solubility
A supersaturated solution is a solution that contains more dissolved substance than a saturated solution does. This occurs when a solution is prepared at a higher temperature and is then slowly cooled. This is a very unstable situation, so any disturbance causes precipitation.
Solubility can be understood in terms of two factors:
The natural tendency toward disorder favors dissolving.
The relative forces between and within species must be considered.
Stronger forces within solute species oppose dissolving.
Stronger forces between species favor dissolving.
For molecular solutions, this can be summarized as “Like dissolves like.” In other words, solutes dissolve in solvents that have the same type of intermolecular forces.
An immiscible solute and solvent are illustrated at right.
Helium–oxygen mixtures are sometimes used as the breathing gas in deep-sea diving. At sea level (where the pressure is 1.0 atm), the solubility of pure helium in blood is 0.94 g/mL. What is the solubility of pure helium at a depth of 1500 feet?
Pressure increases by 1.0 atm for every 33 feet of depth, so at 1500 feet the pressure is 46 atm. (For a helium–oxygen mixture, the solubility of helium will depend on its initial partial pressure, which will be less than 1.0 atm.)
An experiment calls for 36.0 g of a 5.00% aqueous solution of potassium bromide. Describe how you would make up such a solution.
A 5.00% aqueous solution of KBr has 5.00 g KBr per 100. g solution. The remainder of the 100. g is water: 95 g.
We can use this ratio to determine the mass of KBr in 36.0 g solution:
Since 1.8 g KBr is required for 36.0 g of solution, the remainder consists of 34.2 g water.
We make the solution by mixing
1.8 g KBr in 34.2 g water.
Molality is the moles of solute per kilogram of solvent. It is abbreviated as m.
Iodine dissolves in a variety of organic solvents. For example, in methylene chloride, it forms an orange solution. What is the molality
Solubility can be understood in terms of two factors:
The natural tendency toward disorder favors dissolving.
The relative forces between and within species must be considered.
Stronger forces within solute species oppose dissolving.
Stronger forces between species favor dissolving.
For molecular solutions, this can be summarized as “Like dissolves like.” In other words, solutes dissolve in solvents that have the same type of intermolecular forces.
An immiscible solute and solvent are illustrated at right.
Helium–oxygen mixtures are sometimes used as the breathing gas in deep-sea diving. At sea level (where the pressure is 1.0 atm), the solubility of pure helium in blood is 0.94 g/mL. What is the solubility of pure helium at a depth of 1500 feet?
Pressure increases by 1.0 atm for every 33 feet of depth, so at 1500 feet the pressure is 46 atm. (For a helium–oxygen mixture, the solubility of helium will depend on its initial partial pressure, which will be less than 1.0 atm.)
An experiment calls for 36.0 g of a 5.00% aqueous solution of potassium bromide. Describe how you would make up such a solution.
A 5.00% aqueous solution of KBr has 5.00 g KBr per 100. g solution. The remainder of the 100. g is water: 95 g.
We can use this ratio to determine the mass of KBr in 36.0 g solution:
Since 1.8 g KBr is required for 36.0 g of solution, the remainder consists of 34.2 g water.
We make the solution by mixing
1.8 g KBr in 34.2 g water.
Molality is the moles of solute per kilogram of solvent. It is abbreviated as m.
Iodine dissolves in a variety of organic solvents. For example, in methylene chloride, it forms an orange solution. What is the molality