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प्रश्न
Answer the following in one or two sentences.
What is standard state of a substance?
उत्तर
- The standard state of a substance is the form in which the substance is most stable at a pressure of 1 bar and at a temperature of 298 K.
- If the reaction involves species in solution, its standard state is 1 M concentration.
e.g. Standard states of certain elements and compounds are (at 1 bar and 25 °C); \[\ce{H2_{(g)}, Hg_{(l)}, Na_{(s)}, C_{(graphite)}, C2H5OH_{(l)}, CaCO3_{(s)}, CO2_{(g)}, C2H5OH_{(l)}, H2O_{(l)}, CaCO3_{(s)}, CO2_{(g)}}\].
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संबंधित प्रश्न
Answer in brief.
How much heat is evolved when 12 g of CO reacts with NO2? The reaction is:
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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.
Calculate the standard enthalpy of combustion of CH4(g) if ΔfH°(CH4) = – 74.8 kJ mol–1, ΔfH°(CO2) = – 393.5 kJ mol–1 and ΔfH°(H2O) = – 285.8 kJ mol–1.
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- \[\ce{C_{(Graphite)} + O_{2(g)} -> CO_{2(g)}}\] ∆cH° = – 393 kJ mol–1
- \[\ce{H_{2(g)} + \frac{1}{2} O_{2(g)} -> H2O_{(l)}}\] ∆fH° = – 286 kJ mol–1
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Pressure, volume, mass, temperature.
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\[\ce{C6H6 + 7 1/2O2 -> 6CO2_{(g)} + 3H2O_{(l)}}\]; ΔH = −3264.6 kJ
Which of the following quantities of heat energy will be evolved when 39 g C6H6 are burnt?
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How much heat will be evolved in the formation of 60 g of CO2?
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Given that,
\[\ce{C_{(s)} + O_{2(g)} -> CO_{2(g)}}\] ΔH° = -X kJ
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C – H bond energy: 410.50 kJ mol−1
Enthalpy for the given reaction will be:
\[\begin{array}{cc}
\phantom{}\ce{H}\phantom{...}\ce{H}\phantom{...................}\ce{H}\phantom{...}\ce{H}\phantom{....}\\
\phantom{.}|\phantom{....}|\phantom{....................}|\phantom{....}|\phantom{.....}\\
\ce{C = C + H - H -> H - C - C - H}\\
\phantom{.}|\phantom{....}|\phantom{....................}|\phantom{....}|\phantom{.....}\\
\phantom{}\ce{H}\phantom{...}\ce{H}\phantom{...................}\ce{H}\phantom{...}\ce{H}\phantom{....}
\end{array}\]
Identify the invalid equation.
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