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Explain what is meant by the expression “like dissolves like.”
Substances with “like” polarity will dissolve in each other.
An unknown compound is observed to mix with benzene (a nonpolar solvent) but not with water. Is the unknown compound ionic or covalent?
If the unknown compound (from the previous question) is a liquid, will it be able to dissolve table salt?
No, table salt is an ionic compound. Since the unknown compound is covalently bonded, it will not dissolve an ionic compound. “Like dissolves like.”
What are the chemical characteristics of a good dry-cleaning solvent?
Because “like dissolves like”, a good dry-cleaning solvent should be nonpolar (covalent) so that it can dissolve oil and grease.
Some industrial plants use water from nearby rivers and streams as a coolant. When the water is returned to the river or stream, the water is warmer than it was originally. This is referred to as “thermal pollution”. Using your knowledge of solubility, why might this thermal pollution be harmful to fish?
The warmer the water, the less oxygen can be dissolved. The decrease in dissolved oxygen could cause a fish kill.
After a bottle of carbonated drink has been open for a while, it tastes “flat”. Explain why.
According to Henry’s Law, more carbon dioxide can be dissolved under pressure. When the bottle of carbonated drink is opened, the pressure is decreased and the excess carbon dioxide escapes, causing the soda to taste flat.
Describe what happens to the degree of solubility of a gaseous solute in a liquid:
a) with a decrease in the temperature of the solvent.
b) with an increase in pressure (Henry’s Law).
Solubility of a gaseous solute in a liquid solvent increases with a decrease in temperature.
Solubility of a gaseous solute in a liquid solvent increases with an increase in pressure.
The following statement is FALSE: It is not possible to make a saturated solution from a substance that is described as only slightly soluble. Explain why this statement is false.
It is possible to make a saturated solution from a substance that is described as only slightly soluble. It just isn’t possible to make a concentrated solution from a substance that is described as only slightly soluble.