Consider the balanced equation for a hypothetical reaction that takes place in 2 dm³ sealed containers - NSC Physical Sciences - Question 6 - 2024 - Paper 2
Question 6
Consider the balanced equation for a hypothetical reaction that takes place in 2 dm³ sealed containers.
P₂(g) + 3Q(s) ⇌ 2P₂Q(g)
The graphs below, not drawn to scal... show full transcript
Worked Solution & Example Answer:Consider the balanced equation for a hypothetical reaction that takes place in 2 dm³ sealed containers - NSC Physical Sciences - Question 6 - 2024 - Paper 2
Step 1
6.1 State 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
Le Chatelier's principle states that if a system at equilibrium is subjected to a change in concentration, temperature, or pressure, the system will adjust itself to counteract that change and re-establish equilibrium.
Step 2
6.2 What do the parallel lines after t = 5 minutes in graph A represent?
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 parallel lines after t = 5 minutes in graph A indicate that the concentrations of the reactants and products remain constant, suggesting that the system has reached equilibrium.
Step 3
6.3 Is the forward reaction EXOTHERMIC or ENDOTHERMIC?
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
The forward reaction is EXOTHERMIC, as indicated by the decreasing concentration of the product with increasing temperature.
Step 4
6.4 Explain the answer to QUESTION 6.3.
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
In an exothermic reaction, increasing the temperature shifts the equilibrium position to favor the reactants, thereby decreasing the concentration of the products. This is consistent with Le Chatelier's principle.
Step 5
6.5 How does the value of the equilibrium constant, Kc, for the reaction in graph A compare to that in graph B? Choose from GREATER THAN, LESS THAN or EQUAL TO.
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 value of the equilibrium constant, Kc, for the reaction in graph A is LESS THAN that in graph B, due to the differences in temperature affecting the equilibrium position.
Step 6
6.6 The equilibrium constant, Kc, is 0.49 at 398 K (graph B). Calculate the initial number of moles of P₂Q.
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
Using the equilibrium expression:
Kc=[P2][Q]3[P2Q]2
At 398 K, the concentrations at equilibrium were 0.35 mol·dm⁻³ for P₂Q. Therefore, the initial number of moles of P₂Q is calculated using the formula:
6.7 Describe the change made to the equilibrium system at t = 8 minutes, as shown in graph B, at a constant temperature.
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
At t = 8 minutes, the graph B shows an increase in the concentration of P₂Q, suggesting that some of the products may have been removed or that the system has adjusted to the addition of more reactants, favoring the forward reaction.
Step 8
6.8 Explain by using Le Chatelier's principle how the system reacts to the change in QUESTION 6.7.
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
According to Le Chatelier's principle, if the concentration of the products is decreased, the system will shift to the right in an attempt to produce more products. Thus, when P₂Q is increased, the equilibrium shifts right, favoring the formation of products.
