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Moderate

Changing Concentrations During A Titration

APCHEM-6VGTFE

A titration is carried out by slowly adding a solution of 0.125 M $NaOH(aq)$, in 1-mL increments, to a flask containing 25.00 mL of a solution of ${H}_{2}S{O}_{4}(aq)$. The titration continues until the equivalence point is reached, as shown by phenolphthalein indicator.

Which of the following CORRECTLY describes the change in the concentration of sodium ions, $\left[ { Na }^{ + } \right] $, and the concentration of sulfate ions, $\left[ S{ O }_{ 4 }^{ 2– } \right] $, in the flask during the titration?

A

$\left[ { Na }^{ + } \right]$ and $\left[ S{ O }_{ 4 }^{ 2– } \right]$ both increase.

B

$\left[ { Na }^{ + } \right]$ increases, but $\left[ S{ O }_{ 4 }^{ 2– } \right]$ decreases.

C

$\left[ { Na }^{ + } \right]$ increases, but $\left[ S{ O }_{ 4 }^{ 2– } \right]$ remains the same.

D

$\left[ { Na }^{ + } \right]$ and $\left[ S{ O }_{ 4 }^{ 2– } \right]$ both decrease.