### E-AIM Tutorial

 Lesson 9: Variation of Gas/aerosol Partitioning with Temperature

### 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.

### Conclusion

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.