Introduction
In
Lesson 8, we studied the temperature dependence of the deliquescence
points of two salts. Here, we
investigate the effect of temperature upon the partitioning
of volatile compounds between gas, liquid and solid phases.
Preparation
Before starting, ensure that this browser window occupies only the
left half of your screen. You should leave enough
space for another browser window where you can
enter data into
E-AIM and read the results. If your screen is too small for
two windows, print out this tutorial and use this window to run the
E-AIM model. In these lessons we assume that you will
have two browser windows open.
Select this
link to open a second browser window containing the data
input page for "variable temperature" calculations
using Model II (http://www.aim.env.uea.ac.uk/aim/model2/mod2t.php). Arrange
the windows on your screen so that both are visible and the left window
contains this text.
The Lesson
There is only a single part to this lesson, in which the influence of temperature
on the equilibrium
state of a system including gas, solid and aqueous phases is examined.
You have completed Lesson 9, and learned that:
- The existence and physical
state of a particle phase (solid or liquid) can be determined entirely
by temperature even for a system of very simple composition.
- The volatility of ammonia and nitric acid increase with temperature,
and it is only in the lower temperatures of the range that we find a
particle phase.
- The deliquescence relative humidity of solid NH4NO3(s)
increases steeply with temperature and is equal to the ambient relative
humidity of 70% at about 284 K. At this temperature the solid particle
takes up water and becomes a completely liquid droplet.
- At temperatures above about 300 K the amount of material (water, and ions)
in the liquid droplet decreases as NH3 and HNO3
become more volatile and transfer to the gas phase. Eventually, at about
315 K the particle completely evaporates and only gaseous ammonia and nitric
acid remain.
This is the last of the E-AIM lessons. Please return to the
Tutorial home page.