A student combines a solution of NaCl (aq) with a solution of AgNO3 (aq), and a precipitate forms. Which of the following is evidence that ionic bonds formed during the precipitation?
a. The resulting solution is colorless
b. The resulting solution conducts electricity
c. The precipitate has a high melting point
d. The temperature of the solution did not change significantly during the precipitation
The precipitate has a high melting point
The correct answer is c. The precipitate has a high melting point.
The formation of a precipitate during the reaction between NaCl(aq) and AgNO3(aq) is evidence of the formation of ionic bonds. The high melting point of the precipitate is an indication that ionic bonds have formed.
Explanation:
a. The resulting solution is colorless – This does not provide evidence of ionic bond formation. The colorless nature of the solution may be due to the absence of colored ions or the presence of colorless ions.
b. The resulting solution conducts electricity – This is not specific evidence of ionic bond formation. Aqueous solutions of ionic compounds conduct electricity due to the presence of free-moving ions, regardless of whether a precipitation reaction has occurred.
c. The precipitate has a high melting point – This is the correct evidence for ionic bond formation. Ionic compounds, such as the precipitate formed in this reaction (silver chloride, AgCl), have high melting points due to the strong ionic bonds that hold the ions together in a rigid structure. The high melting point is a characteristic property of ionic compounds.
d. The temperature of the solution did not change significantly during the precipitation – While this may be true, it does not provide direct evidence for ionic bond formation. Temperature changes in a reaction depend on various factors, such as the enthalpy of the reaction and the amount of reactants and products involved.
The formation of a precipitate with a high melting point is a strong indication of the formation of ionic bonds between the cations (Ag+) and anions (Cl-) in the reaction between NaCl(aq) and AgNO3(aq).