Question 1

The concentration of carbon monoxide in a sample of air is 9.2 ppm.There are ________ molecules of CO in 1.00 L of this air at 755 torr and 23°C.

Accepted Answer

The answer of The concentration of carbon monoxide in a...

Question 2

The mole fraction of carbon dioxide in dry air near sea level is 0.000375,where the molar mass of carbon dioxide is 44.010.The partial pressure of carbon dioxide when the total atmospheric pressure (dry air)is 97.5 kPa is ________ kPa.

Accepted Answer

The answer of The mole fraction of carbon dioxide in...

Question 3

A 0.600 g sample containing Ag₂O and inert material is heated,causing the silver oxide to decompose according to the following equation: 2 Ag₂O(s)→ 4 Ag(s)+ O₂(g) If 13.8 mL of gas are collected over water at 27°C and 1.00 atm external pressure,what is the percentage of silver oxide in the sample? The partial pressure of water is 26.7 mm Hg at 27°C.

Accepted Answer

First, we need to calculate the moles of gas collected using the ideal gas law:

PV = nRT

n = (PV)/(RT)
n = ((1.00 atm)(0.0138 L))/(0.08206 L·atm/mol·K)(300 K)
n = 0.000668 mol

Next, we can use the balanced equation to find the moles of Ag2Sb12O:

2 Ag2Sb12O --> 4 Ag + O2
1 mol Ag2Sb12O produces 1/2 mol O2
0.000668 mol O2 * (1 mol Ag2Sb12O / 1/2 mol O2) = 0.001336 mol Ag2Sb12O

Finally, we can calculate the percentage of Ag2Sb12O in the sample:

mass of sample = mass of Ag2Sb12O + mass of inert material
mass of Ag2Sb12O = n × MM × (molar ratio of Ag2Sb12O in sample) 
MM of Ag2Sb12O = (2 × 107.87 g/mol) + 121.76 g/mol + 15.99 g/mol × 12 = 2383.3 g/mol
molar ratio of Ag2Sb12O in sample = 1 mol Ag2Sb12O / 4 mol Ag
mass of Ag2Sb12O = 0.001336 mol × 2383.3 g/mol × (1/4) = 0.0799 g

% Ag2Sb12O = (mass of Ag2Sb12O / total mass of sample) × 100%
% Ag2Sb12O = (0.0799 g / 0.600 g) × 100%
% Ag2Sb12O = 13.32%

Since the question asks for the percentage of silver oxide (Ag2O) in the sample, we need to note that Ag2O was converted to Ag during the decomposition reaction. Therefore, the percentage of Ag2O in the sample is twice the percentage of Ag2Sb12O:

% Ag2O = 2 × % Ag2Sb12O
% Ag2O = 2 × 13.32%
% Ag2O ≈ 26.6%

The closest answer choice is C, 41.8%, but none of the answer choices are exact.

Question 4

What is the total pressure in a 6.00-L flask which contains 0.127 mol of H₂(g)and 0.288 mol of N₂(g)at 20.0°C?

Accepted Answer

To solve this problem, we need to use the ideal gas law: 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. First, we need to calculate the total number of moles of gas in the flask: n(total) = n(H₂) + n(N₂) n(total) = 0.127 mol + 0.288 mol n(total) = 0.415 mol Next, we need to convert the volume of the flask to liters (it's given in milliliters): V = 6.00 L We also need to convert the temperature to Kelvin (add 273.15 to the Celsius temperature): T = 20.0°C + 273.15 T = 293.15 K Now we can plug in the numbers and solve for P: P = nRT/V P = (0.415 mol)(0.0821 L·atm/mol·K)(293.15 K)/(6.00 L) P = 1.66 atm Therefore, the answer is D) 1.66 atm.

Question 5

A gas occupies 22.4 L at STP and 19.0 L at 100°C and 1.50 atm pressure.How many moles of gas did the system gain or lose?

Accepted Answer

The answer of A gas occupies 22.4 L at STP...

Question 6

The mole fraction of oxygen in dry air near sea level is 0.20948.The concentration of oxygen is ________ molecules per liter,assuming an atmospheric pressure of 739 torr and a temperature of 29.5°C.

Accepted Answer

The answer of The mole fraction of oxygen in dry...

Question 7

Zinc reacts with aqueous sulfuric acid to form hydrogen gas: Zn(s)+ H₂SO₄(aq)→ ZnSO₄(aq)+ H₂(g) In an experiment,201 mL of wet H₂ is collected over water at 27°C and a barometric pressure of 733 torr.The vapor pressure of water at 27°C is 26.74 torr.The partial pressure of hydrogen in this experiment is ________ atm.

Accepted Answer

The answer of Zinc reacts with aqueous sulfuric acid to...

Question 8

A 1.44-g sample of an unknown pure gas occupies a volume of 0.335 L at a pressure of 1.00 atm and a temperature of 100.0°C.The unknown gas is ________.

Accepted Answer

Using the combined gas law, we can calculate the number of moles of gas present:
P1V1/T1 = P2V2/T2
(1.00 atm)(0.335 L)/(373.15 K) = P2(0.335 L)/(298.15 K)
P2 = 1.22 atm
Then, we can use the ideal gas law to calculate the molar mass, which we can use to identify the gas:
PV = nRT
(1.22 atm)(0.335 L) = n(0.08206 L atm/mol K)(298.15 K)
n = 0.0142 mol
Molar mass = (1.44 g)/(0.0142 mol) = 101.45 g/mol
The closest match on the periodic table is xenon, which has a molar mass of 131.29 g/mol. Therefore, the unknown gas is likely xenon.

Question 9

Which of the following would have a density of 1.37 g/L at 7.0°C and 0.987 atm?

Accepted Answer

The gas that has a density of 1.37 g/L at 7.0°C and 0.987 atm is most likely to be oxygen (O2), which has a molecular mass of 32. Therefore, using the ideal gas law,

PV = nRT

n/V = P/RT

The molar volume of the gas at these conditions would be:

(V/n) = RT/P = (0.08206 L⋅atm/mol⋅K)(280 K)/(0.987 atm) = 23.2 L/mol

The density of the gas would be:

d = m/V = (m/M)/(V/n) = (1.37 g/L)/(32 g/mol)/(23.2 L/mol) = 0.00183 mol/L

Therefore, the gas is most likely to be oxygen (O2), which has a density of 1.43 g/L at 7.0°C and 0.987 atm.

Question 10

A 0.286-g sample of gas occupies 125 mL at 60.cm of Hg and 25°C.What is the molar mass of the gas?

Accepted Answer

The first step is to use the ideal gas law to find the number of moles of gas present:

PV = nRT

where P = 60 cmHg = 80 kPa (using the conversion factor 1 atm = 101.3 kPa), V = 125 mL = 0.125 L, R = 8.31 J/(mol·K), and T = 25°C + 273 = 298 K.

n = PV/RT = (80 kPa)(0.125 L)/(8.31 J/(mol·K)·298 K) = 0.00480 mol

The molar mass can then be calculated using the formula:

molar mass (g/mol) = mass (g) / number of moles

molar mass (g/mol) = 0.286 g / 0.00480 mol = 59.6 g/mol

Therefore, the best choice is D, 71 g/mol, which is the closest answer choice to 59.6 g/mol. Keep in mind that the calculated value may differ slightly due to rounding errors or the use of different values for constants like R or the conversion factor for pressure units.

Question 11

A balloon contains 0.76 mol N₂,0.18 mol O₂,0.031 mol He and 0.026 mol H₂ at 749 mm Hg.What is the partial pressure of O₂?

Accepted Answer

The answer of A balloon contains 0.76 mol N₂,0.18 mol...

Question 12

The concentration of ozone in a sample of air that has a partial pressure of O₃ of 0.33 torr and a total pressure of air of 735 torr is ________ ppm.

Accepted Answer

The concentration of ozone in ppm is given by:ppm = (Partial pressure of O3 / Total pressure of air) * 10^6ppm = (0.33 torr / 735 torr) * 10^6ppm = 4.5 × 10^2

Question 13

The density of chlorine gas at 1.21 atm and 34.9°C is ________ g/L.

Accepted Answer

Using the ideal gas law, PV = nRT, we can rearrange it to solve for density:
density = (P * M) / (R * T), where P is pressure, M is molar mass, R is the gas constant, and T is temperature.
First, we need to find the molar mass of chlorine, which is 35.5 g/mol.
Then, we can plug in the values and solve for density:
density = (1.21 atm * 35.5 g/mol) / (0.0821 L*atm/mol*K * 307.05 K) = 3.39 g/L, which is answer choice E.

Question 14

In the laboratory,hydrogen gas is usually made by the following reaction: Zn(s)+ 2 HCl(aq)→ H₂(g)+ ZnCl₂(aq) How many liters of H₂ gas,collected over water at an atmospheric pressure of 752 mm Hg and a temperature of 21.0°C,can be made from 3.566 g of Zn and excess HCl? The partial pressure of water vapor is 18.65 mm Hg at 21.0°C.

Accepted Answer

The answer of In the laboratory,hydrogen gas is usually made...

Question 15

The concentration of water vapor in a sample of air that has a partial pressure of water of 0.91 torr and a total pressure of air of 735 torr is ________ ppm.

Accepted Answer

The concentration in ppm is calculated by (partial pressure of water vapor / total pressure) × 10^6. Thus, (0.91 / 735) × 10^6 = 1.2 × 10^3 ppm.

Question 16

Zinc reacts with aqueous sulfuric acid to form hydrogen gas: Zn(s)+ H₂SO₄(aq)→ ZnSO₄(aq)+ H₂(g) In an experiment,225 mL of wet H₂ is collected over water at 27°C and a barometric pressure of 748 torr.How many grams of Zn have been consumed? The vapor pressure of water at 27°C is 26.74 torr.

Accepted Answer

We can use the ideal gas law to calculate the amount of hydrogen gas produced, and then use stoichiometry to find the amount of zinc consumed. First, we need to correct the collected gas volume to its volume at standard temperature and pressure (STP), which is 0°C and 1 atm of pressure:
V(STP) = (225 mL) * [(760-26.74) torr / 748 torr] * (273 K / (273+27) K) = 204.4 mL
Next, we can use the ideal gas law to calculate the number of moles of hydrogen gas produced:
PV = nRT
n = PV/RT = (1 atm) * (0.2044 L) / [(0.08206 L*atm/(mol*K)) * (300 K)]
n = 0.00851 mol
Finally, we can use the stoichiometry of the balanced chemical equation to find the number of moles of zinc consumed, and then convert to grams using the molar mass of zinc:
1 mol Zn : 1 mol H2
x mol Zn : 0.00851 mol H2
x = 0.00851 mol Zn
m(Zn) = n(Zn) * M(Zn) = (0.00851 mol) * (65.38 g/mol) = 0.556 g Zn
Therefore, the answer is B) 0.567 g (rounded to three significant figures).

Question 17

The mole fraction of argon in dry air near sea level is 1.818 × 10^-5 where the molar mass of argon is 39.948.The concentration of argon in the atmosphere is ________ ppm.

Accepted Answer

The mole fraction of argon is equivalent to its concentration in ppm, so 1.818 × 10^-5 is equal to 18.18 ppm.

Question 18

Given three cylinders containing O₂ gas at the same volume and pressure.Cylinder A is at -15°C,cylinder B is at -5°F,cylinder C is at 255 K.Which cylinder contains the largest mass of oxygen?

Accepted Answer

The answer of Given three cylinders containing O₂ gas at...

Question 19

What is the density of hydrogen gas at STP?

Accepted Answer

The density of hydrogen gas at STP (standard temperature and pressure) is 0.0899 g/L. This value can be obtained by using the ideal gas law, which states that PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the universal gas constant, and T is the temperature. At STP, the pressure is 1 atm and the temperature is 0°C (273.15 K). The molar mass of hydrogen gas is 2.016 g/mol. Therefore, we can calculate the density as follows:

PV = nRT
n = PV/RT = (1 atm) (1 L) / (0.0821 L·atm/mol·K) (273.15 K)
n = 0.0409 mol

The mass of one mole of hydrogen gas is 2.016 g/mol. Therefore, the mass of 0.0409 mol of hydrogen gas is:

0.0409 mol × 2.016 g/mol = 0.0825 g

Finally, we can divide the mass by the volume (1 L) to get the density:

density = mass/volume = 0.0825 g / 1 L = 0.0899 g/L

Therefore, the best choice is D.

Question 20

A sample of air from a home is found to contain 6.2 ppm of carbon monoxide.This means that if the total pressure is 695 torr,then the partial pressure of CO is ________ torr.

Accepted Answer

ppm (parts per million) is a unit of concentration. 6.2 ppm means there are 6.2 parts of CO for every 1,000,000 parts of air. Therefore, the partial pressure of CO is equal to the total pressure of air in the sample multiplied by the concentration of CO in ppm.

Partial pressure of CO = total pressure x (concentration of CO / 1,000,000)

Partial pressure of CO = 695 torr x (6.2 / 1,000,000)

Partial pressure of CO = 4.3 x 10^-3 torr

Therefore, the answer is choice B).

Quiz 5: Gases

The concentration of carbon monoxide in a sample of air is 9.2 ppm.There are ________ molecules of CO in 1.00 L of this air at 755 torr and 23°C.

The mole fraction of carbon dioxide in dry air near sea level is 0.000375,where the molar mass of carbon dioxide is 44.010.The partial pressure of carbon dioxide when the total atmospheric pressure (dry air) is 97.5 kPa is ________ kPa.

What is the total pressure in a 6.00-L flask which contains 0.127 mol of H₂(g) and 0.288 mol of N₂(g) at 20.0°C?

A gas occupies 22.4 L at STP and 19.0 L at 100°C and 1.50 atm pressure.How many moles of gas did the system gain or lose?

The mole fraction of oxygen in dry air near sea level is 0.20948.The concentration of oxygen is ________ molecules per liter,assuming an atmospheric pressure of 739 torr and a temperature of 29.5°C.

A 1.44-g sample of an unknown pure gas occupies a volume of 0.335 L at a pressure of 1.00 atm and a temperature of 100.0°C.The unknown gas is ________.

Which of the following would have a density of 1.37 g/L at 7.0°C and 0.987 atm?

A 0.286-g sample of gas occupies 125 mL at 60.cm of Hg and 25°C.What is the molar mass of the gas?

A balloon contains 0.76 mol N₂,0.18 mol O₂,0.031 mol He and 0.026 mol H₂ at 749 mm Hg.What is the partial pressure of O₂?

The concentration of ozone in a sample of air that has a partial pressure of O₃ of 0.33 torr and a total pressure of air of 735 torr is ________ ppm.

The density of chlorine gas at 1.21 atm and 34.9°C is ________ g/L.

The concentration of water vapor in a sample of air that has a partial pressure of water of 0.91 torr and a total pressure of air of 735 torr is ________ ppm.

The mole fraction of argon in dry air near sea level is 1.818 × 10^-5 where the molar mass of argon is 39.948.The concentration of argon in the atmosphere is ________ ppm.

Given three cylinders containing O₂ gas at the same volume and pressure.Cylinder A is at -15°C,cylinder B is at -5°F,cylinder C is at 255 K.Which cylinder contains the largest mass of oxygen?

What is the density of hydrogen gas at STP?

A sample of air from a home is found to contain 6.2 ppm of carbon monoxide.This means that if the total pressure is 695 torr,then the partial pressure of CO is ________ torr.

Quiz 5: Gases

The concentration of carbon monoxide in a sample of air is 9.2 ppm.There are ________ molecules of CO in 1.00 L of this air at 755 torr and 23°C.

The mole fraction of carbon dioxide in dry air near sea level is 0.000375,where the molar mass of carbon dioxide is 44.010.The partial pressure of carbon dioxide when the total atmospheric pressure (dry air) is 97.5 kPa is ________ kPa.

What is the total pressure in a 6.00-L flask which contains 0.127 mol of H2(g) and 0.288 mol of N2(g) at 20.0°C?

A gas occupies 22.4 L at STP and 19.0 L at 100°C and 1.50 atm pressure.How many moles of gas did the system gain or lose?

The mole fraction of oxygen in dry air near sea level is 0.20948.The concentration of oxygen is ________ molecules per liter,assuming an atmospheric pressure of 739 torr and a temperature of 29.5°C.

A 1.44-g sample of an unknown pure gas occupies a volume of 0.335 L at a pressure of 1.00 atm and a temperature of 100.0°C.The unknown gas is ________.

Which of the following would have a density of 1.37 g/L at 7.0°C and 0.987 atm?

A 0.286-g sample of gas occupies 125 mL at 60.cm of Hg and 25°C.What is the molar mass of the gas?

A balloon contains 0.76 mol N2,0.18 mol O2,0.031 mol He and 0.026 mol H2 at 749 mm Hg.What is the partial pressure of O2?

The concentration of ozone in a sample of air that has a partial pressure of O3 of 0.33 torr and a total pressure of air of 735 torr is ________ ppm.

The density of chlorine gas at 1.21 atm and 34.9°C is ________ g/L.

The concentration of water vapor in a sample of air that has a partial pressure of water of 0.91 torr and a total pressure of air of 735 torr is ________ ppm.

Zinc reacts with aqueous sulfuric acid to form hydrogen gas: Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g) In an experiment,225 mL of wet H2 is collected over water at 27°C and a barometric pressure of 748 torr.How many grams of Zn have been consumed? The vapor pressure of water at 27°C is 26.74 torr.

The mole fraction of argon in dry air near sea level is 1.818 × 10-5 where the molar mass of argon is 39.948.The concentration of argon in the atmosphere is ________ ppm.

Given three cylinders containing O2 gas at the same volume and pressure.Cylinder A is at -15°C,cylinder B is at -5°F,cylinder C is at 255 K.Which cylinder contains the largest mass of oxygen?

What is the density of hydrogen gas at STP?

A sample of air from a home is found to contain 6.2 ppm of carbon monoxide.This means that if the total pressure is 695 torr,then the partial pressure of CO is ________ torr.

What is the total pressure in a 6.00-L flask which contains 0.127 mol of H₂(g) and 0.288 mol of N₂(g) at 20.0°C?

A balloon contains 0.76 mol N₂,0.18 mol O₂,0.031 mol He and 0.026 mol H₂ at 749 mm Hg.What is the partial pressure of O₂?

The concentration of ozone in a sample of air that has a partial pressure of O₃ of 0.33 torr and a total pressure of air of 735 torr is ________ ppm.

The mole fraction of argon in dry air near sea level is 1.818 × 10^-5 where the molar mass of argon is 39.948.The concentration of argon in the atmosphere is ________ ppm.

Given three cylinders containing O₂ gas at the same volume and pressure.Cylinder A is at -15°C,cylinder B is at -5°F,cylinder C is at 255 K.Which cylinder contains the largest mass of oxygen?