Endothermic compound

These values indicate a rapid fall in thermal stability of the halide from fluorine to iodine, and hydrogen iodide is an endothermic compound. If we now examine the various enthalpy changes involved. we find the following values (in kJ) ... 

There are many compounds in existence which have a considerable positive enthalpy of formation. They are not made by direct union of the constituent elements in their standard states, but by some process in which the necessary energy is provided indirectly. Many known covalent hydrides (Chapter 5) are made by indirect methods (for example from other hydrides) or by supplying energy (in the form of heat or an electric discharge) to the direct reaction to dissociate the hydrogen molecules and also possibly vaporise the other element. Other known endothermic compounds include nitrogen oxide and ethyne (acetylene) all these compounds have considerable kinetic stability. 

Pure hydrazine is a colourless liquid, melting point 275 K, and boiling point 387 K. It is surprisingly stable for an endothermic compound = -i- 50.6 kJ mol ). Each nitrogen atom has a lone pair of electrons and either one or both nitrogen atoms are able to accept protons to give and the less stable... 

At room temperature ozone is a slightly blue diamagnetie gas which condenses to a deep blue liquid. It has a characteristic smell, and is toxic. Ozone is a very endothermic compound ... 

Most chemical reactions are exothermic. In the few endothermic reactions that are known, heat is absorbed into the reaction product or products, which are known as endothermic or energy-rich compounds. Such compounds are thermodynamically unstable because heat woiild be released on decomposition of their elements. The majority of endothermic compounds possess a tendency toward insta-bihty and possibly explosive decomposition under various circumstances of initiation. 

Test suspect materials for undesired properties, (e.g., endothermic compounds, compounds containing oxidizing and reducing group such as ammonium nitrate)... 

Besides the weak bonds listed in the previous table, there are other multiple bonds that endow the molecules in which they are situated with a positive enthalpy of formation. Such compounds are termed endothermic compounds. The danger they represent does not necessarily come from the fact that they are unstable, but is related to the exothermicity of their decomposition reaction. The most convincing examples are the acetylenic compounds, and in particular, acetylene. It is also the case for ethylene, aromatic compounds, imines and nitriles. 

The tetroxide, which forms an equilibrium with nitrogen dioxide, is a very strong oxidant and an endothermic compound. To analyse all the dangerous reactions of... 

An endothermic compound, which is hardiy stable thermodynamically. However, it only decomposes under extreme conditions (very violent shock, high temperature). When it is involved in a reaction, this compound can combust or detonate easily because of the exothermicity of the transformation. Since it is hardly ever handled in the pure state (it forms when compounds containing arsenic are handled) it gives rise to a limited number of accidents. 

Propargyl bromide is an endothermic compound. It detonates on impact or when it is heated. When 70-80% of it is present in a solution with toluene It becomes insensitive to impact. 

Endothermic compounds, formed as the energy-rich products of endothermic reactions, are thermodynamically unstable and may be liable to energetic decomposition with low energy of activation. 

See other endothermic compounds, metal azides, silver compounds 0024. Silver trisulfurpentanitridate... 

Gold(HI) oxide [1303-58-8] Au203 Ammoniiun salts See Gold(III) chloride Ammonia, etc. See other endothermic compounds, gold compounds Au203... 

Though a moderately endothermic compound (AH°f +70.8 kJ/mol), its high MW gives it the rather low specific energy content of 0.18 kJ/g. 

The material is impact-sensitive when dry and is supplied and stored damp with ethanol. It is used as a saturated solution and it is important to prevent total evaporation, or the slow growth of large crystals which may become dried and shock-sensitive. Lead drains must not be used, to avoid formation of the detonator, lead azide. Exposure to acid conditions may generate explosive hydrazoic acid [1], It has been stated that barium azide is relatively insensitive to impact but highly sensitive to friction [2], Strontium, and particularly calcium azides show much more marked explosive properties than barium azide. The explosive properties appear to be closely associated with the method of formation of the azide [3], Factors which affect the sensitivity of the azide include surface area, solvent used and ageing. Presence of barium metal, sodium or iron ions as impurities increases the sensitivity [4], Though not an endothermic compound (AH°f —22.17 kJ/mol, 0.1 kj/g), it may thermally decompose to barium nitride, rather than to the elements, when a considerable exotherm is produced (98.74 kJ/mol, 0.45 kJ/g of azide) [5]. 

See Other ENDOTHERMIC COMPOUNDS, METAL CYANIDES, SILVER COMPOUNDS... 

See other cyano compounds endothermic compounds, organic acids... 

Explosions occurred dining distillation of this polynitro compound [1]. Though not an endothermic compound, it is of positive oxygen balance and the heat of decomposition (2.80 kJ/g) would give an adiabatic decomposition temperature exceeding 2200°C and a 40-fold increase in pressure [2],... 

A moderately endothermic compound (AH°f (1) +53.1 kJ/mol, 1.29 kJ/g) which, though reactive, does not exhibit inherent instability under normal conditions. 

See related cyano compounds See other ENDOTHERMIC COMPOUNDS... 

On exposure to air, dimethylcadmium peroxide is formed as a crust [1] which explodes on friction [2], Ignition of dimethylcadmium may occur if a large area volume ratio is involved, as when it is dripped onto filter paper [3], It is a mildly endothermic compound (AH°f (1) +67.8 kJ/mol, 0.47 kJ/g). 

See other alkylmetals, endothermic compounds, mercury compounds... 

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