be the new volume?

1.69 L

What is the total pressure of a mixture of He and H2 if the partial pressures are 320 mm Hg and 800 mm Hg respectively?

1120 mm Hg

Chlorine gas is widely used to purify municipal water supplies and to treat swimming pool waters. Suppose that the volume of a particular sample of Cl2 is 718 mL at 675 mmHg and 48°C, at what temperature (in °C) will the volume be 2.00 L if the pressure is 159 kPa?

1308°C

What will be the new volume when 128 mL of gas at 20.0°C is heated to 40.0°C while pressure remains unchanged?

137 mL

How many grams of N2 are contained in an 11.2 liter sample at STP?

14.0

How many grams of O2 are contained in a 25.0 L sample at 5.20 atm and 28.0°C?

168 g

What would be the new pressure if a 400 mL gas sample at 380 mm Hg is expanded to 800 mL with no change in temperature?

190 mm Hg

A sealed container with gas at 2.00 atm is heated from 20.0 K to 40.0 K. The new pressure is

2.14 atm.

Which measurement represents the largest value of pressure? A) 785 mm Hg B) 22.0 psi C) 100 kPa D) 0.750 atm E) 755 torr

22.0 psi

Which of the following is the definition of standard temperature and pressure?

273 K and 760 mm Hg

What is the new volume of a balloon originally at 755 torr and 5.00 L is placed in a container in which the pressure is increased to 1.25 atm?

3.97 L

For the following reaction, if 11.2 L of nitrogen are reacted to form NH3 at STP, how many liters of hydrogen will be required to completely consume all of the nitrogen?

33.6 L

A mixture of the gases N2, O2, and He has a total pressure of 760 mm Hg. If the partial pressure of N2 is 90 mm Hg and of O2 is 270 mm Hg, what is the partial pressure of He?

400 mm Hg

A sample of gas has a volume of 135 mL at 0.600 atm. What would be the volume if the pressure is decreased to 0.200 atm while temperature is held constant?

405 mL

If a 0.614 g sample of a gas maintains a pressure of 238 mm Hg when contained in a 1.0 L flask at 0.0°C, what is molar mass of the gas?

44 g/mol

What volume will be occupied by 8.00 g of oxygen, O2, at STP?

5.60 L

In a gas mixture of 35% He and 65% O2 the total pressure is 800 mm Hg. What is the partial pressure of O2?

520 mm Hg

A sample of helium has a volume of 480 mL at 47.0°C and 740 mm Hg. The temperature is lowered to 22.0°C and the pressure to 625 mm Hg. What is the new volume?

524 mL

What is the pressure in a 1.00 liter container of methane, CH4, that contains 40.0 g of the gas at 25.0°C?

61.0 atm

Calculate the volume of 5.00 mol of helium at 120.°C and 1520 mm Hg.

80.6 liters

Calculate the volume of a 3.50 mol sample of carbon dioxide at 30.0°C and 0.900 atm.

96.7 L

What is the total pressure of a gaseous mixture that contains three gases with partial pressures of 0.845 atm, 120 torr, and 210 mm Hg?

972 torr

A solid compound which has no definite crystalline structure and a poorly defined melting point is referred to as a(an) ________ solid.

Amorphous

Which is a correct statement of Gay-Lussac's Law describing the behavior of a fixed amount of gas?

As temperature increases, pressure increases at constant volume

Which molecule will undergo only London dispersion forces when interacting with other molecules of the same kind?

C4H10

Which description best fits a liquid?

Definite volume, shape of container, moderate intermolecular attractions

Consider a sample of helium and a sample of neon, both at 30.0°C and 1.5 atm. Both samples have a volume of 5.0 liters. Which statement concerning these samples is not true?

Each sample weighs the same amount

Which is not a correct statement of Charles's Law?

For a gas sample at constant pressure, temperature and volume are inversely proportional

Which of the assumptions of the kinetic-molecular theory best explains Dalton's law of partial pressures?

Gas molecules move at random with no attractive forces between them

Which assumption of Kinetic Molecular Theory is not followed when a real gas shows non-ideal behavior?

Gas molecules move at random with no attractive forces between them.

Which process is exothermic?

Gas to liquid

Which process is endothermic?

Gasoline spilled on the ground evaporates very quickly.

The amount of energy involved in melting a substance without changing its temperature is called the

Heat of fusion

Which combination of characteristics is most likely to be associated with molecules having strong dipole-dipole interactions? I . polar bond II. asymmetric shape III. relatively low boiling point IV. large surface area

I and II

How will the volume of a fixed sample of gas change if the pressure is doubled and its Celsius temperature is halved?

It will double

How will the volume of a fixed sample of gas change if its pressure is doubled and the Kelvin temperature is doubled?

It will not change

What are the strongest intermolecular forces between pentane (C5H12) molecules?

London dispersion forces

Arrange the following in order of increasing intermolecular forces: N2 CH3CH2OH CO2 HCl

N2 < CO2 < HCl < CH3CH2OH

Rank the following in increasing order of increasing boiling point: N2 CH3CH2OH CO2 HCl

N2 < CO2 < HCl < CH3CH2OH

Which pair of molecules has the strongest dipole-dipole interactions?

NH3 and NH3

Which of the assumptions of the kinetic-molecular theory best explains the observation that a balloon collapses when exposed to liquid nitrogen (which is much colder than a cold winter day!!)?

The velocity of gas molecules is proportional to their Kelvin temperature.

Which description best fits a solid?

definite shape and volume; strong intermolecular attractions

The process of sublimation is ________ and involves a(an) ________ in entropy.

endothermic; increase

Which transformation is condensation?

gas → liquid

The amount of energy associated with changing a liquid into a gas is called the

heat of vaporization.

Most gases show variations from ideality at ________ pressure and ________ temperature.

high; low

Which intermolecular force is characteristic of compounds with low molar mass, which are liquids at room temperature and have relatively high boiling points?

hydrogen bonds

According to Avogadro's Law, the volume of a gas will ________ as the ________ is increased while the ________ are held constant.

increase; number of moles; pressure and temperature

Volume and pressure are ________ proportional.

inversely

The vapor pressure of a liquid

is equal to one atmosphere at the normal boiling point

Which transformation is evaporation?

liquid to gas

Which transformation is freezing?

liquid to solid

In comparing liquids and gases, liquids have ________ compressibility and ________ density.

smaller; greater

Which transformation is melting?

solid to liquid

Which transformation is sublimation?

solid → gas

Which of the assumptions of the kinetic-molecular theory best explains the observation that a gas can be compressed?

the amount of space occupied by a gas is much greature than the space occupied by the actual gas moleculs

At a high altitude water boils at 95°C instead of 100°C as at sea level because the

the atmospheric pressure is less

Which description best fits a gas?

volume and shape of container; no intermolecular attractions