Gas Laws and Partial Pressure
What are the 6 gas laws, including the ideal gas law?
-P1V1/n1T1=P2V2/n2T2
-V1/T1=V2/T2
-P1/T1=P2/T2
-P1V1=P2V2
-V1/n1=V2/n2
Ideal Gas Law
-PV=nRT where R= 0.0821 L*atm/mol*K
What are the 5 postulates of KME?
Treat all particles in a gas as point masses (gases have negligible volume which essentially means they don't have any volume compared to the empty space between them)
Constant random motion (travel in a straight line unless they collide with another particle or the container itself)
All collisions are elastic (energy is not lost as heat, only transferred)
No intermolecular forces (gases are independent of each other, and do not attract/repel each other. They act independently).
The average kinetic energy of a particle in a gas is proportional to temperature (All gases at the same temp have the same Ke)
What are the definitions of endothermic and exothermic respectively? Give an example of each
Endothermic: In terms of the system, gains heat from the surroundings (positive change) (Ice cube melting)
Exothermic: In terms of the system, loses heat to the surroundings (negative change) (Steam condensing to droplets)
You would like to raise the temperature of two metals of equal mass but different heat capacities by 14 ˚C each. Which metal requires the larger input of heat to produce that temperature change?
The metal with the higher heat capacity.
Define frequency, amplitude and wavelength. What are the relationships between them?
Amplitude: how high peaks are
Frequency: how many peaks in a given frame of time
Wavelength: how far apart peaks are from each other
Energy is proportional to frequency, but inversely proportional to wavelength
A 60.0 L welding gas cylinder at a temperature of 27.2 °C contains 30.7 moles of carbon dioxide gas and 92.0 moles of argon gas and has a total pressure of 50.4 atm. What is the partial pressure of argon in the cylinder?
37.8 atm
What is the equation used to find a gas' velocity? Name the R constant, what the temperature has to be in and the units of molar mass.
sqrt(3RT/MM)
R= 8.314 J/Mol K and molar mass is in kg/mol and T in K
What would be the signs on q and w that represent a system that is doing work on the surroundings, as well as losing heat to the surroundings?
a. q = -, w = -
Q14C
-80 kJ
Which would have the lowest energy photon?
633nm, 514 nm, 248 nm, 308nm, 647 nm
647 nm
A sample of Ar gas at 35°C occupies a volume of 1.50 L at a pressure of 3.2 atm. How many moles of the gas are present in the sample?
0.190 moles
Consider 3 moles of Helium gas in a sealed balloon.Temperature is kept constant, and the volume of the balloon is observed to shrink to half of its original volume. What must have happened to the pressure?
The pressure increased by a factor of two
Which of the following phase changes are EXOTHERMIC:
Freezing, melting, vaporization, condensation
Freezing and condensation
Q15C
-4018 kJ
One of the ultraviolet spectral lines emitted from a hydrogen lamp is found at 103 nm. What is the energy of a single photon from this transition?
1.93 × 10^-18 J
The density of an ideal gas depends on what two factors?
The temperature and pressure of the gas sample and the molar mass of the gas sample
Which of the following ideal gases will move the fastest at 400 K?
N2, O2, CO2
N2
What is the change in internal energy (ΔE) when a system is heated with 35 J of energy while it expands against an external pressure doing 15 J of work?
+20J
When 25.0 mL of aqueous solution A is mixed with 25.0 mL of aqueous solution B in a coffee-cup calorimeter, the final temperature of the 50.0 mL mixture is 3.0 ℃ higher than the initial temperature. Calculate qrxn. (Assume the specific heat of the solution is 4.184 J/g °C, and the density of the solution is 1.00 g/mL)
-628 J
What is the frequency of a photon whose wavelength is 525 nm?
5.71 X 10^14 Hz
What mass of Ag2O(s) (in grams) is required to form 0.388 L of oxygen gas at P = 0.965 atm and T = 298 K? The molar mass of Ag2O is 231.74 g/mol.
2 Ag2O(s) → 4 Ag(s) + O2(g)
7.10 g
Which of the following conditions is the ideal gas law least likely to work well and explain why.
High temp, low pressure; high temp, high pressure; low temp, low pressure; low temp, high pressure
Low temp, high pressure. Ideal gas law needs high temp and low pressure. Low temp creates non-elastic collisions because they are more likely to stick together and have attraction, which ideally, they wouldn't
Higher enthalpy. Absorbed.
Magnesium sulfate is often used in hand-warmer packets. Suppose that 0.0166 moles of MgSO4 is added to some water at 21 °C in a coffee-cup calorimeter to give 17.0 g of aqueous solution, and that the temperature of the solution rises to 42.2 °C upon addition of the magnesium sulfate. What is ΔH for the reaction in kJ/mol? Assume that the heat capacity of the resulting solution is the same as that of water, Cs = 4.184 J/(g°C).
-90.8 kJ/mol
Calculate the frequency of the red light emitted by a neon sign with a wavelength of 690 nm.
4.35 × 10^14 s-1