Which of the changes involve evolution of heat ?
Burning of fuels
Cooking of food
Digestion
Curdling
Answers
Answer:
The following changes involved evolution of heat:-
• BURNING OF FUELS
• COOKING OF FOOD
• DIGESTION OF FOOD
Explanation:
• Fuels release heat on burning:
Heat of combustion is total amount of heat released when a fuel is burnt when there is complete combustion with oxygen. It is a chemical reaction in which hydrocarbon is burnt and it roduces carbon dioxide, heat and water. The heat of combustion can be expressed as follows: energy/mole of fuel, energy/volume of the fuel.
roduces carbon dioxide, heat and water. The heat of combustion can be expressed as follows: energy/mole of fuel, energy/volume of the fuel.The carbon content in a fuel decides the amount of CO2 that will be produced from that fuel. This content is decided by carbon and hydrogen content in the fuel. When carbon and hydrogen combines with oxygen during combustion then heat is released. Methane which is a natural gas has higher energy content as compared to other fuels and has lower CO2 release level.
• Release of heat during cooking of food:-
Radiation heat transfer occurs when microwave (light waves) or infrared energy (heat waves) are spread into the food. As the microwaves penetrate the food, they bump into molecules of water and fat, causing them to vibrate rapidly. This vibration creates friction,hich creates heat that cooks the food.
• Release of heat during digestion:-
The digestion of food is a hydrolytic, exothermic, chemical reaction that in the digestive tract releases heat. The body tries to resist the increase in the central body temperature by instigating heat leakage to tHe atmospheric atmosphere and then passes the heat to the body and wants to raise the body temperature .When hot, by heat transfer to body tissues, the meal itself may want to increase the body temperature. However because the human body has a means to maintain its core temperature, by sweating and evaporation, convection currents, conduction and radiation, the heat gets lost to the external atmosphere. The temperature of the body may increase marginally, but under these conditions, it will remain within the natural range for a healthy body indefinitely.