ebooksgratis.com

See also ebooksgratis.com: no banners, no cookies, totally FREE.

CLASSICISTRANIERI HOME PAGE - YOUTUBE CHANNEL
Privacy Policy Cookie Policy Terms and Conditions
Kelvin equation - Wikipedia, the free encyclopedia

Kelvin equation

From Wikipedia, the free encyclopedia

Kelvin equation describes the change of vapour pressure over liquid curved with a radius r (for example, in a capillary or over a droplet). The Kelvin equation is used for determination of pore size distribution of a porous medium using adsorption porosimetry.

The Kelvin equation may be written in the form

\ln {p \over p_0}= {2 \gamma V_m \over rRT}

where p is the actual vapour pressure, p0 is the saturated vapour pressure, γ is the surface tension, Vm is the molar volume, R is the universal gas constant, r is the radius of the droplet, and T is temperature.

Equilibrium vapor pressure depends on droplet size. If p0 < p, then liquid evaporates from the droplets.

If p0 > p, then the gas condenses onto the droplets increasing their volumes.

As r increases, p decreases and the droplets grow into bulk liquid.

If we now cool the vapour, then T decreases, but so does p0. This means p / p0 increases as the liquid is cooled. We can treat γ and V as approximately fixed, which means that the critical radius r must also decrease. The further a vapour is supercooled, the smaller the critical radius becomes. Ultimately it gets as small as a few molecules and the liquid undergoes homogeneous nucleation and growth.

[edit] See also

[edit] References

  • W. T. Thomson, Phil. Mag. 42, 448 (1871)
  • S. J. Gregg and K. S. W. Sing, Adsorption, Surface Area and Porosity, 2nd edition, Academic Press, New York, (1982) p.121
  • Adamson and Gast, Physical Chemistry of Surfaces, 6th edition, (1997) p.54



aa - ab - af - ak - als - am - an - ang - ar - arc - as - ast - av - ay - az - ba - bar - bat_smg - bcl - be - be_x_old - bg - bh - bi - bm - bn - bo - bpy - br - bs - bug - bxr - ca - cbk_zam - cdo - ce - ceb - ch - cho - chr - chy - co - cr - crh - cs - csb - cu - cv - cy - da - de - diq - dsb - dv - dz - ee - el - eml - en - eo - es - et - eu - ext - fa - ff - fi - fiu_vro - fj - fo - fr - frp - fur - fy - ga - gan - gd - gl - glk - gn - got - gu - gv - ha - hak - haw - he - hi - hif - ho - hr - hsb - ht - hu - hy - hz - ia - id - ie - ig - ii - ik - ilo - io - is - it - iu - ja - jbo - jv - ka - kaa - kab - kg - ki - kj - kk - kl - km - kn - ko - kr - ks - ksh - ku - kv - kw - ky - la - lad - lb - lbe - lg - li - lij - lmo - ln - lo - lt - lv - map_bms - mdf - mg - mh - mi - mk - ml - mn - mo - mr - mt - mus - my - myv - mzn - na - nah - nap - nds - nds_nl - ne - new - ng - nl - nn - no - nov - nrm - nv - ny - oc - om - or - os - pa - pag - pam - pap - pdc - pi - pih - pl - pms - ps - pt - qu - quality - rm - rmy - rn - ro - roa_rup - roa_tara - ru - rw - sa - sah - sc - scn - sco - sd - se - sg - sh - si - simple - sk - sl - sm - sn - so - sr - srn - ss - st - stq - su - sv - sw - szl - ta - te - tet - tg - th - ti - tk - tl - tlh - tn - to - tpi - tr - ts - tt - tum - tw - ty - udm - ug - uk - ur - uz - ve - vec - vi - vls - vo - wa - war - wo - wuu - xal - xh - yi - yo - za - zea - zh - zh_classical - zh_min_nan - zh_yue - zu -