What is the heat required to increase the temperature of 1 gram of water by 1 degree Celsius called?

The heat required to increase the temperature of 1 gram of water by 1 degree Celsius is known as a calorie. This unit of measurement is specifically defined in the context of thermodynamics and is a fundamental concept in understanding heat energy transfer in various scientific disciplines, particularly in chemistry and nutrition.

The calorie is commonly used in food science to quantify the amount of energy that food provides when consumed. It serves as a clear and practical way to express energy in the context of metabolic processes.

In contrast, a joule is the SI unit of energy and is often used in various scientific calculations. A kilocalorie, also known as a large calorie, is equal to 1,000 small calories and is used to express food energy, but it relates to 1,000 grams of water instead of 1 gram. The British thermal unit (BTU) measures heat energy as well, but it is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit, which further distinguishes it from the calorie.

Thus, the definition of a calorie directly aligns with the specific requirement of the question regarding the heat needed to raise 1 gram of water by 1 degree Celsius.