Question

tdsb.elearningontario.ca
consists only of a reverse reaction
consists of both a forward and a reverse reaction
consists of neither a forward nor a reverse reaction
none of the above
question 2 (1 point)
a system has reached chemical equilibrium. which is true of the system?
there is no net change in the concentration of reactants or products
the molecules have stopped combining and decomposing
the system is open
there is no change taking place
all of the above are true
question 3 (1 point)
which does not remain constant when a system is at dynamic equilibrium?
pressure
molecular reactions
temperature

Explanation:

• Question 2: At chemical equilibrium, the forward and reverse reaction rates are equal. So, there is no net change in the concentration of reactants or products. Molecules do not stop combining and decomposing (the reaction is dynamic), and for a system to reach equilibrium, it is usually a closed system (not open).
• Question 3: At dynamic equilibrium, pressure and temperature remain constant (assuming no external changes). But molecular reactions (the forward and reverse reactions) are still occurring (they are just balanced in terms of rate), so molecular reactions do not “remain constant” in the sense of being stopped.

Answer:

• Question 2: there is no net change in the concentration of reactants or products
• Question 3: molecular reactions