Question 1

The value of the gas constant R is equal to ________ L∙atm/ K∙mole.

Accepted Answer

The gas constant R has a value of 0.0821 L∙atm/K∙mol, as commonly used in chemistry calculations.

Question 2

Pressure is defined as ________.

Accepted Answer

Pressure is the amount of force per unit area, meaning it is the measure of how much force is applied to a certain area. Option B and D are incorrect as they refer to unit volume instead of unit area. Option C is incorrect as it refers to work done instead of force applied.

Question 3

For an ideal gas, which pairs of the variables below are directly proportional to each assuming all other variables are kept constant?

Accepted Answer

According to the ideal gas law (PV = nRT), pressure (P) and the amount of gas (n) are directly proportional when temperature (T) and volume (V) are kept constant.

Question 4

A gas under an initial pressure of 0.60 atm is compressed at constant temperature from 27 L to 3.0 L. The final pressure becomes ________.

Accepted Answer

According to Boyle's Law, at constant temperature, the pressure of a gas is inversely proportional to its volume. Therefore, if the volume decreases from 27 L to 3.0 L, a factor of 9, the pressure increases by the same factor. Thus, the final pressure is 0.60 atm * 9 = 5.4 atm.

Question 5

855 torr is equal to ________ cm Hg.

Accepted Answer

1 torr is equal to 1 mmHg and 1 cm = 10 mm. Therefore, to convert torr to cmHg, we need to divide by 10. 
855 torr ÷ 10 = 85.5 cmHg

Question 6

A gas occupies a volume of 480 mL at 127 °C and 140 mm Hg. What mathematical expression will yield the correct volume at 177 °C and 400 mm Hg?

Accepted Answer

The answer of A gas occupies a volume of 480...

Question 7

STP conditions stand for ________.

Accepted Answer

STP conditions refer to 0 °C and 760 mm Hg or 1 atm. The correct choice is C, which matches these conditions. Choices A and D are incorrect because they refer to 0 K, which is impossible to achieve, and 760 cm Hg, which is a measurement unit that is not commonly used. Choice B is incorrect because it refers to 0 °C and 760 cm Hg instead of 760 mm Hg.

Question 8

A gas sample occupies a volume of 8 L at 20 °C. The temperature at which the gas would double its volume is ________.

Accepted Answer

We can use the Gay-Lussac's Law, which states that the pressure of a gas is directly proportional to its temperature at constant volume. Therefore, we can write:
P1/T1 = P2/T2
where P1 and T1 are the initial pressure and temperature, and P2 and T2 are the final pressure and temperature. We can assume that the pressure is constant, so we can simplify the equation to:
T2 = T1(V2/V1)
where V1 and V2 are the initial and final volumes of the gas, respectively. If we want the gas to double its volume, we need V2 = 2V1. Substituting this into the equation, we get:
T2 = T1(2/1) = 2T1
Converting the initial temperature to Kelvin, we get:
T1 = 20 + 273 = 293 K
Therefore, the temperature at which the gas would double its volume is:
T2 = 2T1 = 2(293) = 586 K. 
Hence, the answer is D.

Question 9

If the pressure of a given gas sample doubles, what happens to the volume of gas? (Assuming that the amount of gas and the temperature of the gas stay the same).

Accepted Answer

According to Boyle's Law, if the pressure of a fixed amount of gas at a constant temperature is increased, the volume of the gas will decrease in proportion. Mathematically, P1V1 = P2V2, where P1 and V1 are the initial pressure and volume, and P2 and V2 are the final pressure and volume. If the pressure is doubled (P2 = 2P1), then the volume must be halved (V2 = V1/2) to maintain the same amount of gas at the same temperature. Thus, the volume will decrease by a factor of 2.

Question 10

1 atm is equal to ________.

Accepted Answer

The definition of 1 atm is the pressure exerted by a column of mercury 760 mm (or 76 cm) in height, hence 1 atm is equal to 760 mm Hg. Torr is an alternative unit for mm Hg, hence option C is also correct. However, option A is incorrect as 1 atm is not equal to 760 cm Hg and option D is incorrect as it is the same as option B.

Question 11

0.15 atm is equal to ________.

Accepted Answer

1 atm = 760 torr
Therefore, 0.15 atm = 0.15 x 760 torr = 114 torr.

Question 12

If the pressure of a gas sample is quadrupled and the absolute temperature is doubled, by what factor does the volume of the sample change?

Accepted Answer

According to the combined gas law, PV/T = constant. When pressure is quadrupled (i.e. multiplied by 4) and absolute temperature is doubled (i.e. multiplied by 2), the constant remains unchanged. Therefore, we can set up the following equation: 
P1V1/T1 = P2V2/T2 
(4P1)(V1)/(2T1) = P2V2/T2 
2V1 = V2 
This means that the volume of the gas sample is halved (i.e. divided by 2). Therefore, the factor by which the volume changes is 1/2.

Question 13

The number of moles of hydrogen gas present in a 1,500 mL container at 298 K and 2.0 atm pressure is ________.

Accepted Answer

The answer of The number of moles of hydrogen gas...

Question 14

How many moles of gas are found in a container that occupies a volume of 5.50 L with a pressure of 0.335 atm at 25 °C?

Accepted Answer

Using the ideal gas law, PV = nRT, where P = 0.335 atm, V = 5.50 L, R = 0.0821 L·atm/mol·K, and T = 298 K (25 °C + 273), we solve for n (moles): n = PV/RT = (0.335 * 5.50) / (0.0821 * 298) ≈ 0.0753 moles.

Question 15

A gas occupies 2.00 L at 298 K and 2.10 atm. The volume of this quantity of gas at STP conditions is ________.

Accepted Answer

We can use the combined gas law to solve for the volume at STP conditions:

(P1V1/T1) = (P2V2/T2)

We know: 
P1 = 2.10 atm 
V1 = 2.00 L 
T1 = 298 K

At STP, 
P2 = 1 atm 
T2 = 273 K

Plugging in these values:

(2.10 atm * 2.00 L) / 298 K = (1 atm * V2) / 273 K

Solving for V2:

V2 = (1 atm * 2.00 L * 273 K) / (2.10 atm * 298 K)

V2 = 3.84 L

Therefore, the answer is C.

Question 16

Which of the following gases will have the same density at STP?

Accepted Answer

At standard temperature and pressure (STP), gases have the same density if they have the same molar mass. Carbon monoxide (CO) and nitrogen (N2) both have a molar mass of approximately 28 grams per mole, making their densities equal at STP.

Question 17

For an ideal gas, which pairs of the variables below are inversely proportional to each assuming all other variables are kept constant?

Accepted Answer

According to Boyle's Law, at constant temperature, the volume of a gas is inversely proportional to its pressure. Therefore, if pressure (P) and volume (V) are both kept constant and one is increased, the other must be decreased.

Question 18

A gas occupies a volume of 0.500 L at 125 °C and 0.443 atm. What mathematical expression will yield the correct temperature at 0.750 L and 0.689 atm?

Accepted Answer

We can use the combined gas law to solve for the unknown temperature. The combined gas law states that:
(P1V1)/T1 = (P2V2)/T2
We can rearrange this equation to solve for T2:
T2 = (P2V2*T1)/(P1V1)
Plugging in the given values:
T2 = (0.689 atm * 0.750 L * 125°C) / (0.443 atm * 0.500 L)
Simplifying:
T2 = 398 K
Therefore, the correct choice is D.

Question 19

380 mm Hg is equal to ________ atm.

Accepted Answer

1 atm is equal to 760 mm Hg, so 380 mm Hg is equal to 380/760 = 0.500 atm.

Question 20

The volume of 2.3 g nitrogen gas at STP is ________.

Accepted Answer

At STP (Standard Temperature and Pressure), 1 mole of any gas occupies 22.4 liters. The molar mass of nitrogen gas (N2) is approximately 28 g/mol. Therefore, 2.3 g of nitrogen gas is 2.3/28 = 0.08214 moles. The volume occupied by this amount of gas at STP is 0.08214 moles * 22.4 L/mol = 1.84 L, which rounds to 1.8 L.

Quiz 11: What If There Were No Intermolecular Forces the Ideal Gas