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When is a reversible reaction said to be at chemical equilibrium?
AForward and reverse rates are zero
BForward and reverse rates are equal
CAll the reactants have been used up
DThe forward rate is much larger
Answer & Solution
Correct answer: B. Forward and reverse rates are equal
1. In a reversible reaction the products can turn back into the reactants.
2. As the reactants run down the forward reaction slows, and as products build up the reverse reaction speeds up.
3. Eventually the two rates become equal and the amounts of reactant and product stop changing.
4. That balance point is what is meant by chemical equilibrium.
_Source: Siyavula Physical Sciences Grade 12 (Everything Science, CC BY 4.0), Chapter 8: Chemical equilibrium_
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