unit 13 solutions :/ Flashcards by Mino Furtado

solution

homogenous mixture of two or more substances: clear and will NOT disperse light

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solvent

dissolves solute

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solute

dissolved by solvent

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soluble

able to be dissolved

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miscible vs immiscible

two LIQUIDS that can mix are miscible, if two liquids cannot they are immiscible (oil and water)

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solvation

the process of dissolving a solute

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how can you tell which is solute and which is solvent?

solvent is usually the bigger component, solute is smaller

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the solubility rule

‘like dissolves like’
substances are soluble when IMFs and forces of attraction are similar

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“like dissolves like” rule

polar dissolves polar AND ionic
nonpolar only dissolves nonpolar

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why does like dissolves like work

full charges attract full charges partial charges attract partial charges
nonpolar charges attract IMFs
polar molecules prefer more polar things to fully satisfy charges

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review LDMs and polarity

LDM ionic
1. draw kernel (symbol with oxidation # changed)
2. put brackets
3. put ion charges around brackets

Molecule LDM
1. add valence electrons
2. put LEAST electroneg in the middle except not hydrogen or halogens
3. -2 es for every bond connecting and put two dots around every atom until 8 around every atom
4. form multiple bonds if necessary

remember, H2S is polar goddamn it

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electrolyte

a chemical compound that ionizes when dissolved OR MOLTEN and forms an electrically conductive substance
ionic compounds are electrolytes bc they dissolve/melts into loose ions with charges

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non electrolytes

no mobile ions produced, just molecules (e.g. sugar)
most compounds starting with ‘C’ are nonelectrolytes (unless acid or base sometimes) and bad conductors are not usually electrolytes. covalent = non electrolyte

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strong vs weak electrolytes

strong electrolytes ionize completely and have a strong current
weak electrolytes ionize partially and have a weaker current

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is solution formation a physical or chemical change?

physical change (you can get back solute by evaporating solvent)

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temperature effect on solubility (and why) (for liquids and solids)

increase in temp increases solubility
because particles move faster and move more particles around

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temperature effect on solubility (and why) (for gases)

temp increase causes solubility decrease for gases because thermal and kinetic energy overcome attractive forces (LDFs)

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pressure effect on solids

no pressure effect on solubility of solids

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pressure effect on gases

direct relationship: as pressure increases solubility increases

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particle size and solubility

smaller particle size increase solubility because can dissolve all at once all exposed

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agitation

increase solubility bc mixing

solution equilibrium

another name for a saturated solution: rate of dissolving is equal to the rate of deposition

concentration

measurement of the amount of solute in a volume of solvent

concentrated solution

one mole or more of solute

diluted solution

less than one mole of solute

molarity

how we express concentration

molarity equation: M

moles of solution/liters of solution

how to make the solution the desired molarity

1. amount of solute needed weighed out on a balance 2. portion of the solvent is added to the volumetric flask 3. mixture swirled until solute is dissolved 4. more solvent added until it reaches the mark on the flask

dilution

adding water to an existing solution

stock solution

concentrated solution needed to be diluted

working solution

solution we end up with after diluting

can you add acid to water or water into acid?

NEVER add water into acid ALWAYS acid into water

what is #M vs m vs 'm' in italics

M is molar, m is moles, and m in italics is molality

ppm formula

mass of solute/mass of solution x 10^6

percent composition

mass of part/mass of whole x 100

percent volume

volume of solute/volume of solution x 100

molality

concentration unit, but NOT temp dependent like molarity (bc liters is volume and volume is temp dependent)

molality equation

moles solute/kg solution

mole fraction calcs

nx = moles part/moles total

dissociation equation

shows the ions that an ionic compound will dissolve into -always H2O on arrow because dissolved in water -take number on bottom and separate each element and put it in front and then total numbers up (assuming compound is ionic)

van't hoff number

an integer that equals the TOTAL number of particles into which the solute dissociates when it is dissolved in solution -answer to the dissociation equation -represented by i

ion concentration/total molar concentration of molar compound

takes M and do dissociation equation but with moles in answer, just multiply all numbers by the number in front of M

colligative properties

physical properties that WILL CHANGE when solute is present -change is based on how many particles are added

boiling point colligative property

boiling point increases because dissolved particles will interfere with boiling process

freezing point colligative property

freezing point is lowered with solute because solute particles will interfere with lattice formation

vapor pressure colligative property

solute lowers vapor pressure because the it obstructs the exit pathway for molecules

colligative calculations

seek to calculate new boiling and freezing point after solute added

colligative calculations formulas

DT = Kb m i DT = Kf m i DT = change in temp Kb = molal constant boiling: 0.52 deg C/m Kf = molal constant freezing: 1.86 deg C/m m (italics) = molality i = van't hoff number

Kb (molal constant boiling)

0.52 degrees C / molal

Kf (molal constant freezing)

1.86 degrees C / molal

temperature effect on solubility and why (for gases)