Volatile vs Nonvolatile
Conversion from a liquid phase to the gaseous phase can take place in different paths like evaporation or vaporization at the boiling point. Evaporation is the process of changing a liquid into its vapor stage. The word “evaporation” is specifically used when the vaporization happens from the surface of the liquid. Liquid vaporization can also happen at the boiling point where evaporation happens from whole liquid mass, but then it is not called as evaporation. Evaporation can be influenced by various factors like concentration of other substances in the air, surface area, pressure, temperature of the substance, density, flow rate of air etc. Distillation is a physical separation method which is used to separate compounds from a mixture. It is based on the boiling points of the components in the mixture. When a mixture has different component with different boiling points, they evaporate at different times when we are heating. This principle is used in the distillation technique. If there are two substances in the mixture as A and B, we will assume A has the higher boiling point. In that case, when boiling, A will evaporate slower than B; therefore, the vapor will have a higher amount of B than A. So the proportions of A and B in the vapor phase are different from the proportions in the liquid mixture. The conclusion is that, the most volatile substances will be separated from the original mixture whereas less volatile substances will be remained in the original mixture.
Volatility is the tendency of a substance to vaporize. Volatile substances have the capability to go into the vapor phase. This may happen during heating or without heating. Volatility and the vapor pressure of a substance are related. If the volatility is high, the vapor pressure is also high. If the volatility is low, then the vapor pressure is low. Normally liquids are volatile. They tend to go into the vapor phase rapidly. For example, acetone, hexane, chloroform are volatile liquids, which evaporates rapidly. Moreover, there are some solids which can go directly into the vapor phase without going through the liquid phase. This is known as sublimation.
Non volatile substances are substances which do not vaporize rapidly. They don’t have a higher vapor pressure at the normal room temperature and pressure. Nonvolatile substances will mostly be as solids in the room temperature. Sodium chloride, silver nitrate are nonvolatile compounds. When nonvolatile compounds are mixed with volatile liquids such as water it is easy to separate them by evaporation. Then the volatile liquid will be evaporated leaving the nonvolatile solid at the bottom of the container.
What is the difference between Volatile and Nonvolatile Substances?
• Volatile substances have a tendency to vaporize whereas nonvolatile substances do not have a tendency to vaporize.
• Volatile substances have a high vapor pressure at normal room temperature and pressure. Nonvolatile substances do not have a high vapor pressure in these conditions.
• When volatile liquids are heated or stored in an open container, the volume of it decreases but this doesn’t happen to nonvolatile liquids.
• Volatile substances are generally highly flammable compared to nonvolatile substances.
• Volatile substances can be easily detected by the smell compared to the nonvolatile substances.