Chem Chapeter 13
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Unlike interactions > Like interactions?
Unlike interactions ~~Like interactions
Unlike interactions < Like interactions:
- – endothermic overall
- – or heterogeneous mixture
When does condensation rate = evaporation rate
at vapour pressure
recrystallization rate = dissolution rate when?
at saturated solution
When does solubility increases for most ionic solids?
With increasing temperature
how is Supersaturated solution is obtained?
by coolingor concentrating a saturated solution.
Recrystallization is nucleated?
must add a few crystals of solute to initiate.
- Purify a compound fromsmall amounts ofimpurities
- • Cool the solution –desired compoundbecomessupersaturated,crystallizes.
- • Impurities areunsaturated, do notcrystallize.
Saturated Solution: maximumconcentration of dissolved solute.
rate of dissolution = rate ofcrystallization
What can fractional crystalization can be used as?
Solubility of gasses in water generally_______with increasing temperature
Why does solubility of gasses decrease with increasing temperature?
many organisms prefer cooler water.– one projected effect of global warming isa decrease in dissolved oxygen in oceans
Solubilities of gases_______with increased pressure ofthe gas above thesolvent.
What is henry's law??
C = k * Pgas
Increasing the pressure_______ the rate ofcondensation into the liquid:increased concentration.
Concentration reachesdynamic equilibrium,(evaporation rate =condensation rate) when?
C = kPgas
Solubility of CO2in water is ____under highpressure.
The vapor above an ideal solution isenriched in the more volatile component.
purify the volatile component through iterative evaporation,separation and condensation
Non-ideal solutions can lead to?
- – mixtures where the vapor and liquid phaseshave the same composition.
solvent flows across semipermeable membranes to the sidewith solute.
The pressure required to stoposmotic flow is?
the osmoticpressure: pi = MRT
Applying pressure > reversesdirection of flow: _______osmosis?
- reverses osmosis
- concentrate solutes, purify solvents.
Osmotic pressure depends on the?
- concentration of solute particles.– similar to ideal gas equation
- piV = nRT?
Lower vapour pressure leads to?
- higher boiling points.– liquid phase favoured over vapor phase
- properties of dilute solutions of non-volatile solutes that depend only on concentration, not onindividual properties• osmotic pressure
- • freezing point depression
- • boiling point elevation
What makes a substance an electrolyte?
- • conduct electricity
- • anomalous colligative properties
- • contain dissolved ions
Van’t Hoff factor?
- • i = ΔTobserved÷ΔTpredicted
- • effective moles of dissolvedparticles per mole of solute
Which affect gases more temp or pressure?
What is henry's constant?
The boiling point of a solution made of a liquid solvent with a nonvolatile solute is________than the boiling point of the pure solvent?
Boiling point of liquid is?
The temperature at which the vapour pressure of that liquid is equal to the atmospheric pressure
What are example of non electrolytes?
sugar, benzene, phenol, water
Whats i ( van't hoff factor) for nonelectrolytes?
What is an example of an electrolyte and what is its van't hoff factor?
i=2 and NaCl, KI, MgO
What is an example of a strong electrolyte and what is it Van't Hoff factor?
i=3 and MgCl2, Na2SO4
What is the equation for Boiling point elevation?
ΔTb = iKbm
- i=van't hoff factor
- Kb=boiling point elevation constant
Why is freezing point depressed?
Due to the vapour pressure lowering phenomenon
Why is th freezing point negative in the freezing point depression formula?
Because the freeing point of the solution is less than that of the pure solvent
Why do we use molality to measure the concentration of the solute?
Because molality is temperature independent
Why is a solution more difficult to freeze than the pure solvent?
Because in order to freeze a liquid it must achieve a very ordered state that results in the formation of a crystal. If there are impuritities in the liquid, ie solutes, the liquid becomes less ordered.
Freezing Point Depression formula?
- i=van't hoff factor
- Kf=boiling point elevation constant
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