The Chemistry Knowledge for Firefighters

Natural sciences are the fields of knowledge that deal with the (systematic) study of nature and the laws of nature. Let’s distinguish physical and chemical processes and learn basic facts about models and model concepts.

If we look at a glass of water, we cannot distinguish with our eyes whether it is pure (distilled) water, salt water or sugar water. It is different when we look at a piece of granite. Here we can recognize different components. Let us take a classic look at substances, mixtures and their classification.

Depending on its temperature, a substance exists in different forms, the aggregate states. In the case of gases, the pressure also plays a role. For example, everyone knows water as a liquid, as a solid (ice) and in a gaseous state (water vapour). These different forms are called states of aggregation. In this extensive chapter, we look at the states of matter, their transitions into each other and the transport of thermal energy. We look at important safety indicators (e.g. flash point, explosion ranges), make estimates of the LEL and UEL and deal with the measuring technology of explosion ranges. In the following, we look at the heat capacity and the changes of aggregate state, in general and when using extinguishing agents.

The chapter “Gases” deals with the different gas laws, looks at the basics of diffusion, deals with critical pressure and critical temperature and their effects on firefighting operations. The chapter is rounded off with informations on the solubility of gases.

One of the early questions that natural scientists asked themselves was about the “structure of everything”. In this context, we look at the development of atomic theory, the structure of the atomic shell in various representations, and the structure of the atomic nucleus. A consideration of absolute and relative atomic masses and the introduction of the concept of the amount of substance round off the chapter.

The periodic table of the elements, also known as the periodic table or PTE for short, is something most people will remember from their school days. How this system has developed historically and what structure it is based on will be now described. Learn about periodic properties of the elements, the different represantions of the electron configuration, the main group elements and have a look on metals.

In chemical processes, no “element transformation” takes place. The atoms of the starting molecules rearrange themselves to form the molecules of the end products. In this process, bonds between the atoms are first broken and then reestablished. In order to better understand these processes, we must first agree on a uniform, suitable notation and learn the basic rules for compounds before we take a closer look at the different types of chemical bonding.

At this point we want to get an overview of the binding forces. Chemical bonds can be divided into “strong bonds” (metal binding, ion binding, electron pair binding) and “weak bonds” (dipole dipole interaction, hydrogen bond, Van der Waals forces). Let us also have a look to crystall ans molecule lattices.

Physical processes, such as the dissolution of sugar in water, are not chemical reactions. Even if a “new” substance (here: sugar water) appears to be created here, the substance-specific properties of the individual components do not change. It is merely a mixture of the individual components.Neither gold, nor other precious metals or even diamonds can be produced with a chemical reaction. One can only convert existing starting materials into new end materials.Chemical reactions always take place in a certain numerical ratio between the educts and the products. Therefore, a reaction equation can only be correct if the number of atoms of each element involved is also the same on both sides of the reaction equation.

Get information on the dissolution process itself and its temperature dependence. Learn how mixed phases (solutions and mixtures) are composed and how concentration data are related. Concentrations in the ppm range and their significance for firefighting operations round off the chapter.

Even if no chemical reaction takes place initially, new substances can still be formed when salt solutions are mixed: Double salts. In other cases, stable compounds are formed with the formation of electron pair bonds: Complexes. If “large” particles are present in the solution, these are dispersions. These groups should not be confused with each other and will be briefly addressed.

For a better understanding of acids and bases, let's take a look at the different acid-base theories, their explanations and limitations.

Before we turn to the pH value and the strength of acids and bases, first a few basic properties of these compounds and an overview of important acids and alkalis.

Let us explain to you what the pH value actually is and how it can be calculated. Learn about the strength of acids and bases and about the measurement of pH values—taking into account the conditions of emergency operations.

In the following, we will consider the reactions of acids with bases, which are generally referred to as neutralisation or neutralisation reactions. Learn the basics of neutralisation and the properties of buffer solutions. Special attention is paid to the topic “Neutralisation in emergency operations”.

In this chapter you will learn about the (simultaneous) processes of oxidation and reduction. Different types of redox reactions are considered and the analogies to acid-base reactions are shown. At the end you will learn how to set up redox equations.

Let us now consider electrochemical half-cells, and the normal potential of redox couples. This leads to the electrochemical voltage series and allows predictions about the course of the reaction.

The difference between the redox potentials of two half cells is the maximum voltage that a galvanic cell can deliver. It is called the electromotive force (EMF).

Let's have a closer look to batteries, accumulators an the phenomena of electrochemical corrosion.

If an electric current is passed through a substance or its solution and chemical changes take place, this is commonly referred to as electrolysis. Electrolysis is more or less the reverse of the processes that occur when a battery or accumulator is discharged. It can also be said that the charging of an accumulator represents electrolysis.

Before we familiarize ourselves with the actual processes of radioactivity, let us first take a look at the concept of radiation. Here we want to distinguish between particle radiation and wave radiation. For electromagnetic wave radiation, the relationship between energy, frequency and wavelength will also be explained.

Let's have a short look to the history of Radioactivity.

You will get an overview of the notations in nuclear chemistry and explanations of terms for nuclides and isotopes.

Radioactivity comes exclusively from the atomic nucleus. Here, the nucleus gives off energy in the form of particles or radiation. Before we turn to radioactive decay, we must first understand the structure of the atomic nucleus. We look at the two essential nuclear models, the forces that prevail in the atomic nucleus and the stability of the atomic nucleus.

Let us now turn to the original radioactivity. We want to take a closer look at the individual emitted “types of radiation” and their properties.

Nuclide maps are overviews related to the periodic table, in which all nuclides and their decays or decay types are shown. Let's have a look to these charts.

Due to the historical development, a multitude of units of measurement for radioactivity, ionizing radiation and their interactions has resulted. We will first look at the units commonly used today. Subsequently, the units which are no longer in use will be briefly explained.

This section provides an overview of the basic measuring principles of radiation measuring instruments. Furthermore, the different device groups are presented and instructions for their use are given.

With regard to human exposure to radioactive substances, a fundamental distinction must be made between natural radioactivity and the additional radiation exposure caused by civilization. We will now take a closer look at this.

It is generally known that the ionising radiation emitted by radioactive substances can damage living cells. The biological (harmful) effect of radiation involves complex chains of biological processes at the molecular level, which are presented below in a simplified form.

Radionuclides, or the radiation they emit, have many applications. Some important applications in science, technology, and medicine are briefly addressed. Most people are probably not aware of the many ways in which radioactive substances are used in everyday life. Therefore let's have a closer look.

Without the transformation of hydrogen into helium and all heavier elements in the course of the history of the formation of our universe, we would not be here today. The formation of all elements, with the exception of hydrogen, is exclusively due to nuclear reactions. Nuclear reactions also take place in our atmosphere, triggered by cosmic rays. Today, man is also capable of triggering such reactions.

With regard to labelling, a distinction must be made not only between transport regulations and regulations of chemicals, as is the case with “purely chemical” hazardous substances. In addition, regulations on the labelling of workplaces in which radioactive materials are handled must be observed.

Naturally, there is no “radiation protection suit” for gamma radiation. First and foremost, the protective clothing or the contamination suit protects against α-radiation. The greatest and best protection, however, is provided by the correct behavior during operations with radioactive materials. These behavioral measures are described and explained below.

Energy (Greek energeia = acting force) is the “ability to do work”. Let us look at the “law of conservation of energy”, the (chemical) reaction energy, enthalpy, entropy and thus the driving force behind chemical reactions. Activation energy, the Hess theorem and the Born-Haber cycle are also considered.

It is estimated that 90 % of chemical products are produced using catalysts in at least one manufacturing step. In addition, many technical processes depend on catalysts, such as exhaust gas purification in motor vehicles. Let us therefore take a brief look at how catalysts work and also consider energy conversion. Inhibitors (“anti-catalysts”) and catalyst poisons are also not left unmentioned.

A brief overview of “fire as an oxidation process”.

Burning is a (natural) phenomenon that has been known since time immemorial. The use of fire has significantly influenced our development and our cultural history. Important steps in technology are also connected with fire. Let us first deal with the prerequisites of the burning process and then look in detail at the influence of: the combustible material, oxygen, the ignition energy, the mixing ratio and the “fire catalyst”. The combustion equation and information on the fire behaviour of building materials and components round off the chapter.

We first differentiate explosion events according to the cause of the explosion and then deal with explosion characteristics.

Combustion processes seem quite simple at first glance. If the molecular formula of the combustible substance is known, the reaction equation can be quickly established and the matter is settled. Carbon becomes CO2, hydrogen becomes H2O. And incomplete combustion, i.e. when there is too little oxygen, produces carbon monoxide. The course of combustion reactions is nevertheless one of the most complex chemical reactions. The elucidation of the detailed chemical sequence of combustion processes is an important task for technology. In the context of “technical combustion”, processes in combustion plants and combustion engines are optimized. Let us venture a deeper insight into the topic.

Learn more about extinguishing methods and procedures. The extinguishing agents are considered in terms of their effect and their application limits. The chapter is rounded off with information on firefighting operations.

Flame retardants are important components in plastics of all kinds and in construction. You will get an overview of different flame retardants and their mode of action, as well as intuminescent coatings.

So-called “organic chemistry” is the part of chemistry that has the most far-reaching and visible impact on our lives. Millions of people are cured (medicines), clothed (synthetic fibres, dyes) and fed (pesticides) without realising the importance of this branch of chemistry. In our daily lives we encounter another multitude of their products: Plastics of all kinds, detergents and cleaners, cosmetics, composites, paints and coatings, fragrances in perfumes, dyes in displays, LEDs in lamps, and many more. Motor fuels (gasoline, diesel, liquefied petroleum gas, kerosene) and heating fuels (natural gas, heating oil) are also included in this area, as are natural substances, which are mostly obtained from plants but are also produced synthetically to a large extent. Let us briefly explain why carbon, of all things, is the basis here.

Hydrocarbons (HCs), i.e. compounds composed only of carbon and hydrogen, are the simplest organic compounds. They can occur as linear or branched chain molecules, as closed ring structures or as so-called aromatic compounds. Let us additionally take a look at the bonds at the C atom.

A large number of organic compounds of industrial importance are halogenated hydrocarbons. Let us have a look on thr “dirty dozen” of organic halogen compounds.

A short overview on organic oxygen compounds.

A short overview on organic nitrogen compounds.

A short overview on organic sulphur compounds.

Get an overview of the most important plastics, their properties and manufacturing methods. Fire behaviour of plastics, smoke development and energy release are also considered.

They learn how surfactants and soaps are structured, how they work and how they form foam. With regard to fire brigade use, the change in electrical conductivity and fluorosurfactants are considered separately. Additional information on oils rounds off the chapter.

Here you will find an overview of poison effects, the labelling and classification of poisons and basic information on operational measures in firefighting operations.

This chapter describes the chemical-physical and toxicological properties of chemical warfare agents (CWA). The classification into irritants, pulmonary agents, blood agents, skin agents, nerve agents and psychotoxic agents provides a good overview. Within the groups, the most important warfare agents are listed and their properties explained. Notes on sabotage poisons, strategic warfare agents and binary CWA round off the chapter.

In this chapter you will find an overview of the types of biological agents, the hazards they pose and the associated classification.

The chapter on biological agents contains the classification of pathogens and toxins and describes also the most important bacteria, viruses and toxins.

A brief overview of explosives: hazards, labelling and operational measures in firefighting operations.