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The precise equivalence between calories and joules has varied over the years, but in thermochemistry and nutrition it is now generally assumed that one (small) calorie (thermochemical calorie) is equal to exactly 4.184 J, and therefore one kilocalorie (one large calorie) is 4184 J or 4.184 kJ.
Proteins and most carbohydrates have about 17 kJ/g (4 kcal/g), though there are differences between different kinds. For example, the values for glucose, sucrose, and starch are 15.57, 16.48 and 17.48 kilojoules per gram (3.72, 3.94 and 4.18 kcal/g) respectively.
Energy density is thus commonly expressed in metric units of cal/g, kcal/g, J/g, kJ/g, MJ/kg, cal/mL, kcal/mL, J/mL, or kJ/mL. Energy density measures the energy released when the food is metabolized by a healthy organism when it ingests the food (see food energy for calculation).
According to the FAO, the average minimum daily energy requirement is approximately 8,400 kilojoules (2,000 kcal) per adult and 4,200 kilojoules (1,000 kcal) a child. [3] This data is presented in kilojoules, as most countries today use the SI unit kilojoules as their primary measurement for food energy intake, [ 4 ] with the exception of the ...
1 cal / °C⋅g = 1 Cal / °C⋅kg = 1 kcal / °C⋅kg = 4184 J / kg⋅K [20] = 4.184 kJ / kg⋅K . Note that while cal is 1 ⁄ 1000 of a Cal or kcal, it is also per gram instead of kilo gram : ergo, in either unit, the specific heat capacity of water is approximately 1.
The difference between the two heating values depends on the chemical composition of the fuel. In the case of pure carbon or carbon monoxide, the two heating values are almost identical, the difference being the sensible heat content of carbon dioxide between 150 °C and 25 °C ( sensible heat exchange causes a change of temperature, while ...
The typical energy released as heat by a person at rest every 1/60 s (~ 16.6667 ms, basal metabolic rate); about 5,000 kJ (1,200 kcal) / day. The amount of electricity required to run a 1 W device for 1 s. The energy required to accelerate a 1 kg mass at 1 m/s 2 through a distance of 1 m.
The activation energy (E a) of a reaction is measured in kilojoules per mole (kJ/mol) or kilocalories per mole (kcal/mol). [2] Activation energy can be thought of as the magnitude of the potential barrier (sometimes called the energy barrier) separating minima of the potential energy surface pertaining to the initial and final thermodynamic ...