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16 Cards in this Set
- Front
- Back
Surface tension?
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Force per unit length of interface (Nm-1)
Free energy required to create new SA (Jm-2) |
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Surface energy?
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Surface tension x SA
Energy of physical changes of droplets with r less than 10nm |
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SA of droplet?
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4 pi r^2
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Laplace equation?
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delta P = (2xsurface tension)/radius
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Inside a droplet liquid is at ____ pressure than vapour due to ____?
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Inside a droplet liquid is at higher pressure than vapour due to surface tension
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Vapour pressure increases as droplet size___?
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decreases
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Ostwald ripening?
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small drops shrink, large drops grow
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What happens if r<rc?
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liquid drop vapourises
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What happens if r > or = rc?
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liquid drop grows (condensation)
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Homogenous nucleation?
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Raise T or P so barrier to nucleation is roughly KbT, random fluctuations in concentration generate sufficently large nuclei
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Heterogenous nucleation?
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Condense on pre-existing nuclei (i.e. dust, impurities)
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Contact angle for partial wetting?
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0<theta<180
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Contact angle for dewetting?
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180
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Contact angle for wetting?
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0
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Final surface energy?
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Surface tension SL + LV
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To wet surface final surface energy must be lower than___?
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initial surface energy, surface tension SV
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