For 10 points, name this quantity with units of pressure that is defined as the tendency of a substance to escape from its current phase, symbolized by f.
For a dense fluid at high pressure, pressure affects this quantity, necessitating an exponential integral called the Poynting factor to correct it. At the same phase, temperature, and pressure, this quantity is equal in pure solutions and ideal solutions according to the Lewis-Randall rule. It also simplifies the calculation of chemical potential of a non-ideal gas to an ideal potential plus the natural log of the ratio between this and standard pressure times RT. In non-ideal gases, this quantity is equal to a coefficient, symbolized phi, multiplied by pressure, but in ideal gases it equals pressure. For 10 points, name this quantity with units of pressure that is defined as the tendency of a substance to escape from its current phase, symbolized by f.
For a dense fluid at high pressure, pressure affects this quantity, necessitating an exponential integral called the Poynting factor to correct it.
{fugacity} [prompt on ''{f}'' before it is mentioned]