The 5 questions below (a. to e.) are related to the following graph.

The graph below shows the concentrations of the reactants and products for a endothermic reaction under reversible conditions where the reactants and products are all gases.

1. Given the variations of concentration over time depicted in the graph and table above, determine the stoichiometric coefficients for the reversible reaction
   (enter the stoichiometric coefficients as numbers, e.g. if you think the balancing number should be 1 then type "1") [1 mark]
   A (g)  ⇌  B (g)

2. If, at a certain time, the value of the equilibrium constant, K, was 6.67. What would the value of the equilibrium constant be if all the stoichiometric coefficients for the reaction were halved?  [1 mark]
   (give your answer to 3 significant figures):  

3. At each of the times labelled "Time(1)" and "Time(2)" a disturbance was made to the reaction mixture.

   1. Determine what disturbance was made at "Time(1)" [0.5 marks]
      Reactant A was removed from the reaction mixture

      The volume of the reaction mixture was decreased/the pressure of the reaction mixture was increased

      A catalyst was added to the system

      The temperature of the reaction mixture was increased

      Product B was added to the reaction mixture

      Product B was removed from the reaction mixture

      The temperature of the reaction mixture was decreased

      Reactant A was added to the reaction mixture

      The volume of the reaction mixture was increased/the pressure of the reaction mixture was decreased

   2. Determine what disturbance was made at "Time(2)" [0.5 marks]
      The volume of the reaction mixture was increased/the pressure of the reaction mixture was decreased

      The volume of the reaction mixture was decreased/the pressure of the reaction mixture was increased

      The temperature of the reaction mixture was decreased

      The temperature of the reaction mixture was increased

      A catalyst was added to the system

      Product B was removed from the reaction mixture

      Product B was added to the reaction mixture

      Reactant A was added to the reaction mixture

      Reactant A was removed from the reaction mixture

4. How will the value of the equilibrium constant at 10 minutes (K_{10 min}) compare to the value of the equilibrium constant at 6 minutes (K_6 min)?  [1 mark]
   The equilibrium constant at 10 minutes will be
   equal to

   less than

   greater than
   the equilibrium constant at 6 minutes

5. The enthalpy change, Δ_rH, for the forward reaction is +52 kJ mol^-1. The temperature of the system at 10 minutes was 298 K. What was the temperature of the system at 6 minutes?  [1 mark]
   (give your answer to 3 significant figures and in units of K, do not type the units in the answer box):  K

The 5 questions below (a. to e.) are related to the following graph.

The graph below shows the concentrations of the reactants and products for a endothermic reaction under reversible conditions where the reactants and products are all gases.

1. Given the variations of concentration over time depicted in the graph and table above, determine the stoichiometric coefficients for the reversible reaction
   (enter the stoichiometric coefficients as numbers, e.g. if you think the balancing number should be 1 then type "1") [1 mark]
   A (g)  ⇌  B (g)

2. If, at a certain time, the value of the equilibrium constant, K, was 6.67. What would the value of the equilibrium constant be if all the stoichiometric coefficients for the reaction were halved?  [1 mark]
   (give your answer to 3 significant figures):  

3. At each of the times labelled "Time(1)" and "Time(2)" a disturbance was made to the reaction mixture.

   1. Determine what disturbance was made at "Time(1)" [0.5 marks]
      The temperature of the reaction mixture was decreased

      A catalyst was added to the system

      The volume of the reaction mixture was increased/the pressure of the reaction mixture was decreased

      Reactant A was removed from the reaction mixture

      The temperature of the reaction mixture was increased

      The volume of the reaction mixture was decreased/the pressure of the reaction mixture was increased

      Product B was removed from the reaction mixture

      Reactant A was added to the reaction mixture

      Product B was added to the reaction mixture

   2. Determine what disturbance was made at "Time(2)" [0.5 marks]
      Reactant A was removed from the reaction mixture

      Product B was added to the reaction mixture

      The volume of the reaction mixture was decreased/the pressure of the reaction mixture was increased

      A catalyst was added to the system

      The temperature of the reaction mixture was decreased

      Product B was removed from the reaction mixture

      The temperature of the reaction mixture was increased

      Reactant A was added to the reaction mixture

      The volume of the reaction mixture was increased/the pressure of the reaction mixture was decreased

4. How will the value of the equilibrium constant at 10 minutes (K_{10 min}) compare to the value of the equilibrium constant at 6 minutes (K_6 min)?  [1 mark]
   The equilibrium constant at 10 minutes will be
   greater than

   equal to

   less than
   the equilibrium constant at 6 minutes

5. The enthalpy change, Δ_rH, for the forward reaction is +52 kJ mol^-1. The temperature of the system at 10 minutes was 298 K. What was the temperature of the system at 6 minutes?  [1 mark]
   (give your answer to 3 significant figures and in units of K, do not type the units in the answer box):  K

Complete the following sentences by selecting the appropriate selection from the drop down. [5 marks]

This question considers the bonding in the molecule F-C≡P as modelled by valence bond theory - your answers should reflect this.

The hybridisation for the central C atom in this molecule is

The left-most diagram shows the atomic valence orbitals for carbon and their ground state configuration. 

In the middle diagram, Orbital diagram 1: A shows

In the right-most diagram, Orbital diagram 2: C shows 

The most appropriate orbital diagram for C in F-C≡P is

The single bond between the F and C will involve electrons from the C atom in

Complete the following sentences by selecting the appropriate selection from the drop down. [5 marks]

This question considers the bonding in the molecule F-C≡P as modelled by valence bond theory - your answers should reflect this.

The hybridisation for the central C atom in this molecule is

The left-most diagram shows the atomic valence orbitals for carbon and their ground state configuration. 

In the middle diagram, Orbital diagram 1: A shows

In the right-most diagram, Orbital diagram 2: C shows 

The most appropriate orbital diagram for C in F-C≡P is

The single bond between the F and C will involve electrons from the C atom in

The 5 questions below (a. to e.) are related to the following graph.

The graph below shows the concentrations of the reactants and products for a endothermic reaction under reversible conditions where the reactants and products are all gases.

1. Given the variations of concentration over time depicted in the graph and table above, determine the stoichiometric coefficients for the reversible reaction
   (enter the stoichiometric coefficients as numbers, e.g. if you think the balancing number should be 1 then type "1") [1 mark]
   A (g)  ⇌  B (g)

2. If, at a certain time, the value of the equilibrium constant, K, was 6.67. What would the value of the equilibrium constant be if all the stoichiometric coefficients for the reaction were halved?  [1 mark]
   (give your answer to 3 significant figures):  

3. At each of the times labelled "Time(1)" and "Time(2)" a disturbance was made to the reaction mixture.

   1. Determine what disturbance was made at "Time(1)" [0.5 marks]
      Reactant A was removed from the reaction mixture

      The volume of the reaction mixture was decreased/the pressure of the reaction mixture was increased

      A catalyst was added to the system

      The temperature of the reaction mixture was increased

      Product B was added to the reaction mixture

      Product B was removed from the reaction mixture

      The temperature of the reaction mixture was decreased

      Reactant A was added to the reaction mixture

      The volume of the reaction mixture was increased/the pressure of the reaction mixture was decreased

   2. Determine what disturbance was made at "Time(2)" [0.5 marks]
      The volume of the reaction mixture was increased/the pressure of the reaction mixture was decreased

      The volume of the reaction mixture was decreased/the pressure of the reaction mixture was increased

      The temperature of the reaction mixture was decreased

      The temperature of the reaction mixture was increased

      A catalyst was added to the system

      Product B was removed from the reaction mixture

      Product B was added to the reaction mixture

      Reactant A was added to the reaction mixture

      Reactant A was removed from the reaction mixture

4. How will the value of the equilibrium constant at 10 minutes (K_{10 min}) compare to the value of the equilibrium constant at 6 minutes (K_6 min)?  [1 mark]
   The equilibrium constant at 10 minutes will be
   equal to

   less than

   greater than
   the equilibrium constant at 6 minutes

5. The enthalpy change, Δ_rH, for the forward reaction is +52 kJ mol^-1. The temperature of the system at 10 minutes was 298 K. What was the temperature of the system at 6 minutes?  [1 mark]
   (give your answer to 3 significant figures and in units of K, do not type the units in the answer box):  K

A 0.1 M solution of weak acid HA has a pH of 4.70 at 25.0°C.

ii) Calculate the standard free energy change (ΔG°) for the acid dissociation at 25.0°C. ΔG° = kJ mol^-1 at 25 °C. [1 mark]

iii) At 75.0°C, the value of ΔG° is +66.0 kJ mol^-1.  Calculate the entropy change (ΔS°) for the acid dissociation, assuming that both the enthalpy and entropy changes (ΔH° and ΔS°, respectively) are constant over the temperature range considered.

The entropy change is J K^-1 mol^-1 [2 marks]

The reaction kinetics for the reaction between the gases C₂(g) and AB(g) was investigated and the data is presented in the table below:

2C₂(g)  +  2AB(g)  →  A₂(g)  +  2C₂B(g)

1. Complete the rate equation with appropriate values for the rate constant and orders. Only enter numeric values in each box, do not enter units.  [3 marks]

rate = × [C₂][AB]

1. Below are three reaction mechanisms that have been proposed for the reaction between C₂(g) and AB(g). Which mechanism is consistent with the rate law for this reaction? [3 marks]
   1

   2

   3

1. In mechanism 2 above, what is the molecularity of step 1?  [1 mark]
   unimolecular

   bimolecular

   termolecular
    
2. In mechanism 3 above, which step is the rate determining step? [1 mark]
   step 1

   step 2

3. In mechanism 3 above, which species is an intermediate? [1 mark]
   C₂B(g)

   A₂B(g)

   A₂(g)

   AB(g)

   B₂(g)

   C₂(g)
4. In general, if the first step in a mechanism is fast, and the second step is slow, what is the usual approximation made about the first step? [1 mark]
   the second step comes to equilibrium

   the first step comes to equilibrium

   the first step is rate determining

The rate equation for a given reaction with reactants A and B was found to be

r = k[A][B]²

1. The reaction is 2nd order with respect to reactant A

2. The reaction is 1st order with respect to reactant B

3. The reaction is 3rd order overall

4. The units for the rate constant are mol^-2 L² s^–1

Identify which of the following spectra would be

seen by the space telescope through path A.