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Yes, but rather: 'most of all' combination reactions are exothermic. This is mostly true for spontaneous, common reactions.
Examples of the contrary endothermic reactions, though rare, are:
The formation reaction (= combination 'pur sang') of ethene, propene, acetylene, and even benzene is endothermic, when combined out of elements (that's why they are called endothermic compounds). Further a lot of metal hydride's, chlorous oxide: ClO2 are endothermic.
The most Exceptional Endothermic Compound is:
Dicyanoacetylene, IUPAC-name: but-2-ynedinitrile, C4N2 (or more structural: NC-CC-CN)
Standard heat of formation Ho298 ( 4C + N2 --> ) is 500.4 kJ/mol
Because of its high endothermic heat of formation, it can explode to carbon powder and nitrogen gas (reversed formation reaction, exo. 500.4 kJ/mol).
It burns in oxygen with a bright blue-white flame at a temperature of 5260 K, which is probably the hottest flame of any chemical.
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What is meant by the term chemical change Give 2 examples?
A chemical change is a change that imply the change of the nature of molecules. Examples: neutralization of an acidic solution, thermal decomposition and generally all chemical reactions.
Is shooting off fireworks a physical change?
yes, shooting off fireworks is a chemical change because decomposition reactions occur and the nature of the initial chemicals is changed.
How will you judge whether a chemical reaction is exothermic or endothermic in nature?
ty
What is the name for thermal energy that is transfered only from a higher temperature to a lower temperature?
All thermal energy flows from high temperature objects to low temperature objects. This is the nature of thermal energy.
Which are more in nature reversible or irreversible chemical reactions?
irreversible
What is meant by the term chemical change Give 2 examples?
A chemical change is a change that imply the change of the nature of molecules. Examples: neutralization of an acidic solution, thermal decomposition and generally all chemical reactions.
Is shooting off fireworks a physical change?
yes, shooting off fireworks is a chemical change because decomposition reactions occur and the nature of the initial chemicals is changed.
How will you judge whether a chemical reaction is exothermic or endothermic in nature?
ty
What useful reactions do you look for?
give four examples of reactions in nature and write the word equation for each give four examples of reactions in nature and write the word equation for each give four examples of reactions in nature and write the word equation for each
Is decomposition reaction a chemical reaction?
It depends on the nature of the decomposition. if you are talking about biodegradeability in a substance, then no, its decomposition is mainly due to bacteria that will break down the various particles in the substance ("eat" them). There are, however certain chemical reactions which take place within the bacteria as the substance is being broken down, (much like those that happen in the human body) and the possibility of there being other products in the vicinity which may react to the substance (and degrade it) is always present. It could be said that decomposition is therefore a chemical reaction (or rather a series thereof), but with biodegradeability in mind it is not generally thought of as such.
The majority of spontaneous chemical reactions in nature are?
exothermic
What is the name for thermal energy that is transfered only from a higher temperature to a lower temperature?
All thermal energy flows from high temperature objects to low temperature objects. This is the nature of thermal energy.
What is the advantage of the stepwise nature of the reactions of cell respiration?
The series of reactions transfers the energy of glucose to ATP.
Which are more in nature reversible or irreversible chemical reactions?
irreversible
Is alcohol evaporation endothermic or exothermic?
Always endothermic. Liquids absorb heat from the surroundings through evaporation, and keeps continuing this to regain lost energy. This produces a cooling effect in the surroundings.
Why Thermal stability increases when going down the group?
as metallic nature decreses
Why electron affinity of dinegative ion is endothermic?
Di-Negative atoms are already electron rich in nature. This causes electron affinity is less. Since energy is needed to introduce another electron into the atom the process is endothermic.
