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प्रश्न
Select the most appropriate option.
The enthalpy of formation for all elements in their standard states is _______.
विकल्प
unity
zero
less than zero
different elements
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उत्तर
The enthalpy of formation for all elements in their standard states is zero.
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संबंधित प्रश्न
Select the most appropriate option.
Bond enthalpies of H–H, Cl–Cl, and H–Cl bonds are 434 kJ mol–1, 242 kJ mol–1, and 431 kJ mol–1, respectively. Enthalpy of formation of HCl is _______.
Answer in brief.
Obtain the expression for work done in chemical reaction.
Obtain the relationship between ΔH and ΔU for gas phase reactions.
Calculate the amount of work done in the
1) Oxidation of 1 mole HCl(g) at 200 °C according to reaction.
4HCl(g) + O2(g) → 2Cl2(g) + 2H2O(g)
2) Decomposition of one mole of NO at 300 °C for the reaction
2NO(g) → N2(g) + O2(g)
Answer the following question.
When 6.0 g of O2 reacts with CIF as per
\[\ce{2ClF_{(g)} + O2_{(g)} -> Cl2O_{(g)} + OF2_{(g)}}\]
The enthalpy change is 38.55 kJ. What is the standard enthalpy of the reaction? (Δr H° = 205.6 kJ)
Calculate the standard enthalpy of formation of \[\ce{CH3OH_{(l)}}\] from the following data:
\[\ce{CH3OH_{(l)} + 3/2 O2_{(g)} -> CO2_{(g)} + 2H2O_{(l)} }\]; ΔrH° = − 726 kJ mol-1
\[\ce{C_{(graphite)} + O2_{(g)} -> CO2_{(g)}}\]; ΔcH° = −393 kJ mol−1
\[\ce{H2_{(g)} + 1/2 O_{(g)} -> H2O_{(l)}}\]; ΔfH° = −286 kJ mol−1
Write the mathematical relation between ΔH and ΔU during the formation of one mole of CO2 under standard conditions.
Enthalpy of neutralization is always a constant when a strong acid is neutralized by a strong base: account for the statement.
Calculate the enthalpy change for the reaction \[\ce{Fe2O3 + 3CO -> 2Fe + 3CO2}\] from the following data.
\[\ce{2Fe + 3/2O2 -> Fe2O3}\]; ΔH = −741 kJ
\[\ce{C + 1/2O2 -> CO}\]; ΔH = −137 kJ
\[\ce{C + O2-> CO2}\]; ΔH = −394.5 kJ
For which of the following ∆U = ∆H?
The difference between heats of reaction at constant pressure and at constanl volume for the reaction
\[\ce{2C6H6_{(l)} + 15O2_{(g)} -> 12CO2_{(g)} + 6H2O_{(l)}}\] at 25°C in kJ
When 6.0 g of O2 reacts with CIF as per \[\ce{2ClF_{(g)} + O2_{(g)} -> Cl2O_{(g)} + OF2_{(g)}}\] the enthalpy change is 38.55 kJ. The standard enthalpy of the reaction is ____________.
Identify the equation in which change in enthalpy is equal to change in internal energy.
The enthalpy change for two reactions are given by the equations
\[\ce{2Cr_{(s)} + 1.5 O2_{(g)} -> Cr2O3_{(s)}}\];
∆H1 = −1130 kJ ............(i)
\[\ce{C_{(s)} + 0.5 O2_{(g)} -> CO_{(g)}}\];
∆H2 = −110 kJ .........(ii)
What is the enthalpy change, in kJ, for the following reaction?
\[\ce{3C_{(s)} + Cr2O3_{(s)} -> 2Cr_{(s)} + 3CO_{(g)}}\]
For the reaction, \[\ce{A_{(s)} + 2B_{(g)} -> 5C_{(s)} + D_{(l)}}\], ∆H and ∆U are related as ____________.
If 2 kJ of heat is released from system and 6 kJ of work is done on the system, what is enthalpy change of system?
In which of the following reactions, ΔH is not equal to ΔU?
What is the amount of work done when 0.5 mole of methane, CH4 (g), is subjected to combustion at 300 K? (Given, R = 8.314 JK-1mol-1)
Calculate ΔU if 2 kJ heat is released and 10 kJ of work is done on the system.
Under what conditions ΔH = ΔU?
Calculate the work done in oxidation of so2(g) at 25°C if, \[\ce{2SO_{2(g)} + O2_{(g)} -> 2SO_{3(g)}}\], R = 8.314 J K−1 mol−1.
In a particular reaction, 2 kJ of heat is released by the system and 8 kJ of work is done on the system. Determine ΔU.
Calculate work done in oxidation of 4 moles of SO2 at 25°C. (Given: R = 8.314 JK−1 mol−1 ).
Define enthalpy.
