Calorimetry

the discovery of certain thermal properties of substances such as calorific value, specific heat or latent heat in physics and chemistry. The instrument used is called a calorimeter and it consists essentially of apparatus which allows the substance to be burnt and the heat transferred to a surrounding body of water, enabling the rise in temperature and therefore the heat output to be measured.

Taken from Dictionary of Science

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Calorimetry is the science of measuring the heat of chemical reactions or physical changes. Calorimetry involves the use of a calorimeter. The word calorimetry is derived from the Latin word calor, meaning heat. Scottish physician and scientist Joseph Black, who was the first to recognize the distinction between heat and temperature, is said to be the founder of calorimetry.

Indirect calorimetry calculates heat that living organisms produce from their production of carbon dioxide and nitrogen waste (frequently ammonia in aquatic organisms, or urea in terrestrial ones), OR from their consumption of oxygen. Lavoisier noted in 1780 that heat production can be predicted from oxygen consumption this way, using multiple regression. The Dynamic Energy Budget theory explains why this procedure is correct. Of course, heat generated by living organisms may also be measured by direct calorimetry, in which the entire organism is placed inside the calorimeter for the measurement.

The specific heat formula is as follows:

where

q is energy, or heat,

m is mass,

c is specific heat capacity,

ΔT is change in temperature.

Taken from Wikipedia

Radioactivity

the giving out of particles (known as α or β particles and γ rays) by unstable substances that are disintegrating.

Taken from Dictionary of Science

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Radioactive decay is the process in which an unstable atomic nucleus spontaneously loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type, called the parent nuclide transforming to an atom of a different type, named the daughter nuclide. For example: a carbon-14 atom (the "parent") emits radiation and transforms to a nitrogen-14 atom (the "daughter"). This is a stochastic process on the atomic level, in that it is impossible to predict when a given atom will decay, but given a large number of similar atoms the decay rate, on average, is predictable.

The SI unit of activity is the becquerel (Bq). One Bq is defined as one transformation (or decay) per second. Since any reasonably-sized sample of radioactive material contains many atoms, a Bq is a tiny measure of activity; amounts on the order of GBq (gigabecquerel, 1 x 10⁹ decays per second) or TBq (terabecquerel, 1 x 10¹² decays per second) are commonly used. Another unit of radioactivity is the curie, Ci, which was originally defined as the amount of radium emanation (radon-222) in equilibrium with of one gram of pure radium, isotope Ra-226. At present it is equal, by definition, to the activity of any radionuclide decaying with a disintegration rate of 3.7 × 10¹⁰ Bq. The use of Ci is presently discouraged by the SI.

Taken from Wikipedia

Fall-out

radioactive material deposited on the ground from the atmosphere. The source of the radioactive substances is nuclear explosions or escape from nuclear reactors whether through failure to adequately filter coolants or an accident. Radioactive particles settle on material in the air and, in the case of a nuclear explosion, large quantities of dust, soil etc. are sucked up into the central plume of fire and smoke to be deposited hundreds of kilometres from the source, having first risen high in the atmosphere.

Taken from Dictionary of Science

Vacuum Distillation

distillation performed under reduced pressure. Since a reduction in pressure also reduces the boiling point of substances it means that certain substances which at normal pressures would decompose (break down), can be distilled.

Taken from Dictionary of Science

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Vacuum distillation is a method of distillation whereby the pressure above the liquid mixture to be distilled is reduced to less than its vapor pressure (usually less than atmospheric pressure) causing evaporation of the most volatile liquid(s) (those with the lowest boiling points). This distillation method works on the principle that boiling occurs when the vapor pressure of a liquid exceeds the ambient pressure. Vacuum distillation is used with or without heating the solution.

Taken from Wikipedia

Quantitative Analysis

the examination of a sample to discover the amounts of the substances present.

Taken from Dictionary of Science

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In chemistry, quantitative analysis is the determination of the absolute or relative abundance (often expressed as a concentration) of one, several or all particular substance(s) present in a sample.

Once the presence of certain substance(s) in a sample is known, the study of their absolute or relative abundance can help in determining specific properties. Knowing the composition of a sample is very important and several ways have been developed to make it possible, like gravimetric and volumetric analysis. Gravimetric analysis yields more accurate data about the composition of a sample than volumetric analysis does, but the first one takes more time to perform in the laboratory. Volumetric analysis in the other side doesn't take that much time and the results that we obtain are in the most cases satisfactory. Volumetric analysis can be simply a titration based in a neutralization reaction but it can also be a precipitation or a complex forming reaction as well as a titration based in an redox reaction. However, each method in quantitative analysis has a general specification, in neutralization reactions, for example, the reaction that occurs is between an acid and a base, which yields a salt and water, hence the name neutralization. In the precipitation reactions the standard solution is in the most cases silver nitrate which is used as a reagent to react with the ions present in the sample and to form a high insoluble precipitate. Precipitation methods are often called simply as Argentometry. In the two other methods the situation is the same. Complex forming titration is a reaction that occurs between metal ions and a standard solution that is in the most cases EDTA (ethylene diamine tetra acetic acid). In the redox titration that reaction is carried out between an oxidizing agent and a reduction agent.

For example, quantitative analysis performed by mass spectrometry on biological samples can determine, by the relative abundance ratio of specific proteins, indications of certain diseases, like cancer.

Taken from Wikipedia

Qualitative Analysis

the chemical examination of a sample to discover what substances are present.

Taken from Dictionary of Science

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In the qualitative analysis procedure, the chemical properties of an unknown substance are determined by systematically reacting the unknown with a number of different reagents. By predetermining what the particular reaction will produce if a specific ion is present, the ions that actually are in the solution can be identified. For example, if a reaction is known to produce a precipitate if ion A is present and a precipitate is formed when the reaction is run, then ion A may be present in solution (there may be, and usually are, other ions that will also precipitate with a particular reagent). If no precipitate is formed when the reaction is run, then ion A is clearly not present in the unknown solution and a different reaction will have to be run to determine what ions are present.

There are two general situations in which qualitative analysis is used - in the identification of a simple salt, or the identification of multiple cations in a solution.

Taken from Wired Chemist