Question 1

Which of the following best describes a precipitation reaction?

Accepted Answer

A reaction in which ions in solution combine to form an insoluble compound that separates from the solution.

Question 2

When aqueous solutions of silver nitrate ($AgNO_3$) and sodium chloride ($NaCl$) are mixed, what is the net ionic equation for the reaction?

Accepted Answer

$Ag^+(aq) + Cl^-(aq) \rightarrow AgCl(s)$

Question 3

Which of the following compounds will form a precipitate when mixed with a solution of $AgNO_3$?

Accepted Answer

$KCl$

Question 4

A student mixes solutions of $Pb(NO_3)_2$ and $NaI$. What is the formula of the precipitate formed?

Accepted Answer

$PbI_2$

Question 5

Which ions are considered spectator ions in the reaction between $AgNO_3(aq)$ and $NaCl(aq)$?

Accepted Answer

$Na^+$ and $NO_3^-$

Question 6

You are given two colorless solutions: one contains $BaCl_2$ and the other contains $BaI_2$. Which reagent would you use to distinguish between them, and what observation would you expect?

Accepted Answer

Add $AgNO_3$; $BaCl_2$ forms a white precipitate, $BaI_2$ forms a pale yellow precipitate.

Question 7

Which of the following best explains, in terms of intermolecular forces (IMF), why $AgCl$ precipitates from solution when $AgNO_3$ and $NaCl$ are mixed?

Accepted Answer

The ionic bonds in $AgCl$ are stronger than the ion-dipole attractions with water, so $AgCl$ is insoluble.

Question 8

Which of the following is the correct complete ionic equation for the reaction between $Pb(NO_3)_2(aq)$ and $NaI(aq)$?

Accepted Answer

$Pb^{2+}(aq) + 2NO_3^-(aq) + 2Na^+(aq) + 2I^-(aq) \rightarrow PbI_2(s) + 2Na^+(aq) + 2NO_3^-(aq)$

Question 9

A solution contains $Ba^{2+}$ and $Cl^-$ ions. Which of the following reagents would you add to test for the presence of $Cl^-$, and what would you observe?

Accepted Answer

Add $AgNO_3$; a white precipitate forms.

Question 10

Which of the following best describes the role of solubility rules in predicting precipitation reactions?

Accepted Answer

They allow prediction of which combinations of ions will form an insoluble compound (precipitate).

Question 11

Which of the following is the net ionic equation for the reaction of hydrochloric acid with nickel carbonate?

Accepted Answer

$2H^+(aq) + NiCO_3(s) \rightarrow Ni^{2+}(aq) + H_2O(l) + CO_2(g)$

Question 12

A laboratory technician needs to distinguish between $BaCl_2(aq)$, $SrCl_2(aq)$, and $NaCl(aq)$. Which single reagent and observation would allow all three to be distinguished?

Accepted Answer

Add $Na_2SO_4$; $BaCl_2$ and $SrCl_2$ form white precipitates, $NaCl$ does not.

Question 13

Which of the following statements about spectator ions is correct?

Accepted Answer

Spectator ions remain unchanged and do not participate in the overall reaction.

Question 14

A solution of $KOH$ is mixed with a solution of $Pb(NO_3)_2$. What is the precipitate formed, and what is its formula?

Accepted Answer

$Pb(OH)_2$

Question 15

Which of the following best explains why $NaNO_3$ does not precipitate when $AgNO_3$ and $NaCl$ are mixed?

Accepted Answer

$NaNO_3$ is highly soluble in water due to strong ion-dipole interactions.

Question 16

Which of the following combinations will NOT result in a precipitate?

Accepted Answer

$Na_2SO_4(aq)$ and $KNO_3(aq)$

Question 17

A student adds $AgNO_3$ to an unknown solution and observes a creamy yellow precipitate. Which anion is most likely present?

Accepted Answer

$I^-$

Question 18

Which of the following is a correct molecular equation for the reaction between $AgNO_3(aq)$ and $NaCl(aq)$?

Accepted Answer

$AgNO_3(aq) + NaCl(aq) \rightarrow AgCl(s) + NaNO_3(aq)$

Question 19

In a real-world scenario, why might a doctor use a precipitation reaction in a medical test?

Accepted Answer

To detect the presence of specific ions in a patient's blood by observing the formation of a precipitate.

Precipitation Reactions and Ionic Equations in Aqueous Solutions

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