Thermodynamics
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New answer posted
3 months agoContributor-Level 10
This is a Short Answer Type Questions as classified in NCERT Exemplar
ΔrH? =ΣB.E (reactant)-ΣB.E (product)
=B.E.H2 + BEBR2 -2 *B.E>HBr
= 435+192-2 (*368)
= 109KJmol-1
New answer posted
3 months agoContributor-Level 10
43. A process which can take place of its own or initiate under some conditions. For example: Common salt dissolves in water of its own.
New answer posted
3 months agoContributor-Level 10
42. ?G = ?H – T?S
Where ?G = free energy change.
?H = enthalpy change.
?S = entropy change.
New answer posted
3 months agoContributor-Level 10
41. Amount of heat required to vapourize one mole of a liquid at constant temperature and under standard pressure (1bar) is called its standard enthalpy of vapourization or molar enthalpy of vapourization, ΔvapH?.
New answer posted
3 months agoContributor-Level 10
40. (i) First law of thermodynamics: It states that energy can neither be created nor be destroyed. The energy of an isolated system is constant.
?u = q + w
(ii) The standard enthalpy change for the formation of one mole of a compound from its elements in their most stable states of aggregation (also known as reference state is called Standard Molar Enthalpy of Formation. Its symbol is Δf H?, where the subscript ' f ' indicates that one mole of the compound in question has been formed in its standard state from its elements in their most stable states of aggregation.
New answer posted
3 months agoContributor-Level 10
39. In thermodynamics, a distinction is made between extensive properties and intensive properties. An extensive property is a property whose value depends on the
quantity or size of matter present in the system. For example, mass, volume, internal energy, enthalpy, heat capacity, etc. are extensive properties.
Those properties which do not depend on the quantity or size of matter present are known as intensive properties. For example, temperature, density, pressure etc. are intensive properties.
New answer posted
3 months agoContributor-Level 10
38. Since, there is an increase in the number of moles on the product side so, entropy increases and ?S is positive.
New answer posted
3 months agoContributor-Level 10
37. Hess law states that “If a reaction takes place in several steps then its standard reaction enthalpy is the sum of the standard enthalpies of the intermediate reactions into which the overall reaction may be divided at the same temperature.”
Or it can be stated as “The change of enthalpy of a reaction remains same whether the reaction is carried out in one step or several steps.”
&nbs
New answer posted
3 months agoContributor-Level 10
This is a Short Answer Type Questions as classified in NCERT Exemplar
Molar enthalpy change for graphite (ΔH)
= enthalpy change for 1 g x molar mass of C = -20.7*12 = -2.48 x 102 kJ mol-1
Since the sign of ΔH = -ve, it is an exothermic reaction.
New answer posted
3 months agoContributor-Level 10
This is a Short Answer Type Questions as classified in NCERT Exemplar
Given that, Cv = heat capacity at constant volume,
Cp = heat capacity at constant pressure
Difference between Cp and Cv is equal to gas constant (R).
.'. Cp – Cv = nR (where, n = no. of moles)
= 10 x 8.314 = 83.14J
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