Question 21 to 22.
Q21) Calculate the change in internal energy of a system that absorbs 10kJ of heat and does 2kJ of work.
( A) 8kJ (B) 12kJ (C) 20kJ (D) -12kJ
Q22) For an equilibrium to be established, one of the following must always hold. (A) r_{f}=1(B)\mathfrak{n}=1(\mathbb{C})r_{f}=n_{b}(D)\cdot
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Q21) The change in internal energy of a system can be calculated using the formula:
ΔU = Q - W
where ΔU is the change in internal energy, Q is the heat absorbed by the system, and W is the work done by the system.
In this case, Q = 10 kJ and W = 2 kJ. Substituting these values into the formula:
ΔU = 10 kJ - 2 kJ
ΔU = 8 kJ
Therefore, the change in internal energy of the system is 8 kJ. Answer choice (A) 8 kJ is correct.
Q22) For an equilibrium to be established, the forward reaction rate must equal the reverse reaction rate. This can be represented using the reaction rate constants:
r_f = kf * [A] * [B]
r_b = kb * [C] * [D]
where r_f is the forward reaction rate, r_b is the reverse reaction rate, kf and kb are the rate constants, and [A], [B], [C], [D] are the concentrations of the reactants and products.
Therefore, the correct statement is:
(A) r_f = 1
This means that the forward reaction rate is equal to 1. Answer choice (A) is correct.