Solubility and Equilibrium Flashcards

1
Q

Electrolyte strength reflects…

A
  • the NUMBER OF IONS that can be formed from an electrolyte in an aqueous solution.
  • strong electrolytes fully ionize
  • a solution that conducts electricity
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2
Q

General examples of weak electrolytes

A
  • weak acids/bases that are not fully ionized/dissociated

- salts that are weakly soluble

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3
Q

To know for the solubility guidelines: what are acetates, bicarbonates, perchlorates

A

acetates C2H3O2-
bicarbonates HCO3-
perchlorates CLO4-

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4
Q

Characteristics of water

A
  • unusually high boiling point (100C @ 1atm)
  • Density of solid is less than liquid
  • high specific heat capacity
  • polar solvent
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5
Q

When 2 aqueous solutions are mixed…

A

1 - identify whether a precipitate will form. If not, no reaction.
2- write a MOLECULAR EQUATION - balanced equation, including states
3- write TOTAL IONIC EQUATION - spare species into anions and cations
4- Write NET IONIC EQUATION - cancel any spectator ions (dissolved ions that are in both sides of the equation)

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6
Q

What is represented by the equilibrium constant, K?

A
  • determines amount of products formed

- unitless ratio of product to reactant activities, a, at equilibrium.

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7
Q

How to calculate K for general aqueous or gas phase reactions

A

K=
concentration/pressure of products (to the power of their stoichiometric coefficients) multiplied together
divided by
concentration/pressure of reactants (to the power of their stoichiometric coefficients) multiplied together
** for gasses, P in bar
** for solutions, C in mol/L
-Don’t include solids or liquids in expressions

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8
Q

What does the magnitude of the equilibrium constant, K, tell us?

A
  • Very small: mostly reactants, reaction barely proceeds
  • Intermediate: mix of reactants/products
  • Very large: mostly products, reactions goes to completion
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9
Q

what is Kow?

A

Octanol-water partition coefficient
measures the lithophilicity/hydrophobicity of a solute
Large Kow and log(Kow) = highly lithophilic/hydrophobic

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10
Q

3 characteristics of Persistent Organic Pollutants (POPs)

A
  • Persistant (resist transformation)
  • Toxic (ex. carcinogen)
  • Bioaccumulate (concentration in fatty tissues) - log(Kow) used to measure this
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11
Q

Define Le Châtelier’s principle

A

When an equilibrium system is subject to stress, system responds by attainting a NEW EQUILIBRIUM that partially offsets the stress.
STRESS = change in temperature, pressure, concentration of a reactant or product

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12
Q

How does change in volume effect a system at equilibrium?

A

REDUCE V/increase partial P = favours direction that produces LESS moles of gas
INCREASE V/decrease partial P = favours direction that produces MORE moles of gas

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13
Q

How does change in temperature effect a system at equilibrium?

A

RAISE T = favours direction of ENDOTHERMIC reaction
LOWER T = favours direction of EXOTHERMIC reaction
NOTE
Equilibrium constants change with temperature

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14
Q

Define Q

A
  • reaction quotient
  • ratio of products to reactants at any given instant
  • not a constant , can take on any value
  • calculated the same way as K, but with the current pressure or concentrations in the reaction
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15
Q

Describe the effects of different relationships between K and Q

A

Q>K reaction shifts LEFT

Q

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16
Q

ICE table method + tips

A
  • ICE (initial, change, equilibrium)
  • solve for x: the change between I and E
  • coefficient of x in C reflects coefficient of balanced chemical equation.
  • whatever side of the equation has 0 as I has POSITIVE x VALUES
  • x represents molar solubility in Ksp ICE tables
17
Q

Define Ksp

A
  • solubility product constant
  • how much a solute is dissolved in water
  • K value = 1/Ksp
18
Q

what is molar solubility

A
# of mols of a substance dissolved per L of a saturated solution
- x = molar solubility in Ksp ICE tables
19
Q

What is Qsp?

A
  • ion product

- used to help determine whether a precipitate will form by comparing it to the solubility product constant, Ksp

20
Q

What can we conclude from comparing Qsp and Ksp?

A
Same as comparing Q and K
Qsp>Ksp 
- reaction shifts LEFT
- precipitation SHOULD OCCUR
- super/saturated
Qsp