http://www.ck12.org Chapter 15. Water
- Water is able to dissolve many ionic compounds because of the attraction between the polar water molecules
and the ions in the crystal lattice. Water can also dissolve some solid molecular compounds by disrupting the
intermolecular attractive forces. Some compounds are insoluble in water because the forces holding the solute
particles together are too strong to be overcome. - Ionic compounds are electrolytes because they dissociate into ions when dissolved in water. Many molecular
compounds are nonelectrolytes. Polar molecular compounds may be either strong or weak electrolytes,
depending on the extent of their ionization in aqueous solution.
Lesson Review Questions
Reviewing Concepts
- Identify the solvent and the solute for a solution of sugar in water.
- Why is water a good solvent for most ionic and polar covalent compounds but not for nonpolar compounds?
- What is the difference between solvation and hydration?
- What type of particles must be present in a solution for it to conduct electricity?
- When iron(III) nitrate dissolves in water, what ion is attracted to the oxygen atom of the water molecule?
What ion is attracted to the hydrogen atoms? - How is a weak electrolyte different from a strong electrolyte? What types of compounds can be weak
electrolytes? - What types of liquids are miscible with water? What types are immiscible?
Problems
- Which of the following would dissolve in water and which would not? Explain each choice.
a. CH 4
b. HBr
c. AgCl
d. K 2 SO 4
e. I 2
f. NH 4 Cl- Write dissociation equations for the following strong electrolytes.
a. CoCl 3
b. NH 4 Br
c. Al(NO 3 ) 3
d. Na 2 CO 3
e. ZnSO 4
f. Li 2 S- Hydrogen fluoride gas is a polar covalent molecular compound that dissolves in water to form a weak elec-
trolyte. Write the equation for this process. - Methanol (CH 3 OH) is a nonelectrolyte, but it is miscible with water. Write an equation for the dissolution of
methanol in water.