Chemistry 101 Week 12
Which of the following states that the total pressure of a mixture of ideal gases is equal to the sum of the partial pressures of the component gases? Select the correct answer below: Charles's Law Dalton's Law Boyle's Law Gay-Lussac's Law
Correct answer: Dalton's Law Dalton's law states that the total pressure of a mixture of ideal gases is equal to the sum of the partial pressures of the component gases. The pressure that each individual gas exerts in a mixture is known as partial pressure, and it would be the same if it were the only gas present in a container.
PV=nRT is the equation for: Select the correct answer below: Amontons's law Charles's law Boyle's law Ideal Gas law
Correct answer: Ideal Gas law The ideal gas law (PV=nRT) incorporates all of the following relationships: Boyle's Law (P×V), Amontons's Law (PT), Charles's Law (VT), and Avogadro's law (Vn). These laws are combined to determine the relationship between pressure, volume, temperature, and number of moles in the ideal gas law.
hich of the following is NOT a unit of pressure? Select the correct answer below: atmosphere, atm Pascal, Pa Newton, N Torr, torr
Correct answer: Newton, N The newton is a unit of force, not a unit of pressure. However, since pressure is a measure of the force applied over an area, the newton is a component of the SI unit for pressure, the pascal. One pascal is equal to one newton per square meter. 1 Pa=N m2
How is a pascal defined in terms of other units? Select the correct answer below: N×m Nm2 m2N Nm
Correct answer: Nm2 Recall that pressure is defined as the force applied over an area perpendicular to it; therefore, pressure is measured in units of force per area. The SI unit for pressure is the pascal, which will be expressed in SI units of force and length. Pa=Nm2
According to kinetic molecular theory, pressure exerted by a gas is due to __________. Select the correct answer below: collisions between the gas molecules and the container walls the gas molecules being negligibly small inelastic collisions between gas molecules all of the above
Correct answer: collisions between the gas molecules and the container walls A force is generated each time a gas particle collides and bounces off the wall of a container. The forces generated by gas particle collisions with the walls of a container result in gas pressure (force applied over the area of the container's walls).
Volume and temperature (in Kelvin) of an ideal gas are __________. Select the correct answer below: directly proportional inversely proportional identical depends on the gas
Correct answer: directly proportional For any gas sample at constant pressure, as its temperature increases, the volume will also increase.
If the volume of a gas is kept constant and the temperature (in Kelvin) is doubled, the pressure will __________. Select the correct answer below: double quadruple be cut in half be cut in one fourth
Correct answer: double Since the temperature and pressure of a sample of ideal gas at constant volume are directly proportional, if one of the quantities doubles, the other must also double.
According to Charles's law, as volume increases, temperature __________. Select the correct answer below: increases stays the same decreases fluctuates
Correct answer: increases According to Charles's law, as volume increases, temperature increases. Charles's law states that the volume of a given amount of gas is directly proportional to its temperature on the Kelvin scale when pressure is constant. This can be seen in V1T1=V2T2.
A large flexible balloon contains 3.5moles of pure nitrogen gas at 1.0atm pressure and 0∘C. What is the volume of the balloon? Round to two significant figures. Provide your answer below:
Correct answers:78 L Notice that 1.0atm pressure and 0∘C are the conditions of standard pressure and temperature (STP). One mole of an ideal gas has a volume of about 22.4L at STP. Therefore, to calculate the volume of nitrogen gas, multiply the number of moles of nitrogen by 22.4Lmol. 3.5mol×22.4Lmol=78.4L Therefore, after rounding to two significant figures, we find that the volume of the balloon is about 78L.
How many pascals are in 1 in Hg? Select the correct answer below: 760 1,000 3,386 101.325
Correct answer: 3,386 The correct conversion from inches of Hg to pascals is, 1 in Hg=3,386 Pa It should be noted that 1 atm=760 torr, and 1 atm=101.325 kPa. Also, 1,000 Pa=1 kPa. Your answer: 101.325
Who is credited with first establishing the relationship between volume and pressure at constant temperature? Select the correct answer below: Guillaume Amontons Jacques Charles Gay-Lussac Robert Boyle
Correct answer: Robert Boyle Robert Boyle is credited with first establishing the relationship between volume and pressure at constant temperature. According to Boyle's law, the volume of a given amount of gas held at constant temperature is inversely proportional to its pressure. If the volume of a gas was to decrease, the pressure would increase, and if the volume of a gas was to increase, the pressure would decrease. This can be seen in P1V1=P2V2.
Which plot will give a straight line? Select the correct answer below: V vs. P V vs. 1P 1V vs. 1P V vs. ln(P)
Correct answer: V vs. 1P Boyle's law states P1V1=P2V2. Thus, volume and pressure are inversely related, so only the reciprocal of the pressure against volume results in a linear plot.
On the Kelvin scale, 0 is known as __________. Select the correct answer below: sub-zero dependent zero absolute zero none of the above
Correct answer: absolute zero On the Kelvin scale, 0 is known as absolute zero. All gas law calculations require that temperatures be on the Kelvin scale. Absolute zero implies that the kinetic energy of all molecules is zero as well.
If the pressure of a gas is kept constant and the temperature (in Kelvin) is cut in half, the volume will __________. Select the correct answer below: double quadruple be cut in half be cut in one fourth
Correct answer: be cut in half Since pressure and temperature are directly proportional according to Charles's law, if one is cut in half, the other must also be halved. Your answer: quadruple According to Charles's law, the volume and temperature of a gas (in degrees Kelvin) are directly proportional. If one increases, the other one will increase as well (and the same for decrease). In this case, since the temperature decreases, the volume will decrease as well.
A mixture of gases has 0.333 moles of CO and 0.257 moles of He and 0.401 moles of H2. Which gas will exert the most pressure? Select the correct answer below: carbon monoxide helium hydrogen Not enough information to predict.
Correct answer: hydrogen Without having to calculate each individual pressure, it is possible to know that the gas present in the largest molar amount will exert the most pressure. This is because the ideal gas law is dependent on the moles of gas present; therefore, hydrogen will have the greatest partial pressure since it has the most moles in the mixture, 0.401 moles.
According to Boyle's law, as the volume of a gas decreases the pressure __________. Select the correct answer below: increases stays the same decreases fluctuates
Correct answer: increases According to Boyle's law, as the volume of a gas decreases the pressure increases. The volume of a given amount of gas held at constant temperature is inversely proportional to its pressure. This can be seen in P1V1=P2V2.
If a collision is said to be elastic, it means __________. Select the correct answer below: the pressure stays constant some kinetic energy is lost as a result of the collision no kinetic energy is lost as a result of the collision gas molecules exert no attractive or repulsive forces on each other or the container walls
Correct answer: no kinetic energy is lost as a result of the collision An elastic collision is one in which no energy is lost; both particles continue along their trajectories with the same total kinetic energy as before the collision.
A 50.0 L container holds 45.0 moles of gas. The temperature of the container is 200.∘C. What is the pressure? Use R=0.08206L atm/mol K for the gas constant. Use −273.15∘C for absolute zero. Select the correct answer below: 23.7 atm 34.9 atm 41.8 atm 50.6 atm
Correct answer: 34.9 atm Recall that the equation describing the pressure, volume, amount, and temperature of a gas is the ideal gas law: PV=nRT, where P is the pressure of the gas in atm, V is the volume of the gas in L, n is the amount of gas in mol, T is the temperature of the gas in K, and R is the ideal gas constant, 0.08206L atmmol K. First, convert the temperature into K: T=200.∘ C+273.15 K=473.15 K Next, rearrange the ideal gas law to solve for P: P=nRTV Last, substitute in the known values and solve: P=(45.0 mol)(0.08206L atmmol K)(473.15 K)50.0 L=34.944 atm The answer should have three significant figures, so round to 34.9 atm.
According to KMT, if the temperature of a gas is increased, there will only be a constant pressure if the volume increases. If this occurs, there will be a decrease in the frequency of collisions with the container walls. What gas law is KMT explaining? Select the correct answer below: Dalton's law Avogadro's law Boyle's law Charles's law
Correct answer: Charles's law This describes Charles's law. As the temperature increases, the kinetic energy of the molecules increases, causing an increase in the force exerted upon a collision with the container's wall, leading to an increase in pressure. The volume of the gas must thereby become larger in order to decrease the frequency of the collisions, thus, maintaining a constant pressure.
What is the pressure that each individual gas exerts in a mixture known as? Select the correct answer below: individual pressure incomplete pressure partial pressure all of the above
Correct answer: partial pressure In a mixture of ideal gases that do not react chemically with each other, the individual gases do not affect each other's pressure. Each individual gas in such a mixture exerts the same pressure that it would exert if was alone in the container. The pressure exerted by each individual gas in a mixture is called its partial pressure. This observation is summarized by Dalton's law of partial pressures: the total pressure of a mixture of ideal gases is equal to the sum of the partial pressures of the unmixed component gases. Ptotal=PA+PB+PC+⋯=∑iPi In the equation Ptotal is the total pressure of a mixture of gases, PA is the partial pressure of gas A; PB is the partial pressure of gas B; PC is the partial pressure of gas C; and so on.
The average kinetic energy of gas molecules is proportional to __________. Select the correct answer below: pressure temperature volume molecular weight
Correct answer: temperature A higher temperature means more heat energy can be transferred into kinetic energy of motion and, therefore, greater kinetic energy.
The total pressure of a mixture of gases is equal to: Select the correct answer below: the sum of the partial pressures the product of the partial pressures the difference of two partial pressures the quotient of two partial pressures
Correct answer: the sum of the partial pressures To get the total pressure of a mixture of gases, we add up the partial pressures of each individual gas present in the mixture. This is Dalton's Law, and it is expressed by the following summation: Ptotal=PA+PB+PC+⋯=∑iPi In the equation Ptotal is the total pressure of a mixture of gases, PA is the partial pressure of gas A; PB is the partial pressure of gas B; PC is the partial pressure of gas C; and so on.
The pressure in a tire is 1.90 atm at 25∘C. If the temperature is increased to 35∘C, what will the new pressure be in atmospheres? Use −273.15∘C for absolute zero. Your answer should have three significant figures. Provide your answer below:
Correct answers:$1.96\text{ atm}$1.96 atm Recall that the relationship between the pressure and temperature of a quantity of gas at a fixed volume is P1T1=P2T2. Before we can do anything else, we need to convert both temperatures into K. T1=25∘C+273.15 K=298.15 KT2=35∘C+273.15 K=308.15 K Rearrange the equation to solve for P2 and substitute in the known values. P2=P1T2T1=(1.90 atm)(308.15 K)298.15 K=1.9637 atm The answer should have three significant figures, so round to 1.96 atm.
Calculate the number of moles of H2 in 11L of gas at STP. Your answer should have two significant figures. Provide your answer below:
Correct answers:0.49 mol 1mol of gas occupies a volume of about 22.4L at STP, so the number of moles in 11L can be found by multiplying by a conversion factor. 11L×1mol22.4L=0.4911mol The answer should have two significant figures, so round to 0.49mol.
How many atoms of helium are in 53.1L of He at STP? Use NA=6.022×1023mol−1 for Avogadro's number. Your answer should have three significant figures. Report your answer using scientific notation.
Correct answers:1.43×1024 atoms One mole of any gas at STP has a volume of 22.4L. So first determine the number of moles of gas you have 53.1L22.4L/mol=2.370mol One mole of a substance contains Avogadro's number of particles, or 6.022×1023atoms for a monoatomic gas like helium. Multiply the number of moles by the number of atoms per mole:2.370mol×6.022×1023atomsmol=1.427×1024atomsThe answer has three significant figures, so round to 1.43×1024atoms.
A 2.0 L balloon full of air is at 25.00∘C. What will be the volume of the balloon if it is placed in the freezer at −4.00∘C? Assume ideal gas behavior. Use −273.15∘C for absolute zero. Round the answer to two significant figures. Provide your answer below:
Correct answers:1.8 L First, write the equation for Charles's law V1T1=V2T2 Rearrange this equation to solve for V2 and substitute the given values to solve for the unknown volume. V2=V1T2T1=2.0 L×269.15K298.15K=1.805 L Therefore, after rounding to two significant figures, we find that the volume of the balloon is approximately equal to 1.8L.
What is the partial pressure in atmospheres of N2, if a mixture has 5.0 moles of CO2, 3.0 moles of N2, and 1.0 mole of H2? The container has a total volume of 5.73 L at room temperature of 25.00∘C. Your answer should have two significant figures (round your answer to the nearest whole number). Use R=0.08206 L atm/mol K
Correct answers:13 atm Recall that a mixture of gases will behave independently, so the partial pressure of each gas can be determined from the ideal gas equation, using P=nRTV To calculate the partial pressure of N2, first, you have to convert celsius to kelvin: 25.00∘C+273.15 K=298.15 K Next, substitute in known values and solve. PN2=(3.0 mol)×(0.08206 L atm/mol K)×(298.15 K)5.73 L=12.8 atm The answer should have two significant figures, so round to 13 atm.
What is the standard molar volume of an ideal gas? Round your answer to the nearest tenth. Provide your answer below:
Correct answers:22.4 L/mol There are approximately 22.4 liters per mole of an ideal gas. This number is useful enough that it should be memorized, but it can also be calculated from the ideal gas law: V=nRTP=1 mol⋅0.08206L atmmol K⋅273.15K1 atm≈22.4L
A pure sample of unknown gas has a mass of 147g and a volume of 103L at STP. What is its molecular mass? Your answer should have three significant figures. Provide your answer below:
Correct answers:32.0 g/mol One mole of an ideal gas has a volume of about 22.4L at standard temperature and pressure. Divide the volume of 103L by 22.4L/mole to find the number of moles. Then divide the given mass by the number of moles to obtain the molar mass. 103L22.4L/mole=4.6moles 147g4.6moles=31.97g/mole Your answer should have three significant figures, so round to 32.0g/mol. The unknown gas could be oxygen.
What volume will 30.0g of methane gas (CH4) occupy at STP? Round the answer to three significant figures. Recall that one mole of a gas at STP will have a volume of 22.4L Provide your answer below:
Correct answers:41.9 L First, find the number of moles of methane by dividing the given mass by the molar mass of methane. 30.0g×1mol16.043g=1.870mol One mole of a gas at STP will have a volume of 22.4L1.870mol×22.4L1mol=41.89L.Rounding to three significant figures gives 41.9L.
