Liquids with very low vapor pressures are often referred to as "non-volatile" liquids. These liquids have weak intermolecular forces and exhibit low tendencies to vaporize or evaporate at normal temperatures and pressures. While they may still evaporate to some extent, their evaporation rates are significantly slower compared to volatile liquids. Here are a few examples of liquids with low vapor pressures:
Glycerin: Glycerin, also known as glycerol, is a thick, syrupy liquid with a very low vapor pressure. It is commonly used in cosmetics, pharmaceuticals, and food products due to its moisturizing and sweetening properties. Glycerin evaporates very slowly, especially at room temperature and atmospheric pressure.
Silicone oils: Silicone oils, such as dimethyl silicone oil, have low vapor pressures and high thermal stability. They are commonly used in various industries, including cosmetics, lubricants, and electronics. These oils have low evaporation rates, allowing them to maintain their lubricating properties for extended periods.
Polyethylene glycol (PEG): Polyethylene glycol is a polymer with various applications, including pharmaceuticals, personal care products, and food additives. It exists in liquid form at room temperature and has a low vapor pressure. PEG's slow evaporation rate makes it useful for products requiring long-term stability.
High-viscosity oils: Certain high-viscosity oils, such as heavy mineral oil or castor oil, have low vapor pressures. They are often used as lubricants, hydraulic fluids, or in cosmetic formulations. These oils tend to evaporate slowly due to their high molecular weight and strong intermolecular forces.
While these liquids may exhibit some evaporation over time, it is typically minimal under normal conditions. The slow evaporation is attributed to their low vapor pressures, which means the equilibrium between the liquid and vapor phases is shifted towards the liquid phase at room temperature and atmospheric pressure.