Molarity
Calculate the molarity of a solution containing 9.00 mol of ethanol (C₂H₅OH) dissolved in enough water to make 2.25 L of solution.
4.00M
A reaction occurring in a flask releases 725 J of heat to the surroundings, and the gas produced performs 380 J of work on the surroundings by expanding against a piston. Determine ΔU and ΔH for this reaction.
ΔH = -725J
ΔU = -1105J
True or false: Molecular collisions are inelastic; that is, energy is lost when molecules colide.
False
What happens to the total pressure in a sealed container as this reaction goes to completion?
N₂(g) + 3 H₂(g) → 2 NH₃(g)
a) The pressure increases.
b) The pressure decreases.
c) Initially the pressure increases, then it returns to the original pressure.
d) The pressure does not change.
e) Initially the pressure decreases, then it returns to the original pressure.
b) The pressure decreases.
What does increasing n do to an electron?
a) Changes shape
b) Increases energy and size
c) Changes spin
b) Increases energy and size
If 18.0 g of KOH is added to 250.0 mL of water, what is the resulting concentration (molarity) of the solution?
1.28M
A chemical reaction is carried out in a piston-cylinder apparatus. The initial volume of the system is 0.800 L, and the final volume is 0.500 L. The pressure remains constant at 1.20 atm. Determing the work done (in Joules) during this process.
36.5 J
A 2.10 L sample of nitrogen gas (N₂) has a pressure of 1.20 atm. What is its volume after the pressure is changed to 0.855 atm, assuming constant temperature?
2.95 L
A container holds a mixture of gases at a total pressure of 1.20 atm. The partial pressure of nitrogen gas (N₂) is 0.50 atm, and the partial pressure of oxygen gas (O₂) is 0.30 atm. What is the partial pressure of carbon dioxide (CO₂) in the container?
0.40 atm
If the first two quantum numbers for an electron are n = 4 and ℓ = 1, which energy level and subshell does that electron occupy?
4p (energy level 4, subshell p)
What volume of a 0.300 M Na₂SO₄ solution is required to react exactly with 45.0 mL of a 0.200 M BaCl₂ solution?
Reaction: Na2SO4 + BaCl2 → BaSO4 + 2NaCl
.0300L or 30.0mL
A 60.0 g sample of an unknown metal is heated to 95.0°C and then placed into 200.0 g of water at 18.0°C. The final temperature of the system is 22.8°C.
What is the specific heat capacity (c) of the metal?
0.927 J/g°C
A sample of gas is collected over water at 25.0°C. The total pressure of the gas mixture is 742 Torr, and the volume of the collected gas is 3.10 L. What is the partial pressure of the dry gas in the container?
718 torr (or mmHg)
If a sample of oxygen gas (O₂) at 300 K and a pressure of 1.25 atm has a volume of 4.80 L, what will the volume be if the temperature is increased to 350 K and the pressure is decreased to 0.900 atm?
7.78L
For: n = 4, ℓ = 2, mℓ = −1
What subshell?
Is this a valid orbital?
subshell - d
Calculate the molar mass of an unknown alkali hydroxide if it took 42.10 mL of 0.985 M HNO₃ to neutralize 30.00 mL of a solution of the base that contained 2.450 g of the pure metal hydroxide.
59.08 g/mol
Calculate ΔH for the reaction:
2 NO₂(g) → N₂O₄(g)
Given the following equations and enthalpies:
N₂(g) + 2 O₂(g) → 2 NO₂(g) ΔH = +66.4 kJ
N₂(g) + 2 O₂(g) → N₂O₄(g) ΔH = +9.6 kJ
-56.8kJ
What is the temperature of a sample of oxygen gas (O₂) that has a density of 1.30 g/L and a pressure of 1.20 atm?
360 K
A gas with the formula SOₓ is found to effuse at a rate that is 0.756 times the rate of effusion of oxygen gas (O₂). Determine (a) the molar mass of SOₓ and
(b) the value of x?
Mm = 56.0 g/mol
x = 1.5
Which set is NOT possible, and why?
a) n = 3, ℓ = 2, mℓ = 2
b) n = 2, ℓ = 1, mℓ = −1
c) n = 1, ℓ = 1, mℓ = 0
d) n = 4, ℓ = 3, mℓ = −3
c) n = 1, ℓ = 1, mℓ = 0
because ℓ must be 0 only when n=1 (range = 0...n-1) and can therefore only be 0
If 22.5 mL of a 0.350 M calcium hydroxide, Ca(OH)₂, solution is required to neutralize 10.0 mL of a nitric acid (HNO₃) solution, what is the concentration of the acid?
Reaction: Ca(OH)2 + 2HNO3 → Ca(NO3)2 + 2H2O
1.58M
Calculate the standard enthalpy change (ΔH°rxn) for the following reaction:
C₂H₆(g) + 7/2 O₂(g) → 2 CO₂(g) + 3 H₂O(l)
Given the standard enthalpies of formation (ΔH°f):
CO₂(g) = −393.5 kJ/mol
H₂O(l) = −285.8 kJ/mol
C₂H₆(g) = −84.7 kJ/mol
O₂(g) = 0.0 kJ/mol
-1560kJ
Determine the volume of O₂(g) produced when 85.0 g of KClO₃ (molar mass = 122.55 g/mol) decomposes at 1.00 atm and 300 K according to the reaction:
2 KClO₃(s) → 2 KCl(s) + 3 O₂(g)
25.6 L
A 2.00 L mixture of helium, krypton, and xenon has a total pressure of 745 mmHg at 310 K. If the partial pressure of helium is 255 mmHg and the partial pressure of krypton is 185 mmHg, what mass of xenon is present in the mixture?
4.14 g
An electron has the following quantum numbers:
n = 4, ℓ = 2, mℓ = −2, mₛ = +½
Identify the energy level, subshell, and determine how many orbitals exist in this subshell.
- energy level: 4
- subshell: d
- Number of orbitals: 5