Gasses
Thermochemistry
Stoichiometry
Chemical Bonding
Miscellaneous
100
At what temperature does 16.3 g of nitrogen gas have a pressure of 1.25 atm in a 25.0 L tank?
655 K
100
What is enthalpy of formation? Give an example reaction demonstrating enthalpy of formation (a value of ΔH is not needed).
The enthalpy change occurs when 1 mole of the substance is formed from its constituent elements in their standard states
H2 + O2 → ½ H2O
100
Balance the following:
_Cu + _HNO3 → _Cu(NO3)2 + _NO + _H2O
3Cu + 8HNO3 → 3Cu(NO3)2 + 2NO + 4H2O
100
Draw the structures for HCN, including formal charges.
H-C≡N: (no formal charges)
H-N≡C: (+1 on N and -1 on C)
100
Rank the following intermolecular forces in terms of strength:
Dipole-dipole, London Dispersion Forces, and Hydrogen Bonds
LDF < Dipole-Dipole < Hydrogen Bonding
200
A 2.50 L volume of hydrogen measured at –196 °C is warmed to 100 °C. Calculate the volume of the gas at the higher temperature, assuming no change in pressure.
12.1 L
200
What does each variable in the equation q=mcΔT represent, and what are their units?
q: heat, J
m: mass, g
c: specific heat, J/g°C
T: temperature, °C
200
A 25.00 mL sample of 0.146 M HCl is mixed with 10.00 mL of 0.189 M Mg(OH)2. Will the final solution have a pH greater than, less than, or equal to 7?
Greater than 7 (more OH- than H+)
200
Give the electron configuration for Fe.
[Ar] 3d⁶ 4s²
200
What are the answers to the following:
1. 432.5 mL - 24.3984 mL =
2. 246 m x 1.5 m =
3. 3.85 x 10-18 / 7.35 x 10-36 =
1. 408.1 mL
2. 370 m2
3. 5.24 x 1017
300
Many assumptions allow the Ideal Gas Law to be applied. Describe two of them.
1. Gas particles have negligible volume
2. Gas particles have negligible IMFs
3. Gas particles undergo perfectly elastic collisions
4. All molecules of a given gas are identical
300
5.0 mL of ethanol (d = 0.789 g/mL) at 8.0°C is mixed with 55.0 mL of water at 28.2°C. Assuming no heat is lost, what is the final temperature of the mixture?
T= 21.8°C
300
Suppose 316.0 g of aluminum sulfide reacts with 493.0 g of water in the following fashion:
Al2S3 + H2O ---> Al(OH)3 + H2S
What mass of the excess reactant is left after the reaction?
Mass of water: 265.5 g
300
What properties make a good Lewis structure?
1. All atoms follow the octet rule
2. Formal charges are minimized
3. Maximized charge separation
300
Explain the periodic trends for electronegativity, ionization energy, and atomic radius.
Electronegativity: increases up and to the right; more protons in nucleus and less shells
Ionization energy: increases up and to the right; greater ENC and less shells
Atomic Radii: Increases down and to the left; lower ENC and more shells
400
A mixture containing 1.0 mol H2(g), 7.0 mol N2(g), and 2.0 mol O2(g) exerts a total pressure of 1.5 atm. What are the partial pressures of all three gasses?
H2: 0.15 atm
N2: 1.05 atm
O2: 0.30 atm
400
Calculate the standard heat of formation for ClF + F2 ⟶ CLF3
2OF2 ⟶ O2 + 2F2 ΔH°=-49.4kJ/mol
2ClF + O2 ⟶ Cl2O + OF2 ΔH°=205.6 kJ/mol
ClF3 + O2 ⟶ ½Cl2O + 
OF2 ΔH°=266.7 kJ/mol
ΔH°=-139.2 kJ/mol
400
12.915 g of a biochemical substance containing only carbon, hydrogen, and oxygen was burned in an atmosphere of excess oxygen. Subsequent analysis of the gaseous result yielded 18.942 g carbon dioxide and 7.749 g of water. Determine the empirical formula of the substance.
CH2O
400
Draw the correct structure for SF5- and give its electron arrangement and molecular geometry.
Electron arrangement: Octahedral
Geometry: Square pyramidal
400
What are the quantum numbers for chlorine?
n = 3
l = 1
m = -1, 0, 1
s = -½ or ½
500
A balloon carries 40.0 gallons of liquid propane (density 0.5005 g/L). What volume of CO2 and H2O gas is produced by the combustion of this propane at STP?
270 L
500
An 11.0 g sample of CaCl2 is dissolved in 125 g of water, with both substances at 25°C. Calculate the final temperature of the solution assuming no heat loss to the surroundings and assuming the solution has a specific heat capacity of 4.18 J/g°C.
CaCl2(s) → Ca2+(aq) + 2Cl-(aq) ΔH= -81.5 kJ/mol
T= 39.2°C
500
Balance the following in basic solution:
Pb2+ + IO3- → PbO2 + I2
8OH- + 5Pb2+ + 2IO3- → 5PbO2 + I2 + 4H2O
500
Give the correct molecular geometry, bond angle around the central atom, and hybridization for the following molecules:
CO2, H2S, and SbCl4-
CO2: linear, 180°, sp
H2S: bent, <109.5°, sp3
SbCl4-: seesaw, 90° and 120°, sp3d
500
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