Chemistry

Correct answer: a) the direct and reverse reactions continue to occur.

Step-by-step solution:

1. **Understand the concept of chemical equilibrium**: A system is in chemical equilibrium when the rates of the direct and reverse reactions are equal. This means that, although the reactions continue to occur, the concentrations of reactants and products remain constant over time.

2. **Analyzing the alternatives**:
   - a) **the direct and reverse reactions continue to occur**: This is the definition of chemical equilibrium. The reactions do not stop but occur at equal rates, maintaining the concentrations of reactants and products constant.
   - b) the direct reaction stops: This is not true because if the direct reaction stopped, the reverse reaction would continue until all products were converted back to reactants, which is not a state of equilibrium.
   - c) the reverse reaction stops: This is also not true for the same reason that alternative b is incorrect.
   - d) the sum of the concentrations of a and b must be equal to the sum of the concentrations of c and d: This is not necessarily true. The concentrations of reactants and products at equilibrium depend on the equilibrium constants and do not need to be equal.
   - e) the direct and reverse reactions stop: This is incorrect because at equilibrium, the reactions do not stop; they occur at equal rates.

3. **Choose the correct alternative**: Based on the understanding of chemical equilibrium, the only alternative that correctly describes the state of equilibrium is alternative a), as it states that the direct and reverse reactions continue to occur, which is the defining characteristic of a system in chemical equilibrium.

When the system $$A+B \rightleftharpoons C+D$$ is at equilibrium:

Question about Chemical Equilibrium

Subject Chemistry

Chemistry

Topic Chemical Equilibrium

Chemical Equilibrium

Difficulty Easy

Easy

(UFAM 2022) - Question Easy of Chemistry