Chapter 17 Solutions Flashcards by Louis Mendoza

Dalton’s Law of partial pressures

The P total is the sum of all partial pressures
Ptot= Pgas1 + Pgas 2 + Pgas3…

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A solution has two components.

A solute (lesser) A solvent (greater)

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Solutions Examples (Solute and Solvent)

Humidity - Gas - Gas
Rain - Liquid - Gas
snow - Solid - Gas
Carbonated Drinks, Sodas - gas -Liquid
Gin and Tonic - Liquid - Liquid
Salt Water, Solutions in lab- Solid -Liquid

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Solution concentration

Molar (M)= amount of solute (moles)/ volume of solution (liters)

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Percents (Formulas)

Mass percent:
(mass of solute/mass of solution) x 100
Volume percent:
(volume of solute/volume of solution) x 100) Volume is based on the initial volumes.
Mass Volume percent
(mass of solute(grams)/ volume of solution(mL)) x 100

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Parts per Unit

a. Part per million:

1ppm= 1mg/L = 1g solute/ 1 x10^6g solution

b. Part per billion

1ppb = 1 ug/L = 1g /10^9 solution

c. Part per trillion

1ppt = 1ng/L = 1g/ 10^12 g solution

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Mole Fraction (xi) and Percent
Mole percent xi (100)

xi = moles of i/ (total solution moles)

where xi +xj + xk+… =1.00

mole percent = 100xi

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Molality(m)

amount of solute (moles)/ mass of solvent (kg)
Molality and Molarity are equal for dilute solutions where water is the solvent
Solution density is that of water (1g/mL)
(1L solution) (1000mL/L) (1g/mL) (kg/1000g) = 1kg solution

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Normality (N)

the molarity multiplied by the number of equivalents. Used with acids( H+), bases (OH-), redox and precipitation
Normality (N) = ( # of equivalents) (Molarity)

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Solubility

amount of solute that can be dissolved in a solvent.

Solubility = grams of solute dissolved/ given mass or volume of solvent

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Molar Solubility

units are moles of solute per liter of solution
M soln = M solute + M solvent

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Volume formula

Sometimes they are additive unless there is stated volume change or density change
V soln = V solute + V solvent

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Polar molecules

Asymmetric molecules
Water, ionic compounds, salts, Alcohol, Water-Soluble Compounds, Hydrophillic

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Non-polar molecules

Symmetric molecules
- Hydrocarbons
Molecular compounds
Oils, etc.

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Like dissolves like idea

When polar molecules interact with other polar molecules, and non-polar molecules interact with other non-polar molecules they dissolve each other.

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Enthalpy of solution

Enthalpy solution > 0 is endothermic
Enthalpy of solution < 0 is exothermic

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Factors that contribute to enthalpy of solution

Breaking the solute into individual components, called expanding the solute endothermic
- Overcoming intermolecular forces in solvent to make room for the solute called expanding the solvent. (H2) endothermic

Allowing the solute and the solvent to interact to form a solution (H3) exothermic

H soln = H1 + H2 + H3

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Ideal solution

Change in enthalpy = 0

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Possible combinations:

Solutes and Solvents:
Polar = Enthalpy large > 0
Non-polar with Enthalpy is small. < 0

When all values are small or Large they cancel each other out or dissolve and become small.

A mixture of both small and large: Total enthalpy = Large

Total Enthalpy small = solution forms
Total Enthalpy Large = no solution forms

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Solution formation and equilibrium

Dissolving process will occur until equilibrium is reached
Solute + Solvent = Solution

Solubility (increases with temp except sulfates and phosphates).

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Saturated

Saturated line represents the point where the dissolution and crystallization are both occuring and in equilibirum wiht each other

Undersaturated

Region on the graph below the saturated line when the solven cen dissolve more solute than available.

Supersaturated

Region on the graph occurs when the solution has more solute in solution than equlibrium allows.
Scenario = unstable and cause excess solute to crystalize

Fractional Crystallization

Solubulity to seperate solute.
Ex: Impure solid with mostly A and some B. Dissolve solide in high
temp then cool solution and each A and B will crystalize at different times.

Structure effects

Structure is affected extremely by solubility: Fat soluble compound are non-polar Water-soluble compounds are polar

What are Fat soluble compounds composed of?

Mostly C and H atoms and possibly on e OH group

What are water-soluble compund composed of

Mostly OH groups (polar) along with C and H atoms

Temp effects

- Soldis dissolved in liquids = solubility increases as temp increaese - gases dissolved in liquids = the solubility of a gas in a liquid decrease as temperature increases. Reason is because the increase temp increases the kinetic energy of the gas causing the gas to escape the solution

Pressure effects (For gases dissolved in liquid

As pressure increases the solubility of a gas in a liquid increase

Henry's Law

C is solubility or concentration. K is Henry's law constant. Pgas = pressure of gas Formula examples C= k Pgas k = C1/P1 = C2/P2 C= mol/L

Raoult's Law

Partial pressure (Pa) = to the mole fraction (xa) multiplied by the pure pressure of solvent (PA o) Pa = xa PoA Pb = xbPbO Xa +Xb =1.00 Ptot = Pa+ PB Ptot = xA PA^o + xbPB^o PA = xAPtot

novolatile

Does not have an appreciable vapor pressure. Partial pressure of the solvent is the only contributor to total pressure.

Negative deviation

When there is a mixture of polar molecules

Positive deviation

When there is a mixture of polar and nonpolar molecules

Behavior of various types of solutions

Unlike forces = like forces (Enthalpy soln) = 0 Raoul's law Deviation: None(ideal solution) Polarity: Nonpolar -Nonpolar interaction Unlike forces > like forces Enthalpy soln (Negative ) Raoult's Law deviation: Negative Polarity Polar- Polar interaction Unlike forces < like forces Enthalpy solution (Positive) Raoult's Law Deviation Positive Polarity Nonpolar - polar interaction

Osmotic Pressure (Π)

When a solute is separated by a semipermeable membrane, pure solvent will pass into the solution by osmosis= large pressure Π = MRT M= Molarity T in Kelvin. R is 0.08206 L atm/mol K.

Chang in temperature is calculated as follows where k is given constant for the solvent and m is molarity.

Change in T = km Concentration should be considered when there is a change in temperature. Also, when you calculate the boiling point of a value and you are solving for change in enthalpy add an additional 100 celcius

Bp and Fp relasonship

If it takes more energy for the solvent molecules to leave the solution the bp will be higher Concentration should be considered

Colligative properties affect fp, bp, and Π

Also, they use an electrolyte as a solute is adjusted by the van't Hoff factor. Eelctrolyes need adjustment because they sperate in solution adding more particles than expected. i = moles of particles in solution/ Moles of solute dissolved i has different values depending on the compound. If compound is weak on non-electrolyte then i =1.

Strong electrolytes

Strong acids Strong Bases Ionic compounds Salts

Weak or Non-Electrolytes

Weak acids (any state) Weak bases (any state) Molecular Compounds Organic compounds Liquids, Solids, and gases.

Colligative property formula include i as follows

Change in T = ikm Π = iMRT

Colloid

A suspension of particles which is stabalized by electrostatic repulsion.

Mass percent formula

Mass of solute in grams/ total mass (in grams) x 100 percent

Volume percent

Volume of solute (in mL) / total volume (in mL) x 100 percent

Mass Volute Percent Formula

Mass of solute in grams / total volume (in mL) x 100 percent

Low solute concentrations of aqueous solutions are express using ppm

Mass of solute (in grams)/ total mass (in grams) x 10^6

Mole fraction

Xi = moles of component i/ total moles of all components X1 + X2 + X3 + … Xn = 1

Mole % i

Xi x 100percent

Molarity (M)

Moles of solute/ volume of solution (in liters)