Chapter 6 (6.5-6.10): Gases
Use the molar volume of a gas at STP to determine the volume (in L) occupied by 27.2 g of argon at STP.
15.3 L
If energy flows out of a chemical system and into the surroundings, what is the sign of ΔEsys? If energy flows in?
When energy flows out of the system into the surroundings, ΔEsys is negative. When energy flows into the system and out of the surroundings, ΔEsys is positive.
A system releases 511 kJ of heat and does 125 kJ of work on the surroundings. What is the change in internal energy of the system?
-636 kJ
Calculate the total energy in 1.5 x 10¹³ photons of gamma radiation having λ = 3.0 x 10⁻¹² m.
1.0 J
A sample of argon effuses from a container in 112 seconds. The same amount of an unknown noble gas requires 79.6 seconds. Identify the second gas.
Neon
Which of the following is a state function?
Temperature
Heat
Temperature
When you stir a cup of tea, you do about 0.050 J of work each time you circle the spoon in the cup. How many times would you have to stir the spoon to heat a 0.15-kg cup of tea by 2.0°C? (Use the specific heat capacity of water, 4.184 J/g•°C)
2.6 × 10⁴ stirs
The wavelength of green light from a traffic signal is centered at 5.20 x 10⁻⁵ cm. Calculate the frequency.
5.77 × 10¹⁴ Hz
A gas mixture contains 1.05 g N2 and 1.35 g O2 in a 1.35-L container at 15°C. Calculate the mole fraction and partial pressure of each component in the gas mixture.
𝛘N2 = 0.470
𝛘O2 = 0.530
PN2 = 0.656 atm
PO2 = 0.739 atm
Which of the following is a not state function?
Pressure
Work
Enthalpy
Work
A piece of metal weighing 59.047 g was heated to 100.0 °C and then put it into 100.0 mL of water (initially at 23.7 °C). The metal and water were allowed to come to an equilibrium temperature, determined to be 27.8 °C. Assuming no heat lost to the environment, calculate the specific heat capacity of the metal.
0.402 𝐽/𝑔•°𝐶
What are the types of electromagnetic radiation in order of frequency?
Radio, Microwave, Infrared, Visible, Ultraviolet, X-Ray, Gamma
A gas mixture contains each of the following gases at the indicated partial pressures:
N2, 111 torr
O2, 213 torr
He, 102 torr
What is the total pressure of the mixture? What mass of each gas is present in a 1.55-L sample of this mixture at 25.0°C?
Ptot = 426 torr
0.259 g N2
0.568 g O2
0.0340 g He
Which of the following processes is endothermic?
Melting
Condensing
Melting
Zinc metal reacts with hydrochloric acid according to the balanced equation:
Zn (𝑠) + 2 HCl (𝑎𝑞) → ZnCl2 (𝑎𝑞) + H2(𝑔)
When 0.103 g of zinc is combined with enough HCl to make 50.0 mL of solution in a coffee-cup calorimeter, all of the zinc reacts, raising the temperature of the solution from 22.5 °C to 23.7 °C. Find ΔHrxn for this reaction as written. (Use 1.0 g/mL for the density of the solution and 4.18 𝐽/𝑔•°𝐶 as the specific heat capacity.)
-159 kJ/mol
Sketch and label each of the four types of orbitals
s, p, d, and f orbital shapes are in the October 22nd Lecture PowerPoint (Slide 37)
Consider a 1.0-L sample of helium gas and a 1.0-L sample of argon gas, both at room temperature and atmospheric pressure.
Do the atoms in the helium sample have the same average kinetic energy as the atoms in the argon sample? If not, which is higher?
Do the atoms in the helium sample have the same average velocity as the atoms in the argon sample? If not, which is higher?
Do the argon atoms, because they are more massive, exert a greater pressure on the walls of the container?
Which gas sample has the faster rate of effusion?
The helium and argon atoms have the same average kinetic energy.
The average velocity of helium is higher, with a root mean square velocity that is 10 times that of argon.
No. Even though the argon atoms are more massive than the helium atoms, both have the same kinetic energy at a given temperature. Therefore, the argon atoms have a lower velocity, moving more slowly and exerting the same pressure as the helium atoms.
Helium has a faster rate of effusion.
Which of the following represents and exothermic reaction?
ΔH = -560 kJ
ΔH = 73 J
ΔH = -560 kJ
Hydrazine (N2H4) is a fuel used by some spacecraft. It is normally oxidized by N2O4 according to the equation:
N2H4 (𝑙)+ N2O4 (𝑔) → 2 N2O (𝑔) + 2 H2O (𝑔)
Calculate ΔH°rxn for this reaction using standard enthalpies of formation
-380.2 kJ/mol
List the possible values of n, l, and ml for each of the following subshells
2s
4f
3p
1s
n = 2; l = 0; ml = 0
n = 4; l = 3; ml = -3, -2, -1, 0, 1, 2, 3
n = 3; l = 1; ml = -1, 0, 1
n = 1; l = 0; ml = 0