Question

Standard state refers to (a) one atmosphere pressure and \(25^{\circ} \mathrm{C}\) temperature (b) one atmosphere pressure and \(100^{\circ} \mathrm{C}\) temperature (c) one atmosphere pressure and \(0^{\circ} \mathrm{C}\) temperature (d) none of these

Short answer

The standard state usually refers to one atmosphere pressure and \(25^{\circ} \mathrm{C}\) temperature, hence the correct answer is option (a).

Step-by-step solution

Understanding Standard State

The term 'Standard State' is a reference used to describe the standard conditions at which a certain physical or chemical process takes place. These conditions are usually a set temperature and pressure.

Identifying the Standard State Conditions

In chemistry, the standard state conditions are usually one atmosphere pressure.This is commonly agreed upon. The difference comes in the temperature, with some considering it to be \(0^{\circ} \mathrm{C}\) and others \(25^{\circ} \mathrm{C}\). This difference actually stems from the difference between the IUPAC (International Union of Pure and Applied Chemistry) definition and the US definition.

Choosing the Correct Answer

The IUPAC standard temperature is \(0^{\circ} \mathrm{C}\), but for practical purposes and in the majority of literature, \(25^{\circ} \mathrm{C}\) or 'room temperature' is considered. Therefore, option (a) one atmosphere pressure and \(25^{\circ} \mathrm{C}\) temperature is the most commonly accepted answer.

Key concepts

Chemistry

Chemistry is often referred to as the 'central science' because it connects physical sciences with life sciences and applied sciences like medicine and engineering. Understanding the basics of chemistry is essential for comprehension of the natural world, as it explains how matter acts on a molecular level and how chemical reactions occur.

A fundamental aspect of chemistry is studying reactions under specific conditions, which leads us towards the concept of the 'standard state'. This term is used to describe a set of conditions of temperature, pressure, and concentration under which substances' properties are measured and reported. Scientists have agreed on these conditions so that they can compare the properties of substances uniformly, without the variability introduced by different environmental factors.

IUPAC Standard Temperature

The International Union of Pure and Applied Chemistry, or IUPAC, has established conventions for standard state conditions to provide consistency across the field. When we refer to IUPAC standard temperature in chemistry, we're talking about a baseline temperature of exactly \(0^{\circ} \mathrm{C}\) or 273.15 K.

This standard is pivotal when considering physical and chemical properties like melting point, boiling point, vapor pressure, and when calculating thermodynamic properties such as enthalpy, entropy, and Gibbs free energy. However, for practicality and relatability in daily laboratory work, it's often the case that room temperature, defined as \(25^{\circ} \mathrm{C}\) or 298.15 K, is utilized instead. This is because most laboratories operate around this temperature, making it more relevant for experimental procedures.

Physical Chemistry

Physical chemistry sits at the crossroads between physics and chemistry, focusing on the understanding of the physical properties of molecules, the forces that act upon them, and the dynamics of their interactions. This branch of chemistry relies heavily on standard state conditions to predict the behavior of materials and reactions.

For instance, the thermodynamic principles that govern how chemical processes occur under certain conditions and how they are influenced by temperature, pressure, and concentration are extensively studied within physical chemistry. By adhering to standard state conditions, physical chemists can more accurately model systems, simulate potential outcomes, and calculate fundamental thermodynamic quantities which are essential for the design and synthesis of new materials and pharmaceuticals.