Advertisements
Advertisements
प्रश्न
Calculate the standard enthalpy of:
\[\ce{N2H_{4(g)} + H_{2(g)} -> 2NH_{3(g)}}\]
If ΔH0(N – H) = 389 kJ mol–1, ΔH0(H – H) = 435 kJ mol–1, ΔH0(N – N) = 159 kJ mol–1.
Advertisements
उत्तर
\[\begin{array}{cc}
\phantom{}\ce{H}\phantom{...}\ce{H}\phantom{......................}\ce{H}\phantom{.....}\\
\phantom{}|\phantom{....}|\phantom{.......................}|\phantom{.....}\\
\phantom{}\ce{N - N(g) + H - H(g) -> 2N - H}\\
\phantom{}|\phantom{....}|\phantom{.......................}|\phantom{.....}\\
\phantom{}\ce{H}\phantom{...}\ce{H}\phantom{......................}\ce{H}\phantom{.....}
\end{array}\]
ΔrH0 = ∑ΔH0(reactant) – ∑ΔH0(product)
= [4ΔH0(N – H) + ΔH0(N – N) + ΔH0(H – H)] – [6ΔH0(N - H)]
= ΔH0(N – N) + ΔH0(H – H) – 2ΔH0(N – H)
= 1 × 159 + 1 mol × 435 – 2 × 389
= – 184 kJ
APPEARS IN
संबंधित प्रश्न
Answer in brief.
How will you calculate reaction enthalpy from data on bond enthalpies?
Answer in brief.
What is the standard enthalpy of combustion? Give an example.
Calculate the total heat required
a) to melt 180 g of ice at 0 °C
b) heat it to 100 °C and then
c) vapourise it at that temperature.
[Given: ΔfusH° (ice) = 6.01 kJ mol-1 at 0 °C, ΔvapH° (H2O) = 40.7 kJ mol-1 at 100 °C, Specific heat of water is 4.18 J g-1 K-1]
The enthalpy change for the reaction, \[\ce{C2H4_{(g)} + H2_{(g)} -> C2H6_{(g)}}\] is −620 J when 100 mL of ethylene and 100 ml of \[\ce{H2}\] react at 1 bar pressure. Calculate the pressure volume type of work and ΔU for the reaction.
The standard enthalpy of formation of water is - 286 kJ mol-1. Calculate the enthalpy change for the formation of 0.018 kg of water.
Calculate enthalpy of formation of HCl if bond enthalpies of H2, Cl2 and HCl are 434 kJ mol-1, 242 kJ mol–1 and 431 kJ mol–1 respectively.
Define the Standard enthalpy of combustion.
State and explain Hess’s law of constant heat summation.
The enthalpy change of the following reaction:
\[\ce{CH_{4(g)} + Cl_{2(g)} -> CH3Cl_{(g)} + HCl_{(g)}ΔH^0 = –104 kJ}\]
Calculate C – Cl bond enthalpy. The bond enthalpies are:
| Bond | C − H | Cl − Cl | H − Cl |
| ∆H°/kJ mol−1 | 414 | 243 | 431 |
Define standard enthalpy of formation.
When 2 moles of C2H6(g) are completely burnt, 3129 kJ of heat is liberated. If ∆Hf for CO2(g) and H2O(l) are −395 and −286 kJ per mole respectively, the heat combustion of C2H6(g) is ____________.
The heat of formations of CO(g) and CO2(g) are −26.4 kcal and −94.0 kcal respectively. The heat of combustion of carbon monoxide will be ____________.
The enthalpy change accompanying a reaction in which 1 mole of the substance in the standard state reacts completely with oxygen or is completely burnt is called as ____________.
lf, \[\ce{C_{(s)} + O2_{(g)} -> CO2_{(g)}}\], ∆H = x .........(i)
\[\ce{CO_{(g)} + 1/2O2_{(g)} -> CO2_{(g)}}\], ∆H = y .......(ii)
Then, the heat of formation of CO is:
\[\ce{S + 3/2O2 -> SO3 +2{x} kcal}\] .........(i)
\[\ce{SO2 + 1/2O2 -> SO3 + {y} kcal}\] .......(ii)
The heat of formation of SO2 is ____________.
The enthalpy of formation of nitrogen dioxide is +33.2 kJ mol−1. The enthalpy of the reaction \[\ce{2N2_{(g)} + 4O2_{(g)} -> 4NO2_{(g)}}\]; is ____________.
Standard enthalpy of formation of water is - 286 kJ mol-1. When 1800 mg of water is formed from its constituent elements in their standard states the amount of energy liberated is ______.
Given that,
\[\ce{C_{(s)} + O_{2(g)} -> CO_{2(g)}}\] ΔH° = -X kJ
\[\ce{2CO_{(g)} + O_{2(g)} -> 2CO_{2(g)}}\] ΔH° = - Y kJ, then standard enthalpy of formation of carbon monoxide is ________.
Which of the following equations has ΔfH° and ΔH° same?
How many moles of helium gas occupies 22.4 Lat 0°c and at 1 atmospheric pressure?
When the enthalpy of combustion of carbon to carbon dioxide is - 360 kJ mol-1, then the enthalpy change for the formation of 18 g of CO2 from carbon and dioxygen at the same temperature in kJ will be ______.
The enthalpy change that accompanies a reaction in which 1 mole of its standard state is formed from its elements in their standard states
Standard enthalpy of combustion of a substance is given. Then Write thermochemical equation.
ΔcH0[C2H5OH(1)] = - 1409 kJ mol-1
Standard enthalpy of combustion of a substance is given. Then Write thermochemical equation.
ΔcH0[CH3CHO(l)] = - 1166 kJ mol-1
For the reaction, aA + bB → cC + dD, write the expression for enthalpy change of reaction in terms of enthalpies of formation of reactants and products.
Draw energy profile diagram and show:
- activated complex
- energy of activation for forward and backward reactions
- enthalpy of reaction
