multiplied by distance. It can also be described as mass multiplied by acceleration multiplied by distance (as force is mass multiplied by acceleration). Heat, on the other hand, is thermal energy or energy that can go from one object to another. This net transfer of heat only stops when the two objects arrive at the same temperature. Any form of energy can be described along the same lines as kinetic energy because forms of energy can be interconverted. The SI unit of energy is called the joule or J. One joule is a kilogram meter squared per second squared. Most scientists use kilojoules as a joule is such a small form of energy. Your takeaway from this is that all forms of energy can be expressed this way. A common non-SI unit of energy is called the calorie which is the amount of energy needed to raise the temperature of a gram of water from 14.5 degrees Celsius to 15.5 degrees Celsius. The different temperatures are used because the amount of energy required to do this actually varies according to the elevation. Since a calorie is a small quantity, the term kilocalorie is used, which is what is described when looking at the socalled “calories” in food items. Another way to describe a calorie is in terms of the number of joules it involves: 1 calorie is equal to exactly 4.184 Joules.
PROPERTIES OF HEAT IN CHEMISTRY Heat or thermal energy will flow from one place to another in a system. The reaction of chemical substances is referred to as the system, while there can also be heat energy involved with the surroundings, the container the reaction is taking place in, and even the rest of the universe. Heat energy doesn’t always stay within the system but can transfer to the surroundings. You need to understand that there are three different systems seen in chemistry. An open system can exchange matter and energy with the surroundings, such as is seen when water boils in a pan. The reaction of water liquid going to water vapor does not stay in the system but goes into the environment. In a closed system, energy is exchanged between types of matter but not with the surroundings. Isolated systems exchange no matter and no energy with the surroundings. There is practically no system that is truly isolated. The amount of energy lost in a reaction is the same as the amount
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