Question 1

A 1.00 L flask contains nitrogen gas at 25°C and 1.00 atm pressure.What is the final pressure in the flask if an additional 0.50 g of N₂ gas is added to the flask and the flask cooled to -55°C? A)1.01 atm B)1.05 atm C)0.319 atm D)3.13 atm

Accepted Answer

Using the ideal gas law, calculate the initial moles of N2, add the moles from 0.50 g of N2, and then use the new temperature to find the final pressure.

Question 2

For an ideal gas,which pairs of variables are inversely proportional to each other (if all other factors remain constant)? I.P,T II.P,V III.V,T IV.n,T
A)I and II only
B)III and IV only
C)II only
D)I and III only

Accepted Answer

II onlyAccording to Boyle's Law, for a given amount of gas at constant temperature (T), the pressure (P) of the gas is inversely proportional to its volume (V), which is represented as P ∝ 1/V or PV = constant. This is the only pair among the options given where the variables are inversely proportional to each other under the condition that all other factors remain constant.

Question 3

What is the density of carbon monoxide gas at STP?
A)0.510 g/L
B)0.800 g/L
C)1.96 g/L
D)1.25 g/L

Accepted Answer

At STP (Standard Temperature and Pressure), the molar volume of any ideal gas is 22.4 L/mol. The molar mass of carbon monoxide (CO) is approximately 28.01 g/mol. Therefore, the density is calculated as 28.01 g/mol divided by 22.4 L/mol, which is approximately 1.25 g/L.

Question 4

You have two samples of the same gas in the same size container,with the same pressure.The gas in the first container has a Kelvin temperature four times that of the gas in the other container.The ratio of the number of moles of gas in the first container compared to that in the second is
A)1:1.
B)1:2.
C)1:4.
D)4:1.

Accepted Answer

According to the Ideal Gas Law, PV=nRT. Since the pressure and volume are the same for both gases, we can simplify the equation to n/T = constant. Therefore, the number of moles is directly proportional to the temperature. The temperature of the first container is four times that of the second container, so the number of moles in the first container is four times the number of moles in the second container. Therefore, the ratio of the number of moles in the first container to that in the second container is 4:1, which is choice D.

Question 5

A 0.429-g sample of gas occupies 125 mL at 60.cm of Hg and 25°C.What is the molar mass of the gas?
A)8.9 g/mol
B)66 g/mol
C)88 g/mol
D)106 g/mol

Accepted Answer

We can use the ideal gas law to solve for the moles of the gas:

PV = nRT

where P = 60 cm Hg = 0.79 atm (using the conversion factor 1 atm = 760 mm Hg), V = 125 mL = 0.125 L, T = 25°C = 298 K, and R = 0.0821 L atm/mol K.

n = (PV)/(RT) = (0.79 atm x 0.125 L)/(0.0821 L atm/mol K x 298 K) = 0.00486 mol

Then, we can use the definition of molar mass (mass/moles) to solve for the molar mass:

molar mass = mass/moles = 0.429 g/0.00486 mol = 88 g/mol

Therefore, the correct answer is D.

Question 6

A 1.75 L container filled with CO₂ gas at 25°C and 225 kPa pressure springs a leak.When the container is re-sealed,the pressure is 200 kPA and the temperature is 10°C.How many moles of gas were lost? A)0.0101 mol B)0.149 mol C)6.71 mol D)99.0 mol

Accepted Answer

Using the ideal gas law, we can calculate the number of moles of gas lost:PV = nRTn = PV/RTn1 = (225 kPa * 1.75 L) / (0.0821 L*atm/(mol*K) * 298 K) = 1.49 moln2 = (200 kPa * 1.75 L) / (0.0821 L*atm/(mol*K) * 283 K) = 1.39 moln_lost = n1 - n2 = 1.49 mol - 1.39 mol = 0.1 molTherefore, the correct answer is A) 0.1 mol.

Question 7

A gas occupies 22.4 L at STP and 9.85 L at 100.°C and 2.00 atm pressure.How many moles of gas did the system gain or lose?
A)1.36 moles gained
B)1.64 moles gained
C)0.644 moles lost
D)0.356 moles lost

Accepted Answer

Using the ideal gas law, the initial moles at STP (22.4 L, 1 atm, 273 K) is 1 mole. At 100°C (373 K) and 2 atm, the moles are calculated using PV=nRT, resulting in approximately 0.644 moles. Therefore, the system lost 0.356 moles (1 - 0.644).

Question 8

A steel bottle contains argon gas at STP.What is the final pressure if the temperature is changed to 85°C?
A)0.666 atm
B)0.762 atm
C)0.850 atm
D)1.31 atm

Accepted Answer

At STP, the temperature is 0°C, which is 273 K. The pressure of the argon gas is 1 atm. If we increase the temperature to 85°C, which is 358 K, the pressure will increase. We can use the ideal gas law to calculate the new pressure:

PV = nRT

where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature in Kelvin.

At STP, we have one mole of argon gas and a volume of 22.4 L, so we can rearrange the equation to solve for the new pressure:

P2 = (nRT2) / V

P2 = (1 mol x 0.08206 L atm / (mol K) x 358 K) / 22.4 L

P2 = 1.31 atm

Therefore, the final pressure is 1.31 atm, which is closest to choice D: 1.31 atm.

Question 9

What is the value of the gas constant,R,in units of ? A)1.080 × 10^-4 B)0.1080 C)62.36 D)6.236 × 10⁴

Accepted Answer

The value of the gas constant R can be expressed in different units depending on the system of measurement used. The most common unit for R is J/(mol·K) which corresponds to the SI (International System of Units). In this case, the value of R is approximately 8.314. However, the question asks for the value of R in a specific unit which is given as 11ea7e2d_d129_b20f_a2f7_5d416dd864dd_TB4940_11. This unit is not recognized as a standard unit of measurement and there is no way to determine its value without additional information. Therefore, the best choice is to select the answer that gives the closest value to the standard value of R in the given unit, which is option D, 6.236 × 10⁴.

Question 10

Chloroform is a volatile liquid once commonly used in the laboratory but now being phased out due to its ozone depletion potential.If the pressure of gaseous chloroform in a flask is 195 mm Hg at 25°C and its density is 1.25 g/L,what is the molar mass of chloroform?
A)10.0 g/mol
B)76.3 g/mol
C)119 g/mol
D)None of these

Accepted Answer

Using the ideal gas law equation in the form of $PV = nRT$, where $n = \frac{m}{M}$ (m is mass, M is molar mass), and given density ($\rho = \frac{m}{V}$), we can rearrange to find $M = \frac{RT}{P} \times \rho$. Substituting $R = 0.0821 \, \text{L atm K}^{-1} \text{mol}^{-1}$, $T = 298 \, \text{K}$ (25°C + 273), $P = 195 \, \text{mm Hg} \times \frac{1 \, \text{atm}}{760 \, \text{mm Hg}}$, and $\rho = 1.25 \, \text{g/L}$, we calculate $M$ to be approximately $119 \, \text{g/mol}$.

Question 11

What is the Celsius temperature of 100.0 g of chlorine gas in a 4.00-L container at 800 mm Hg?
A)309°C
B)-236°C
C)236°C
D)-309°C

Accepted Answer

Using the ideal gas law and converting units appropriately, the temperature is calculated to be approximately -236°C.

Question 12

Three identical flasks contain three different gases at standard temperature and pressure.Flask A contains Ar,flask B contains Ne,flask C contains H₂.Which flask contains the largest number of molecules? A)flask A B)flask B C)flask C D)All flasks contain the same number of molecules.

Accepted Answer

The number of molecules in a gas is directly proportional to its number of moles, which is given by the ideal gas law: n = PV/RT, where P is the pressure, V is the volume, R is the gas constant, and T is the temperature. Since all three gases are at the same temperature and pressure, and the flasks are identical, they have the same volume (V) and the same gas constant (R). Therefore, the number of molecules in each flask only depends on the number of moles (n) in each flask. Flask A, containing Ar, has one mole of gas, flask B, containing Ne, has one mole of gas, and flask C, containing H₂ (unknown gas), also has one mole of gas. Therefore, all flasks contain the same number of molecules.

Question 13

How many grams of H₂ gas are there in a 5.00-L cylinder at 4.00 × 10³ mm Hg and 23°C? A)1.08 g B)2.16 g C)0.542 g D)823 g

Accepted Answer

The answer of How many grams of H₂ gas are...

Question 14

A balloon filled with helium gas at 20°C occupies 2.91 L at 1.00 atm.The balloon is immersed in liquid nitrogen at -180°C,raising the pressure to 5.20 atm.What is the volume of the balloon in the liquid nitrogen?
A)0.178 L
B)5.62 L
C)5.04 L
D)0.199 L

Accepted Answer

The volume of the balloon in liquid nitrogen can be calculated using the combined gas law, which is $P_1V_1/T_1 = P_2V_2/T_2$. Given $P_1 = 1.00$ atm, $V_1 = 2.91$ L, $T_1 = 20°C = 293K$, $P_2 = 5.20$ atm, and $T_2 = -180°C = 93K$, solving for $V_2$ gives approximately $0.178$ L.

Question 15

The action of some commercial drain cleaners is based on the following reaction: 2 NaOH(s)+ 2 Al(s)+ 6 H₂O(l)→ 2 NaAl(OH)₄(s)+ 3 H₂(g) What is the volume of H₂ gas formed at STP when 8.64 g of Al reacts with excess NaOH? A)4.78 L B)7.18 L C)10.8 L D)11.7 L

Accepted Answer

First, we need to balance the equation:
2 NaOH(s) + 2 Al(s) + 6 H2SO4(l) → 2 NaAl(OH)4(s) + 3 H2S(g)

Now we can use stoichiometry to find the moles of H2S produced:
8.64 g Al × (1 mol Al/ 26.98 g Al) × (3 mol H2S / 2 mol Al) = 1.01 mol H2S

At STP, 1 mole of gas occupies 22.4 L. Therefore, the volume of H2S at STP is:
1.01 mol H2S × 22.4 L/mol = 22.6 L

However, this is the volume at STP, not the actual conditions present in the drain. We don't know the temperature and pressure of the drain, so we assume STP for simplicity.

Therefore, the answer is:
C) 10.8 L

Question 16

How many molecules of N₂ are in a 250.0 mL container at 780 mm Hg and 135°C? A)4.38 × 10²¹molecules B)4.62 × 10²¹molecules C)1.32 × 10²²molecules D)1.39 × 10²²molecules

Accepted Answer

To find the number of molecules, we can use the ideal gas law equation in the form of PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is temperature in Kelvin. First, we need to convert the given values to the appropriate units: pressure from mm Hg to atm (780 mm Hg / 760 mm Hg per atm), volume from mL to L (250.0 mL / 1000 mL per L), and temperature from °C to K (135°C + 273.15). Then, solve for n (moles) and convert moles to molecules using Avogadro's number (6.022 × 10^23 molecules/mol). The calculation will show that option B gives the correct number of molecules, considering the ideal gas law and the conversion factors.

Question 17

Cyanogen is a gas which contains 46.2% C and 53.8% N by mass.At a temperature of 25°C and a pressure of 750 mm Hg,1.50 g of cyanogen occupies 0.714 L.What is the molecular formula of cyanogen? A)CN B)C₂N₂ C)C₃N₄ D)C₄N₅

Accepted Answer

The molecular weight of cyanogen can be calculated using the ideal gas law. Using the given conditions, the molar mass is found to be approximately 52 g/mol. The empirical formula mass of CN is 26 g/mol, so the molecular formula is C₂N₂.

Question 18

A 75.0 L steel tank at 20.0°C contains acetylene gas,C₂H₂,at a pressure of 1.20 atm.Assuming ideal behavior,how many grams of acetylene are in the tank? A)3.74 g B)54.8 g C)97.3 g D)1425 g

Accepted Answer

The answer of A 75.0 L steel tank at 20.0°C...

Question 19

What is the volume of 10.0 g of oxygen gas at 157°C and 2.50 kPa pressure?
A)51.5 L
B)163 L
C)1.61 L
D)447 L

Accepted Answer

The answer of What is the volume of 10.0 g...

Question 20

Which of the following would have a density of 1.89 g/L at 7.0°C and 0.987 atm? A)Ar B)CO₂ C)CO D)O₂

Accepted Answer

Using the ideal gas law, the molar mass of CO2 is approximately 44 g/mol, which matches the given density under the specified conditions.

Quiz 10: Gases: Their Properties and Behavior

A 1.00 L flask contains nitrogen gas at 25°C and 1.00 atm pressure.What is the final pressure in the flask if an additional 0.50 g of N₂ gas is added to the flask and the flask cooled to -55°C?

For an ideal gas,which pairs of variables are inversely proportional to each other (if all other factors remain constant) ? I.P,T II.P,V III.V,T IV.n,T

What is the density of carbon monoxide gas at STP?

You have two samples of the same gas in the same size container,with the same pressure.The gas in the first container has a Kelvin temperature four times that of the gas in the other container.The ratio of the number of moles of gas in the first container compared to that in the second is

A 0.429-g sample of gas occupies 125 mL at 60.cm of Hg and 25°C.What is the molar mass of the gas?

A 1.75 L container filled with CO₂ gas at 25°C and 225 kPa pressure springs a leak.When the container is re-sealed,the pressure is 200 kPA and the temperature is 10°C.How many moles of gas were lost?

A gas occupies 22.4 L at STP and 9.85 L at 100.°C and 2.00 atm pressure.How many moles of gas did the system gain or lose?

A steel bottle contains argon gas at STP.What is the final pressure if the temperature is changed to 85°C?

What is the value of the gas constant,R,in units of ?

Chloroform is a volatile liquid once commonly used in the laboratory but now being phased out due to its ozone depletion potential.If the pressure of gaseous chloroform in a flask is 195 mm Hg at 25°C and its density is 1.25 g/L,what is the molar mass of chloroform?

What is the Celsius temperature of 100.0 g of chlorine gas in a 4.00-L container at 800 mm Hg?

Three identical flasks contain three different gases at standard temperature and pressure.Flask A contains Ar,flask B contains Ne,flask C contains H₂.Which flask contains the largest number of molecules?

How many grams of H₂ gas are there in a 5.00-L cylinder at 4.00 × 10³ mm Hg and 23°C?

A balloon filled with helium gas at 20°C occupies 2.91 L at 1.00 atm.The balloon is immersed in liquid nitrogen at -180°C,raising the pressure to 5.20 atm.What is the volume of the balloon in the liquid nitrogen?

The action of some commercial drain cleaners is based on the following reaction: 2 NaOH(s) + 2 Al(s) + 6 H₂O(l) → 2 NaAl(OH) ₄(s) + 3 H₂(g) What is the volume of H₂ gas formed at STP when 8.64 g of Al reacts with excess NaOH?

How many molecules of N₂ are in a 250.0 mL container at 780 mm Hg and 135°C?

Cyanogen is a gas which contains 46.2% C and 53.8% N by mass.At a temperature of 25°C and a pressure of 750 mm Hg,1.50 g of cyanogen occupies 0.714 L.What is the molecular formula of cyanogen?

A 75.0 L steel tank at 20.0°C contains acetylene gas,C₂H₂,at a pressure of 1.20 atm.Assuming ideal behavior,how many grams of acetylene are in the tank?

What is the volume of 10.0 g of oxygen gas at 157°C and 2.50 kPa pressure?

Which of the following would have a density of 1.89 g/L at 7.0°C and 0.987 atm?