20 Questions
According to the text, what is the most important factor in determining the solubility of a substance?
The relationship between the substance and the solvent in terms of structure
What must be supplied in dissolution, melting, and boiling processes?
Heat
Which type of solvents are able to dissolve ionic compounds appreciably?
Highly polar solvents
What type of molecule has a positive end and a negative end?
Polar molecule
What is the main source of energy required to break the bonds between solute particles?
Formation of bonds between solute particles and the solvent molecules
What is the result of the reaction between a carboxylic acid and NaHCO3?
Formation of a water-soluble salt and evolution of CO2
What type of compounds are usually soluble in concentrated H2SO4?
Compounds containing carbon-carbon pi bonds, oxygen, nitrogen, or sulfur
What causes the formation of a dark solution or precipitate when a compound reacts with concentrated H2SO4?
Presence of certain functional groups reacting with the concentrated acid
What is the significance of the presence of an amino group in a compound when it reacts with dilute acids?
Forms water-soluble ammonium salts
What is the outcome when a phenol containing strong electron-withdrawing substituents reacts with NaHCO3?
Forms a water-soluble sodium salt
Which factor decreases the polarity of a compound?
Adding carbon atoms to the chain
What can increase the solubility of a compound in water?
Hydrogen bonding between solute and solvent
Which type of organic compounds are usually highly soluble in water?
Carboxylic acids and phenols
How do organic compounds become ions in order to be water-soluble?
Primarily through acid-base reactions
What happens when low-molar-mass organic compounds containing polar groups form hydrogen bonds with water?
They are generally soluble in water
Which type of compounds dissolve in solvents based on their polarity?
Non-ionic compounds in polar solvents
What term is used to describe the ability of a substance to dissolve in a solvent?
Solubility
In what type of solvents do ionic compounds dissolve due to ion-dipole bonds?
Solvents with high dielectric constant
What is the measure of solubility described in terms of grams of solute per liter or milligrams of solute per milliliter?
Concentration
What do two liquids that are miscible do when mixed together?
Mix homogeneously in all proportions
Study Notes
- Ionic compounds dissolve in solvents with high dielectric constant, such as water, due to ion-dipole bonds formed between ions and solvent molecules.
- Solvent molecules surround ions in solution and form a cluster around them, called solvation or hydration.
- Water's superiority as a solvent for ionic substances comes from its polarity, high dielectric constant, and ability to form hydrogen bonds.
- Solubility is the ability of a substance to dissolve in a solvent.
- Non-ionic compounds dissolve in solvents based on their polarity: polar compounds in polar solvents, and nonpolar compounds in nonpolar solvents.
- Solubility can be described in terms of grams of solute per liter (g/L) or milligrams of solute per milliliter (mg/mL).
- Three techniques in organic chemistry laboratory, crystallization, extraction, and chromatography, are based on the solubility of substances.
- Two liquids that are miscible mix homogeneously in all proportions, while immiscible liquids do not mix homogeneously in all proportions and form two layers.
- Solubility and miscibility are related concepts, but solubility has degrees, while miscibility does not.
- To predict the solubility and polarity of molecular solutions, follow the guidelines: 1) hydrocarbons are nonpolar, 2) compounds with oxygen or nitrogen are polar, 3) halogen atoms do not significantly alter the polarity of an organic compound.
Test your knowledge of predicting polarity and solubility of organic compounds with this quiz. See if you can identify how the addition of carbon atoms to a chain affects the polarity and solubility of compounds.
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