Dalton's Law

Unless individual gases chemically react with each other, the individual gases in a mixture of gases do not affect each other’s pressure. Each gas in a mixture exerts the same pressure that it would exert if it were present alone in the container. The pressure exerted by each individual gas in a mixture is called its partial pressure. This means that in a mixture containing three different gases A, B, and C, if PA is the partial pressure of gas A; PB is the partial pressure of gas B; PC is the...

The partial pressure of a gas is a measure of the thermodynamic activity of the gas's molecules. The pressure that a gas would create if it occupied the total volume available is called the gas's partial pressure. If two or more gases are mixed together in a container, the molecules move randomly and collide with each other, causing them to reach thermal equilibrium. When the gases have the same temperature, their molecules have the same average kinetic energy. Thus, each gas obeys the ideal...

Scientific Laws In science, a law is defined as a concise, verbal or mathematical, statement that summarizes a vast number of experimental observations. It describes or predicts some facets of the natural world that always remain the same under the same conditions. Scientific Theory A scientific theory is a unifying principle that provides a well-substantiated and testable explanation of aspects of nature and provides the reason for why things happen. Well-established theories are the...

Absorbance and Fluorescence When light hits a substance, it is either absorbed, transmitted, or reflected. Typically, a substance interacts with a range of wavelengths of light, each one interacting with the molecules or atoms differently. A substance may absorb a specific range of wavelengths, reflect another range of wavelengths, and transmit the other wavelengths of light. When a molecule absorbs light, the energy is used in four different ways: (1) translation, which causes the molecule to...

A pure, perfectly crystalline solid possessing no kinetic energy (that is, at a temperature of absolute zero, 0 K) may be described by a single microstate, as its purity, perfect crystallinity,and complete lack of motion means there is but one possible location for each identical atom or molecule comprising the crystal (W = 1). According to the Boltzmann equation, the entropy of this system is zero. This limiting condition for a system’s entropy represents the third law of thermodynamics: the...