The following reaction reaches chemical equilibrium in a closed container at 1 000 °C - NSC Physical Sciences - Question 6 - 2016 - Paper 2
Question 6
The following reaction reaches chemical equilibrium in a closed container at 1 000 °C.
2AX₁(g) ⇌ 2AX₂(g) + X₂(g)
The course of reaction is illustrated in the graph... show full transcript
Worked Solution & Example Answer:The following reaction reaches chemical equilibrium in a closed container at 1 000 °C - NSC Physical Sciences - Question 6 - 2016 - Paper 2
Step 1
6.1 Explain the meaning of the term chemical equilibrium.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Chemical equilibrium occurs when the rate of the forward reaction equals the rate of the reverse reaction, resulting in no net change in the concentrations of the reactants and products over time.
Step 2
6.2.1 time the reaction took to reach chemical equilibrium for the first time.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The graph indicates that the reaction reached equilibrium for the first time at 4 minutes.
Step 3
6.2.2 number of moles of AX₃ at the first equilibrium.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
At equilibrium, the number of moles of AX₃ is determined to be 0.5 mol.
Step 4
6.3 Calculate the volume of the container if Kₑ = 2.5 x 10² at 1000 °C.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
To find the volume, we use the equilibrium constant expression:
Kc=[AX1]2[AX2]2[X2]
Substituting known values into the expression and solving yields:
2.5×102=(n/V)2(0.5)2(0.2)
After calculations, the volume of the container is found to be 11.52 L.
Step 5
6.4 Is the yield, HIGH or LOW at 1000 °C? Give a reason.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The yield is LOW at 1000 °C because the equilibrium constant (Kₑ) indicates that the concentration of products is significantly less than that of the reactants at this temperature.
Step 6
6.5 The change in the number of moles at 8 minutes is caused by a DECREASE in temperature.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
This statement is correct; a decrease in temperature shifts the equilibrium to favor the exothermic direction, resulting in a decrease in the number of moles of reactants.
Step 7
6.6 Is the forward reaction ENDOTHERMIC or EXOTHERMIC? Explain your answer by using Le Chatelier's principle.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The forward reaction is ENDOTHERMIC. According to Le Chatelier's principle, when the temperature decreases, the equilibrium will shift towards the side that produces heat, which in this case is the reverse reaction.
Step 8
6.7 What effect will the addition of a suitable catalyst have on the value of Kc? Write down only DECREASES, INCREASES or REMAINS THE SAME.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
REMAINS THE SAME. The addition of a catalyst increases the rate of reaching equilibrium but does not affect the position of equilibrium itself.
