Question

1. a student adds a 1g sample of an unknown, brittle solid to distilled water, stirs the mixture, and then measures its conductivity. the student repeats this procedure with more samples of the unknown solid and then produces the graph above. which of the following statements about the graph and the properties of the solid is correct? a. the increase in conductivity indicates that the unknown is an ionic solid that dissociates into ions when it dissolves in water. b. the increase in conductivity indicates that the unknown is a network covalent solid that ionizes in water. c. the straight - line plot indicates that the unknown solid is infinitely soluble in water. d. the straight - line plot indicates that the unknown solid has a very low solubility in water. 24. which of the diagrams above best represents the interactions that are responsible for the relatively large solubility of kcl crystals in water, and why? a. diagram 1, because strong ion - dipole interactions between kcl and water help to dissociate the solute. b. diagram 1, because strong london dispersion forces between the k+ and cl− ions and water replace the weak london dispersion forces between two water molecules. c. diagram 2, because strong dipole - dipole forces between kcl and water help to separate the kcl units within the crystals. d. diagram 2, because the hydrogen bonds between water molecules expand to accommodate the kcl particles and pull them into solution.

Explanation:

For question 23: Ionic solids dissociate into ions in water, which increases conductivity. Network - covalent solids do not ionize in water. A straight - line plot of conductivity vs mass added does not directly indicate solubility (infinite or low).
For question 24: KCl is an ionic compound. In water, strong ion - dipole interactions between the ions of KCl ($K^+$ and $Cl^-$) and the polar water molecules help to dissociate the solute.

Answer:

1. A. The increase in conductivity indicates that the unknown is an ionic solid that dissociates into ions when it dissolves in water.
2. A. Diagram 1, because strong ion - dipole interactions between KCl and water help to dissociate the solute.