Unit 3: Intermolecular Forces
Unit 5: Kinetics
Unit 7: Equilibrium
100
What are the different types of IMFs?
London-Dispersion forces, Dipole-dipole, Ion-dipole, and hydrogen attractive forces.
100
The two diagrams above represent collisions that take place at the same temperature between a CO molecule and an NO2 molecule. The products are CO2 and NO. Which diagram most likely represents an effective collision, and why?
Diagram 1 represents an effective collision because the two molecules have the proper orientation to form a new C−O bond as long as they possess enough energy to overcome the activation energy barrier.
100
Define equilibrium
A state of a reaction where the rate of the forward reaction is equal to the rate of the reverse reaction. (Must mention rates and may mention net 0 change.)
200
A solid compound of a group 1 (alkali) metal and a group 17 (halogen) element dissolves in water. The diagram above represents one type of solute particle present in the solution. Identify the solute particle and explain how the solute particle interacts with water molecules.
The particle is a positive ion, and the interactions are ion-dipole attractions.
200
The diagram above shows the distribution of molecular collision energies for equimolar samples of a reactant at different temperatures. Based on the diagram, at which temperature will the reactant be consumed at the fastest rate, and why?
At T4, because a larger fraction of the molecules have an energy that is equal to or greater than the activation energy.
200
Equation 1:2NO2(g)⇄N2O4(g) K1
Equation 2:N2O4(g)⇄2NO2(g) K2
What can be used to determine the value of K2?
The value of K1
300
The structures of two allotropes of carbon are represented above. Explain why diamond is much harder than graphite?
Diamonds are a covalent network solid while graphite is a molecular solid. Carbon atoms in diamond have four covalent bonds, whereas graphite is made of layers that are held together by relatively weak dispersion forces.
300
The concentration of N2O5 was measured over time. The following graphs were created using the data.
Based on the graphs above, what is the order of the reaction with respect to N2O5 ?
First order
300
2SO2(g)+O2(g)⇄2SO3(g) Kp≈2×105
At a certain temperature, SO2(g) and O2(g) react to produce SO3(g) according to the chemical equation shown above. An evacuated rigid vessel is originally filled with SO2(g) and O2(g), each with a partial pressure of 1atm. Find the partial pressure of O2(g) after the system has reached equilibrium, and explain why that is?
~0.5atm; because Kp is very large, nearly all the SO2(g) is consumed before the system reaches equilibrium, but an excess amount of O2(g) remains at equilibrium
400
The diagram above shows thin-layer chromatograms of the same mixture of two compounds. Based on the chromatograms, which solvent would be most effective at separating the two compounds if the same stationary phase is used for column chromatography?
Solvent C
400
Step 1:H2O2+I−→IO−+H2OStep 2:H2O2+IO−→H2O+O2+I−
The mechanism for a chemical reaction is shown above. Which of the following statements about the overall reaction and rate laws of the elementary reactions is correct?
The chemical equation for the overall reaction is 2 H2O2→2 H2O+O2, and the rate law for elementary step 1 is rate=k[H2O2][I−].
400
When 0.0322 mol of NO and 1.70 g of bromine are placed in a 1.00 L reaction vessel and sealed, the mixture reacts and the following equilibrium is established:
2NO(g) + Br2(g) ⇌ 2NOBr(g)
At 25.0 °C the equilibrium of nitrosyl bromide is 0.438 atm. What is the Kp?
Kp = 38.2
500
A gaseous air‑fuel mixture in a sealed car engine cylinder has an initial volume of 600.mL at 1.0atm. To prepare for ignition of the fuel, a piston moves within the cylinder, reducing the volume of the air‑fuel mixture to 50.mL at constant temperature. Assuming ideal behavior, what is the new pressure of the air‑fuel mixture?
About 12atm, because the volume of the gas mixture decreased by a factor of 12.
500
Zn(s)+2 HCl(aq)→ZnCl2(aq)+H2(g)
Zn(s) reacts with HCl(aq) according to the equation shown above. In trial 1 of a kinetics experiment, a 5.0g piece of Zn(s) is added to 100mL of 0.10MHCl(aq). The rate of reaction between Zn(s) and HCl(aq) is determined by measuring the volume of H2(g) produced over time. In trial 2 of the experiment, 5.0g of powdered Zn(s) is added to 100mL of 0.10MHCl(aq). Which trial will have a faster initial rate of reaction and why?
Trial 2, because the sample of Zn(s) has a greater surface area for the reaction to take place.
500
Consider the reaction:
H2 + I2 ⇌ 2HI
whose Keq = 54.8. If an equimolar mixture of the reactants gives the concentration of the product to be 0.500 M at equilibrium, determine the concentration of hydrogen.
0.0675 M