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प्रश्न
The enthalpies of all elements in their standard states are ______.
पर्याय
unity
zero
< 0
different for each element
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उत्तर
The enthalpy of all elements in their standard state is zero.
संबंधित प्रश्न
The reaction of cyanamide, NH2CN(s), with dioxygen was carried out in a bomb calorimeter, and ΔU was found to be −742.7 kJ mol−1 at 298 K. Calculate enthalpy change for the reaction at 298 K.
\[\ce{NH_2 CN(g) + 3/2 O_2(g) -> N_2(g) + CO_2(g) + H_2O(l)}\]
Calculate the enthalpy change on freezing of 1.0 mol of water at 10.0°C to ice at - 10.0°C. ΔfusH = 6.03 kJ mol-1 at 0°C.
Cp[H2O(l)] = 75.3 J mol-1 K-1
Cp[H2O(s)] = 36.8 J mol-1 K-1
Enthalpy of combustion of carbon to CO2 is –393.5 kJ mol–1. Calculate the heat released upon formation of 35.2 g of CO2 from carbon and dioxygen gas.
Enthalpies of formation of CO(g), CO2(g), N2O(g) and N2O4(g) are -110 kJ mol-1, - 393 kJ mol-1, 81 kJ mol-1 and 9.7 kJ mol-1 respectively. Find the value of ΔrH for the reaction:
\[\ce{N2O_{4(g)} + 3CO_{(g)} → N2O_{(g)} + 3CO_{2(g)}}\]
Given
\[\ce{N_{2(g)} + 3H_{2(g)} -> 2NH_{3(g)}}\]; ΔrHθ = –92.4 kJ mol–1
What is the standard enthalpy of formation of NH3 gas?
Calculate the standard enthalpy of formation of CH3OH(l) from the following data:
\[\ce{CH3OH_{(l)} + 3/2 O2_{(g)} →CO_{2(g)} + 2H2O_{(l)}}\] ; ΔrHθ = –726 kJ mol–1
\[\ce{C_{(g)} + O_{2(g)} →CO_{2(g)}}\] ; ΔcHθ = –393 kJ mol–1
\[\ce{H_{2(g)} +1/2 O_{2(g)} → H2O_{(l)}}\] ; ΔfHθ = –286 kJ mol–1.
Calculate the entropy change in surroundings when 1.00 mol of H2O(l) is formed under standard conditions. ΔfHθ = –286 kJ mol–1.
The value of ∆fHΘ for \[\ce{NH3}\] is – 91.8 kJ mol–1. Calculate enthalpy change for the following reaction:
\[\ce{2NH3(g) -> N2(g) + 3H2(g)}\]
For a reaction, A `→` B, enthalpy of reaction is −4.2 kJ mol−1 and enthalpy of activation is 9.6 kJ mol−1. The correct potential energy profile for the reaction is shown in option.
For a reaction, A `→` B, the enthalpy of reaction is −4.2 kJ mol−1 and the enthalpy of activation is 9.6 kJ mol−1. The correct potential energy profile for the reaction is shown in the option.
