Question

ENERGY FROM CHEMICAL REACTIONS (page 8)

Many chemical reactions release energy, while others require energy to happen. These energy changes that occur during chemical reactions are due to changes in bonding between the reactant molecules and product molecules. Breaking bonds between atoms always requires energy, while creating bonds between atoms always releases energy.

Analyze each of the two chemical reactions below by calculating the total amount of energy needed to break the bonds in the reactants, the total amount of energy released upon bond formation in the products, and whether the reaction is exothermic or endothermic. Clearly explain your analysis in each case. Note that for help with this analysis, you should consult the Reaction Energy Tutorial in the Chapter 9 section of the Concept Review (Links to an external site.) page.

A. Combustion of methane CH₄ or natural gas:      CH₄ +   2 O₂    -->    CO₂   +   2 H₂O

B. Formation of hydrazine N₂H₄:      N₂ +   2 H₂    -->    N₂H₄

C. The top reaction (combustion of methane) is just one example of a general group of reactions known as combustion reactions. What is the general description of a combustion reaction? List some examples in society of how we take advantage of the energy released from such reactions.

Answer 1

Some examples of combustion reaction is

1) 2C_{​​​​​​2} H_{​​​​​​2} + 5 O_{​​​​​​2} = 4CO₂ + 2H₂ O

2) C_{​​​​​​3}​​​H_{​​​​4} + 4O₂ = 3CO₂ + 2H₂O

Burning of LPG is the good example of combustion reaction , we get heat for cooking purpose from LPG.

Burning of CNG is also a example of combustion reaction , use for car fuel.

2 combustion reaction: combustion reaction is that reaction where a hydrocarbon reacts with excess oxygen to produce carbondionide and water. - Actually combustion reaction is nothing but a type of burning reaction. The general chemical equation for combustion reaction of hydrocarbon is Cetty + (x + y)₂ = x co2+ H₂O. Advantages: 1) It provides energy quickly and moderately low cost (i) The amount of gas such as carbondionide, sulfur dionide nitrogendionide can be controlled and reduced by being resined further.