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