Question

What is a pressure of $101.3{\text{ }}kPa$ equal to?

Answer 1

Pressure is defined as the force applied perpendicular to the surface of any object per unit area. The SI unit of pressure is pascal $(Pa)$. One pascal is equal to one newton per square metre ($N/{m^2}$ or $kg.{m^{ - 1}}.{s^{ - 2}}$)

Complete answer:
A pressure of $101.3{\text{ }}kPa$ is equal to $1{\text{ }}atm$. Here, $atm$ refers to the unit of standard atmospheric pressure. Standard atmospheric pressure is an established constant. Other units of standard pressure are $760mmHg$or $torr$.
Hence, we can say that a pressure of $101.3{\text{ }}kPa$ is equal to $1{\text{ }}atm$, $760mmHg$or ${\text{759}}{\text{.81 }}torr$.
The absence of pressure is vacuum. Pressure is usually measured using a barometer. In chemistry, the standard temperature and pressure is used. Here, standard temperature is equal to $25^\circ C$ or $298.15K$ and standard pressure is equal to $1{\text{ }}Atm,{\text{ }}101.3kPa$ or $760{\text{ }}mmHg$.
STP is the "standard" condition often used for measuring gas density and volume. At STP, $1$ mole of any gas occupies $22.4L$.
The most used standards are of the International Union of Pure and Applied Chemistry (IUPAC). However, the value of STP is not universally accepted and many other organizations have established a variety of alternative definitions for their standard reference conditions.

Note:
STP should not be confused with the standard state commonly used in thermodynamic evaluations of the Gibbs energy of a reaction. In many technical publications, STP is simply stated as “standard conditions” or often substituted with the older “normal conditions”. In special cases this can lead to confusion and errors. Good practice always incorporates the reference conditions of temperature and pressure. If not stated, some room environment conditions are supposed, close to $1{\text{ }}Atm$ pressure, $298K$ $(25^\circ C)$, and $0\%$ humidity.