Recent questions tagged thermochemistry

Description : Why a polystyrene cup is used instead of a glass beaker to find out heat of neutralization?

Last Answer : Ans: A polystyrene cup acts as an insulator therefore it will not allow heat to exchange between reaction mixture and its surroundings and enthalpy of reaction doesn’t change . On the other hand glass can easily transfer and exchange heat bringing change in enthalpy of reaction.

Description : What is the value of heat of neutralization when strong acid and base react?

Last Answer : Ans: The heat of neutralization is -57.32 kJ, when strong acid and base react.

Description : What are spectator ions?

Last Answer : During a neutralization reaction anion of acid and cation of base don’t take part in the reaction and remain in the solution .These ions are called spectater ions.

Description : Why enthalpy of water in liquid state (25 C) is less than the enthalpy of steam (100 C)?

Last Answer : Ans: Enthalpy of water in liquid state is less than steam because the steam is at high temperature i.e;100 C, whereas that of liquid water is 25 C.

Description : On which factors heat content of a system depends?

Last Answer : Ans: Heat content (enthalpy of a reaction depends upon two factors I. Physical state of reactants II. Temperature

Description : Why in endothermic reaction we have to provide heat to the system?

Last Answer : Ans: In endothermic reactions the energy of the products is more than that of the reactants, so in order to form the product we have to provide energy to the system.

Description : What is the effect of endothermic and exothermic reactions on temperature of surroundings.

Last Answer : Ans: In endothermic reactions heat is absorbed from the surroundings resulting in decrease of temperature. Whereas heat is evolved in surrounding during exothermic reaction so temperature of surroundings increases.

Description : Define thermochemistry?

Last Answer : “The branch of chemistry in which we study the heat changes during chemical reactions is called ThermoChemistry”.

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