Answer
425.4k+ views
Hint:
The combustion and formation both are opposite processes. Combustion reaction is always exothermic i.e. heat of that reaction is negative then other one can be exothermic or endothermic i.e. heat of reaction can be negative or positive.
Complete step by step answer:
Heat of combustion and heat of formation are basically two kinds of heat of reaction. Heat of reaction is the energy which is released or absorbed during the reaction. This can be calculated from the change of energy between all reactants and all products.
The definition of heat of formation is, the amount of energy change due to the formation of 1 mole of a compound from its constituent elements.
The definition of heat of combustion is, the amount of heat or energy developed due to the total combustion of 1mole of a compound.
Now heat of the combustion reaction of glucose can be calculated on the basis of Hess’ law. Using formula,
\[\Delta H = \sum {\Delta {H_f}(product)} - \sum {\Delta {H_f}({\text{reactant}})} \]
The equation of combustion of graphite is,
\[C + {O_2}\xrightarrow{\Delta }C{O_2},\Delta H = - 395KJ/mole\] ……(1)
This reaction can also be considered as a formation reaction of \[C{O_{2.}}\]
The equation of combustion of \[{{\text{H}}_{\text{2}}}\] is,
\[H{}_2 + \dfrac{1}{2}O{}_2\xrightarrow{\Delta }H{}_2H = - 269KJ/MOLE\] ……(2)
This reaction can also be considered as a formation reaction of \[{H_2}O\]
The equation of formation of glucose is,
\[6C + 6{H_2} + 3{O_2} \to {C_6}{H_{12}}{O_6},\Delta H = - 1169{\text{ }}KJ/mole\] ……(3)
The equation of combustion of glucose is,
\[C{}_6H{}_{12}O{}_6 + 6O{}_2\xrightarrow{\Delta }6CO{}_2 + 6H{}_2O,\Delta H\]
Now according to the Hess’ law, the heat of reaction is,
\[
\Delta H = \sum {\Delta {H_f}(product)} - \sum {\Delta {H_f}({\text{reactant}})} \\
= \sum {6 \times \Delta {H_f}(C{O_2}) + 6 \times } \Delta {H_f}({H_2}O) - \sum {\Delta {H_f}({{\text{C}}_6}{H_{12}}{O_6})} + 6 \times \Delta {H_f}({O_2}) \\
= \sum {6 \times \left( { - 395} \right) + 6 \times } \left( { - 269} \right) - \sum { - 1169} + 0 \\
= \sum { - 2370 - } 1614 + 1169 \\
= - 2815KJ/mole \\
\]
The correct answer is A.
Note:
Remember the formula \[\Delta H = \sum {\Delta {H_f}(product)} - \sum {\Delta {H_f}({\text{reactant}})} \]. The molar heat of combustion is the amount of heat released when one mole of substance is completely burnt.
The combustion and formation both are opposite processes. Combustion reaction is always exothermic i.e. heat of that reaction is negative then other one can be exothermic or endothermic i.e. heat of reaction can be negative or positive.
Complete step by step answer:
Heat of combustion and heat of formation are basically two kinds of heat of reaction. Heat of reaction is the energy which is released or absorbed during the reaction. This can be calculated from the change of energy between all reactants and all products.
The definition of heat of formation is, the amount of energy change due to the formation of 1 mole of a compound from its constituent elements.
The definition of heat of combustion is, the amount of heat or energy developed due to the total combustion of 1mole of a compound.
Now heat of the combustion reaction of glucose can be calculated on the basis of Hess’ law. Using formula,
\[\Delta H = \sum {\Delta {H_f}(product)} - \sum {\Delta {H_f}({\text{reactant}})} \]
The equation of combustion of graphite is,
\[C + {O_2}\xrightarrow{\Delta }C{O_2},\Delta H = - 395KJ/mole\] ……(1)
This reaction can also be considered as a formation reaction of \[C{O_{2.}}\]
The equation of combustion of \[{{\text{H}}_{\text{2}}}\] is,
\[H{}_2 + \dfrac{1}{2}O{}_2\xrightarrow{\Delta }H{}_2H = - 269KJ/MOLE\] ……(2)
This reaction can also be considered as a formation reaction of \[{H_2}O\]
The equation of formation of glucose is,
\[6C + 6{H_2} + 3{O_2} \to {C_6}{H_{12}}{O_6},\Delta H = - 1169{\text{ }}KJ/mole\] ……(3)
The equation of combustion of glucose is,
\[C{}_6H{}_{12}O{}_6 + 6O{}_2\xrightarrow{\Delta }6CO{}_2 + 6H{}_2O,\Delta H\]
Now according to the Hess’ law, the heat of reaction is,
\[
\Delta H = \sum {\Delta {H_f}(product)} - \sum {\Delta {H_f}({\text{reactant}})} \\
= \sum {6 \times \Delta {H_f}(C{O_2}) + 6 \times } \Delta {H_f}({H_2}O) - \sum {\Delta {H_f}({{\text{C}}_6}{H_{12}}{O_6})} + 6 \times \Delta {H_f}({O_2}) \\
= \sum {6 \times \left( { - 395} \right) + 6 \times } \left( { - 269} \right) - \sum { - 1169} + 0 \\
= \sum { - 2370 - } 1614 + 1169 \\
= - 2815KJ/mole \\
\]
The correct answer is A.
Note:
Remember the formula \[\Delta H = \sum {\Delta {H_f}(product)} - \sum {\Delta {H_f}({\text{reactant}})} \]. The molar heat of combustion is the amount of heat released when one mole of substance is completely burnt.
Recently Updated Pages
How many sigma and pi bonds are present in HCequiv class 11 chemistry CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Why Are Noble Gases NonReactive class 11 chemistry CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Let X and Y be the sets of all positive divisors of class 11 maths CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Let x and y be 2 real numbers which satisfy the equations class 11 maths CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Let x 4log 2sqrt 9k 1 + 7 and y dfrac132log 2sqrt5 class 11 maths CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Let x22ax+b20 and x22bx+a20 be two equations Then the class 11 maths CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Trending doubts
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
At which age domestication of animals started A Neolithic class 11 social science CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Which are the Top 10 Largest Countries of the World?
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Give 10 examples for herbs , shrubs , climbers , creepers
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Difference Between Plant Cell and Animal Cell
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Write a letter to the principal requesting him to grant class 10 english CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Change the following sentences into negative and interrogative class 10 english CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Fill in the blanks A 1 lakh ten thousand B 1 million class 9 maths CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)