solutions and their behavior ch 8 Flashcards
what is a Solution
A solution is a homogeneous mixture that consists of one or more solutes uniformly dispersed at the molecular or ionic level throughout a medium known as the solvent.
Air is a solution of nitrogen, oxygen, and a few other minor gases.
what is a Solvent
Solvent is present in the larger amount.
Solute what is it
Solute is present in smaller amount than the solvent.
example of a solvent and solute
Normal saline is a solution containing sodium chloride and water. The sodium chloride comprises 0.89% of the mixture and water comprises 99.11% of the mixture, NaCl is the solute and water is the solvent.
Molality (m) what is it
, or molal concentration expresses concentration in terms of moles of solute per kilogram of solvent.
m= moles solute/ kg solvent
Molarity, what is it
or molar concentration is defined as moles of solute per liter of solution.
Molality is never equal to molarity.
The difference becomes smaller as solutions become more dilute.
M= moles solute/ L solution
percent means part per what
100
unit of concentration formula or percent by weight to volume
% = g of solute/ 1000 ml of solution
Example: Drug is packaged 5mg/5ml. You want to give 10mg. How many ml will you give?= 10 ml
the percent by weight formula =
% (w/w)= 25 g of glucose/ 500g of solution x 100 = 5%
Solubility is what
Solubility is the amount of solute that will dissolve in a given amount of solvent
Saturated is what
A saturated solution contains the maximum amount of a solute, as defined by its solubility.
Supersaturated means
This is not a stable system
A solution contains more solute than allowed by the solubility.
can turn vaporizer to high concentration for a short period to drive in more gas.
Supersaturated example
The excess solute will come out of solution crystallizing as a solid, separating as a liquid, or bubbling out as a gas.
For example, when blood or urine in the kidneys becomes supersaturated with calcium oxalate or calcium phosphate, a kidney stone can form.
If the solute is a gas in liquid solvent, you would see bubbles forming in the solution. Perhaps you’ve seen this phenomenon when you open a bottle of beer or soda pop.
Two liquids are blank if they are soluble in each other in all proportions.
Miscible
Miscible
example
Two liquids are miscible if they are soluble in each other in all proportions. Alcohol and water are miscible with each other. Oil and water, on the other hand, are immiscible with each other.
Solubility Guidelines
Like dissolves like
Polar solutes are more soluble in polar solvents
Nonpolar solutes are more soluble in nonpolar solvents
you dont want your gases to be absorbing into the blood because it would take a long time for pt to wake up. our gases are quick active now.
The solubility of a solute is the amount of what
the solute that will dissolve in a given amount of solvent at a given temperature.
Solubility Guidelines example
That means that polar solutes are more soluble in polar solvents, while nonpolar solutes are more soluble in nonpolar solvents. You can consider most organic compounds to be nonpolar.
The most polar species are, obviously, ionic compounds, followed by species that can form hydrogen bonds, such as water and ethanol (CH3CH2OH). Therefore, you would expect ionic compounds to be soluble in water, but not very soluble in an organic solvent such as ether or hexane.
!!!!On the other hand, you would expect an organic compound, like the vast majority of the pure form of injectable medications, to be relatively insoluble in a water-based medium such as blood.!!!!!
Solubility Example: Lidocaine
Lidocaine is not very soluble in water. Lidocaine belongs to the class of organic compounds called amines, and amine functional groups contain a nitrogen atom.
Lidocaine (a nonpolar, water-insoluble organic compound) reacts with hydrochloric acid to give an ionic salt, which is called lidocaine hydrochloride (the drug). Because lidocaine hydrochloride has an ionic bond, it is readily soluble in water.
can change the compounds of drugs to make them more useful.
Energy Changes of Solution Process
Energy flows into the system during an endothermic process, whereas energy flows out of the system during an exothermic process.
Some substances have positive (endothermic)
transfer of heat goes from hot to cold.
Heat is the transfer of energy into or out of a system caused by a difference in temperature. T/F
true
Solvation process:
Chemical bonds require lattice energy to bind together. The energy (heat) required to break or solvate those bonds is the solvation process.
Solvation process example
Whether or not the heat of solution is an endothermic or an exothermic process depends on the relative magnitudes of the lattice energy and the heat of solvation. If tearing the ions apart requires more energy than is released by solvation, then ΔHsolnis going to be positive (endothermic). If the energy released by solvation is greater than the energy required to tear the ions apart, ΔHsolnis going to be ex
Effect of Pressure on Solubility
Gaseous solute As P increases, solubility increases Henry’s Law Sgas = kHPgas S = solubility, k = constant, P = partial pressure
Liquid and solid solutes
P has negligible effect
Pressure has a dramatic effect on the solubility of gaseous solutes in liquid solvents
As pressure increases, the solubility of a gaseous solute in a liquid solvent increases.
Effect of Pressure on Solubility example
Carbonated beverage: Have you noticed that when you open a bottle of champagne (or soda pop, or beer, or club soda), small bubbles of carbon dioxide gas start to form? That “pop” you hear when removing the cork is caused by the escape of excess carbon dioxide gas from the bottle.
When the gas escapes, the pressure in the container decreases. With less pressure, the solubility of the carbon dioxide dissolved in the champagne decreases.
Since solids and liquids are not very compressible, at least not compared to gases, pressure has what affect
has very little effect on the solubility of solid and liquid solutes.
Henrys Law
The amount of a non reacting gas which dissolves in liquid is directly proportional to the partial pressure of the gas, provided the temperature remains constant.
henry law example
If we increase the partial pressure of a gas, that means there are more of those gaseous molecules (in a given volume, at a given temperature) zipping around near the surface of the liquid. Doesn’t it make sense that more of the gas molecules will be trapped by the liquid solution? Also, if the dissolved gas molecules were to escape into the gas phase, the pressure would increase. So, assuming that the pressure remains constant, the would-be escapees are crushed back into solution.
Effect of Temperature on Solubility
Gaseous solute
As T increases, solubility decreases
Think about opening a warm can of soda pop …the carbon dioxide is less soluble and comes bubbling out.
Liquid and solid solutes As Temperature increases,
solubility generally increases.
example important !!!! henry law
Important Concept: Temperature effects solubility, therefore a patient who is cold receiving an anesthetic gas, solubility INCREASES, and their emergence (wakeup) will be longer. Important on many levels to keep patients normothermic in the OR
Temperature Effect
The amount of gas dissolved is inversely proportional to the temperature. (the colder the liquid (blood), the more gas that will dissolve in the liquid).
Cold patients take longer to wake up if using an inhalational agent.
As solutes are added to a solution what happens
the physical properties of the solution change.
Colligative Properties of Solutions
A colligative property depends only on the number of solute particles, not the identity of the solute particles
Colligative properties include
Colligative properties include:
- The vapor pressure of a solution decreases with increasing solute concentration.
- The boiling point of a solution increases with increasing solute concentration.
- The freezing point of a solution decreases with increasing solute concentration.
- The osmotic pressure of a solution increases with increasing solute concentration.
Vapor Pressure
Vapor pressure of liquid results from the most energetic molecules near the surface of the liquid escaping into the gas phase.
amount of molecules that escape after heating something.
Raoult’s Law
The vapor pressure of a solution
Raoult’s law states the vapor pressure of a volatile component of a solution (P) is equal to the vapor pressure of the pure substance (P°) times the mole fraction (χ) of that substance.
Boiling Point Elevation
The temperature at which the vapor pressure of the material is equal to the ambient pressure.
ex. Adding salt to the water to cook pasta, slightly increases the boiling point.
Boiling Point Elevation info
the vapor pressure of a solution is decreased by the addition of nonvolatile solutes, a higher temperature is needed to drive the vapor pressure up to the point where it equals the ambient pressure.
the boiling point of a solution increasesas the concentration of solute(s) increases. The change in boiling point is directly proportional to the molal concentration of the solute particles.
Freezing Point Depression
the temperature at which the liquid phase of the material is in equilibrium with the solid phase.
necessary to cool the sample to lower temperatures, thereby lowering the kinetic energy of the molecules even further, before they will settle into the solid phase.
Osmotic Pressure
The one with the greater concentration is the hypertonic solution, and the one with the lower concentration is the hypotonic solution.
The relative concentration of solutes in osmotic systems is called the
tonicity.
Isotonic
if they contain equal concentrations of particles.
Osmosis is
the diffusion of water, and diffusion always spontaneously occurs in the direction from an area of high concentration to an area of low concentration.
osmosis example
Since the concentration of water in the hypotonic solution is greater than the concentration of water in the hypertonic solution, osmosis always spontaneously occurs from the hypotonic solution to the hypertonic solution.
Entropy
demands that osmosis occur between two solutions of unequal tonicity until the concentrations of the two solutions are equal.
are colloids true solutions?
Colloids are not true solutions,
The pulling power of proteins!
colloid particle size?
Particle size is on the order of 200 nm
Might be super-sized molecules (e.g., proteins) or aggregates of ions
Colloidal particles cannot be filtered and do not settle out of solution.
Examples:
Blood, milk, jelly. Albumin