Ch. 8 Solutions Flashcards by Sinead Zoellner

Composed of 2 or more pure substances.

May be Heterogeneous or Homogeneous.

Mixtures

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A mixture that does not have a uniform composition throughout a sample.

Heterogeneous

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A mixture that has a uniform composition throughout a sample.

Homogeneous

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A homogeneous mixture that contains small particles.

Liquid solutions are transparent. Can not be separated by filtration.

Solutions

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When 2 substances form a solution, the substance present in the lesser amount is called the ____

solute

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When 2 substances form a solution, the substance present in the larger amount is the _____

solvent

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A solution with water as the solvent is called an ____

aqueous solution

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Mixtures that contain larger particles than particles in a solution.

Colloids and Suspensions

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A homogeneous mixture with larger particles (1nm-1~m in diameter) often having an opaque appearance. Can not be separated by common filtration techniques.

Colloid

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A heterogeneous mixture that contains large particles (greater than 1~m in diameter) suspended in a liquid. Can be separated by filtration or centrifugation.

Suspension

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A substance that conducts electric current in water.

Electrolyte

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A substance that does not conduct an electric current in water.
Examples: CH3CH2OH, H2O2

Nonelectrolyte.

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Electrolytes can be classified as strong or weak depending on the extent that the compound _____ or forms ions.

Dissociates

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Dissociates completely to form ions when dissolved in water.

Example: NaCl because Na+ cation and Cl- anion
Other examples: KOH, HCl, KBr

Strong electrolytes

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Dissolves in water to yield largely uncharged molecules-a small fraction of the molecules form ions.

Example: Ammonia (NH3) dissolves in water and the predominant species in then NH3.
Other examples: HF, CH3CO2OH

Weak electrolytes

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A unit used to express the amount of each ion in a solution.

Equivalents (Eq)

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The # of moles of charge that a mole of ions contributes to a solution.
Give an example.

Equivalents such as 1 mole of K+= 1 Eq of K+ ions b/c potassium bears a +1 charge.

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How many Eq of sulfate (SO4^2-) are present in a solution that contains 3.2 moles of SO4^2-?

6.4 Eq SO4^2-

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The amount of solute that dissolves in a given solvent. Reported in grams of solute per 100mL of solution (g/mL)

Solubility

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A solution that has less than the maximum number of grams of solute

unsaturated

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A solution that has the maximum number of grams of solute that can dissolve.

saturated

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Solubility is often described in these three words…

“like dissolves like”

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Most ionic and polar covalent compounds are soluble in water.

A polar solvent

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Non-polar compounds are soluble in ____.

Non-polar solvent

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Water soluble compounds are ionic or are small polar molecules that can hydrogen bond with the ____

water solvent

An attraction of an ion with a dipole in a molecule

Ion-dipole interaction

The process of surrounding particles of a solute with solvent molecules.

Solvation

____ _____ for uncharged molecules occur only with small polar molecules or those with many O or N atoms that can hydrogen bond to water.

Water Solubility

When the solvation releases more energy than that required to separate particles, the overall process is_____ (heat released)

Exothermic

When the separation of particles requires more energy than is released during solvation, the process is_____ (heat absorbed)

Endothermic

Rule 1 of solubility of ionic compounds is: a compound is soluble if it contains one of the following cations:

Group 1A cations: Na+, Li+, Rb+, Cs+, K+ | Ammonium NH4+

Rule 2 of solubility of ionic compounds is: a compound is soluble if it contains one of the following anions:

Halide- Cl-, Br-, I-, except for salts w/ Ag+, Hg^2+, Pb^2+ Nitrate- NO3- Acetate- CH3CO2 Sulfate- SO4^2-, except for salts w/ Ba^2+, Hg^2+, Pb^2+

As temperature increases the solubility generally increases and is true for most ionic and molecular solids. The solubility of gases typically decreases with increasing temperatures. This describes what.

Temperature effects on solubility

The solution contains more than the predicted max amount of solute at a given temperature.

Supersaturated

This does not affect the solubility of liquids and solids but does affect the solubility of gases.

Pressure effects on solubility

The solubility of a gas in a liquid is proportional to the partial pressure of the gas above the liquid. The higher the pressure, the higher the solubility of a gas in a solvent.

Henry's Law

How much solute is dissolved in a given amount of solution.

Concentration

The most common measure for a concentration is?

weight/volume percent (w/v %)

Mass of solute (g) _____________ x100% Volume of solution (mL)

w/v % equation

The number of mililiters of solute dissolved in 100mL of solution

Volume/Volume percent (v/v %)

Volume of solute (mL) ____________________ x100% Volume of solution (mL)

v/v % equation

Using the percent concentration as a conversion factor

It's used to relate the amount of solute to the amount of solution

When a solution contains a very small concentration of solute, the concentration is often expressed in ___ ____ _____

Parts per million (ppm)

The number of "parts" in 1,000,000 parts of solution

parts per million

"parts" may be expressed in mass or volume as long as the same unit is used for both _____ and _____.

numerator and denominator

Mass of Solute (g) _______________ x10^6 Mass of Solution (g)

ppm equation

Volume of Solute (mL) __________________x 10^6 Volume of Solution (mL)

ppm equation

The number of moles of solute per liter of solution and is abbreviated as M.

Molarity

Moles of solute (mol) _________________ Liters of solution (L) mol/L

Molarity equation

The addition of a solvent to decrease the concentration of the solution.

Dilution

In dilution, only the solute is constant, the _____ of the solution is changed by adding the solvent.

Volume

Moles of solute= Molarity x Volume M1xV1=M2xV2

Dilution formula

Properties of a solution that depend on the concentration of the solute but do not depend on its identity.

Colligative Properties

A lower vapor pressure means that the solution must be heated to a higher temperature to get the vapor pressure to equal the atmospheric pressure.

Boiling Point Elevation

A solute in a solution that readily escapes into the vapor phase is said to be ______

Volatile

A solute in a solution that does not readily escape into the vapor phase and has a negligible vapor pressure at a given temperature is said to be ______.

Non volatile

A liquid that contains a ________ solute has a higher boiling point than the solvent alone.

Non volatile

One mole of any non volatile solution raises the BOILING point of one kilogram of water by ______.

.51 degree C.

The presence of solute molecules makes it harder for solvents molecules to form an organized crystalline solid, this lowering the temperature at which the liquid phase becomes a solid.

Freezing Point Depression

A liquid solution that contains a ________ solute has a lower freezing point that the solvent alone.

Non volatile

The amount of freezing point depression depends ONLY on the____

Number of dissolved particles.

One mole of any non volatile solution lowers the FREEZING point of 1 kilogram of water by _______.

1.86 degrees C.

A membrane that allows small molecules to pass across, but ions and large molecules cannot.

Semipermeable membrane

The passage of solvent, usually water, across a semipermeable membrane from a solution of low solute concentration to an area of higher solute concentration.

Osmosis

The pressure that prevents the flow of additional solvent into a solution on one side of a semipermeable membrane.

Osmotic Pressure

The greater number of _____ the greater the osmotic pressure.

dissolved particles.

.1 M glucose solution is separated from .2 M glucose solution by a semipermeable membrane. Which solution exerts a greater osmotic pressure? Why?

The greater the dissolved particles, the higher the osmotic pressure. .2M has higher dissolved particles therefore it exerts the greater osmotic pressure.

.1 M glucose solution is separated from .2 M glucose solution by a semipermeable membrane. Which way will water flow?

Water will flow from less solute concentration .1 M to higher solute concentration .2 M.

.1 M glucose solution is separated from .2 M glucose solution by a semipermeable membrane. What is the level of 2 solutions once equilibrium is reached?

Since water flows into .2M solution, the height will increase on this side and decrease on the .1 M side.

Two solutions with the same osmotic pressure are said to be____

Isotonic.

Movement of water into and out of red blood cells occurs to an equal extent.

Isotonic solution

More water moves into cell than diffuses out- the cell swells and can rupture. This has lowe osmotic pressure than body fluids.

Hypotonic solution

More water moves out of the cell than diffuses in-the cell shrivels. This solution has a higher osmotic pressure than body fluids.

Hypertonic solution

This process involves selective passage of substances across a semipermeable membrane called a dializing membrane.

Dialysis