[1][3] the small calorie or gram calorie was defined as the amount of heat needed to cause the same increase in one gram of water. it is generally used in publications and package labels to express the energy value of foods in per serving or per weight, recommended dietary caloric intake,[6][7] metabolic rates, etc. [2] this usage was adopted by wilbur olin atwater, a professor at wesleyan university, in 1887, in an influential article on the energy content of food. [16] the small calorie was originally part of the metric system (si),[10] but it was officially deprecated by the ninth general conference on weights and measures in 1948.
the two definitions most common in older literature appear to be the 15 °c calorie and the thermochemical calorie. in the majority of other countries, nutritionists prefer the kilojoule to the kilocalorie. it is mostly used to express the amount of energy released in a chemical reaction or phase change, typically per mole of substance, as in kilocalories per mole. [32] it is also occasionally used to specify other energy quantities that relate to reaction energy, such as enthalpy of formation and the size of activation barriers.
the calorie was originally defined as the amount of heat required at a pressure of 1 standard atmosphere to raise the temperature of 1 gram of water 1° celsius. since 1925 this calorie has been defined in terms of the joule, the definition since 1948 being that one calorie is equal to approximately 4.2 joules. other less common definitions in this series are the 20° calorie (4.18190 joules) from 19.5° to 20.5° c; and the mean calorie (4.19002 joules) defined as 1/100 of the heat necessary to raise the temperature of 1 gram of water from 0° to 100° c. another calorie, a unit of heat energy, is the international table calorie (it calorie), originally defined as 1/860 international watt-hour.
a unit of heat energy used in thermochemistry is the thermochemical calorie, equal to 4.184 joules. it is commonly used as the unit for heat capacities, latent heats, and heats of reaction. thus, the “calories” counted for dietary reasons are in fact kilocalories, with the “kilo-” prefix omitted; in scientific notations a capitalized calorie is used. in nutrition it has been proposed that the kilojoule replace the kilocalorie as the unit of choice for discussing the energy value of foods.
the small calorie or gram calorie was defined as the amount of heat needed to cause the same increase in one gram of water. thus, 1 large calorie is equal to the calorie was originally defined as the amount of heat required at a pressure of 1 standard atmosphere to raise the temperature of 1 gram of water 1° celsius. one calorie (kcal) equals 4.18 kj or 4,184 joules (j) ( 1trusted source ). to convert from calories to kj, multiple calories by 4.18. conversely, kcal to calories, kcal to calories, kilocalorie, definition of calories in food, calorie definition chemistry.
one calorie is defined as the amount of heat required to raise the temperature of one gram of water through one degree celsius. the “calorie” we refer to in food is actually kilocalorie. one (1) kilocalorie is the same as one (1) calorie (uppercase c). a kilocalorie is the amount of the capitalized calorie as used to indicate 1 kcal on u.s. food labels derives from atwater’s 1887 article on food energy in century a calorie is a unit of energy. counting calories is one way to monitor weight loss., how many kcal per day, calorie deficit, kcal to calories burned, 30 kcal to calories.
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