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The following equipment was set up and the reaction allowed to proceed - HSC - SSCE Chemistry - Question 34 - 2012 - Paper 1
Question 34
The following equipment was set up and the reaction allowed to proceed. Gases were produced at both electrodes. Name this process and identify the gas at each elect... show full transcript
Worked Solution & Example Answer:The following equipment was set up and the reaction allowed to proceed - HSC - SSCE Chemistry - Question 34 - 2012 - Paper 1
Step 1
Name this process and identify the gas at each electrode.
Answer
The process described is electrolysis. At electrode P (anode), chlorine gas (Cl₂) is produced due to the oxidation of chloride ions (Cl⁻). At electrode Q (cathode), hydrogen gas (H₂) is produced from the reduction of water or sodium ions.
Step 2
Step 3
Calculate the equilibrium constant for this reaction and use this value to describe the position of the equilibrium.
Answer
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First, we find the concentrations at equilibrium:
- Initial concentration of NO = 0.400 mol in 1.00 L = 0.400 mol L⁻¹.
- Given that [N₂] = 0.198 mol L⁻¹, and since the stoichiometry indicates that 2 moles of NO produce 1 mole of N₂ and 1 mole of O₂, we can derive the concentration of O₂.
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From the balanced equation, we find:
- Hence, [O₂] will also be 0.198 mol L⁻¹.
- The change in concentration for NO due to these products will be: 0.400 - 2(0.198) = 0.004 mol L⁻¹.
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Therefore, the equilibrium constant K is: [ K = \frac{[N_2][O_2]}{[NO]^2} = \frac{(0.198)(0.198)}{(0.004)^2} = 2450.5 ]
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A larger K value indicates that the position of equilibrium favors the products (N₂ and O₂).
Step 4
What could be changed that would result in a different value of K for this equilibrium?
Answer
The equilibrium constant K for a reaction is dependent on temperature. Changing the temperature of the reaction can shift the position of equilibrium, thus resulting in a different K value. Additionally, altering concentrations or adding inert gases can affect the concentration of products and reactants but will not change the value of K itself.