Solid-Liquid, Liquid – Gas and Solid-Gas Equilibria

Introduction

Equilibrium covers the core part of chemistry, and almost all the topics have their mention in one or the other form. This is a crucial topic for the complete course. Now, come on board and get ready to move forward towards the bright light of success. 

Overview

The chemical properties of any element allow the equilibrium process to bring the molecules into a balancing state and equal charge. Similarly, the solid liquid equilibria and other phases undergo certain variations that change their molecular calculations in physical properties. Despite changing the molecular balance of elements, there is no change in the chemical formulation of the elements. 

The element undergoing this also records no change in their functioning and reacting properties. When the equilibrium goes through the phase of balancing the molecules, several examples of solid-liquid equilibrium represents the transformation that undergoes these procedures:

Solid ⇌ Liquid

Liquid ⇌ Gas

Solid ⇌ Gas

There is a record of distinct changes in elements’ molecular and chemical phases during this transformation. The transformations have the basis of temperature, nature, and reacting properties of the elements. Therefore, there are no noticeable changes in the elements after attaining the equilibrium state. Hence, the process of solid liquid equilibria and others may show the results in visible and invisible formats.

Let’s understand all the phases of equilibrium in the categorical format:

• Solid-liquid equilibrium

We all know that the process of equilibrium is not a static procedure. This is because an intense activity is going on under the borders of the element’s solid liquid equilibrium during this process. When ice and water attain placement under the temperature of 237 k in a Thermo flask, there is an intense change in their appearance. The water molecules transform into a solid form during the equilibrium process, whereas the molecules present in ice meltdown to the liquid. These processes undergo in the same interval of time, and there is no loss of molecular mass of both the elements. 

In such examples of solid-liquid equilibrium, there must be a particular amount of pressure and temperature that react on both the elements in the same way to reach the position of equilibrium. At this moment, the rate of change of freezing point of water is equal to the rate of change of melting point of ice. The process somehow differs itself in the liquid gas equilibrium. But the procedure to match the rate of change of molecular properties at an inaccurate point of time is the same in each process and element.

Reason:

• The opposing procedures in both the elements occur at the same time and interval. 
• The transformation occurring during solid liquid equilibria is at the same rate and keeps the value of both water and ice constant.

• Liquid gas equilibrium

In this process, to reach the state of liquid gas equilibria, the process of equilibrium goes with the slight charge of difference. This type of equilibrium results in the rate of change of evaporation equalizing with the rate of change of condensation.

For example, let us understand it by placing drying agent anhydrous calcium chloride with a manometer (tubular device containing U shape tube with mercury) in a compact container. The manometer will soak all the moisture from the drying agent. After a few hours, remove the drying agent by tilting the box in the Petri dish with water. 

This equilibrium process starts with the increase in pressure in the container, and water in the Petri dish condenses in the form of vapor. The mercury present in the manometer rises to reach the constant value where the pressure and temperature in the container and Petri dish reach an equal point. As in the solid liquid equilibria, the rate of change of evaporation equals the rate of condensation change under the particular temperature and pressure.

Reason:

• The pressure during evaporation of water molecules under certain time pressure remains constant.
• The equilibrium balances in the state where both the elements are neither entirely in the evaporation state nor the condensation state. The element reaches some state and position in the solid, liquid equilibrium, but in a slightly different and uncertain situation.

• Solid equilibrium

In this kind of equilibrium, the state of equilibrium changes in appearance and properties. The liquid gas and solid liquid equilibria have distinct characteristics with the element that undergoes such equilibrium. In this type, the rate of change of sublimation is equal to the rate of deposition change. 

The particular interval of time in which the elements match the vapor and solid-state is their equilibrium points. This means that the element sublimes into the vapor formation, and vapor acquires the solid-state to reach a state of equilibrium. Many examples are undergoing this type of equilibrium. Iodine (I2), camphor, and NH4Cl are some basic examples. 

The solid liquid equilibria and the following equilibrium undergo many changes to balance the molecules of the elements.

Reason:

• The condensation process starts in it because of the existing moisture in the element, and thus, it sublimes into vapor.
• The vaporization undergoes the deposition to solidify the vapors or moisture present in the element, and thus it forms a solid format with vapor.

Conclusion

These are all the details about each aspect of the solid liquid equilibria and its relative topics, essential for the exams. In all the competitive exams this topic consists of the top portion of the exam paper.