The direction of heat flow is from a higher-temperature substance to a lower-temperature substance. Standard Units: Joules ( J ) or Calories ( c ) Calorie is defined as the amount of heat needed to raise the temperature of 1 gram of water by 1 Celsius degree. 4.18 joules = 1 calorie 1 calorie > 1 joule Definition of 1 calorie of heat energy: 1 calorie of heat energy is the energy required to raise the temperature of 1 gram of water by 1°C. Thermodynamics is the study of movement of particles due to application of heat to the particles. First Law of Thermodynamics: Whenever heat flows into or out of a system, the gain or loss of thermal energy equals the amount of heat transferred (energy is conserved); When thermal energy transfers as heat, it does so without net loss or gain. Second Law of Thermodynamics: Heat never spontaneously flows from a lower-temperature substance to a higher-temperature substance; heat can be made to flow the opposite wait only when work is done on the system by adding energy from another source. Third Law of Thermodynamics: No system can reach to absolute zero.
Check Yourself: Which will raise the temperature of water more - adding 4.19 joules or 1 calorie? 4.19 joules will raise the water temperature more because 1 calorie is 4.18, so there is a 0.01 joules difference. Entropy is a measure of the disorder of a system. Whenever energy freely transforms from one form to another, the direction of transformation is toward a state of greater disorder, therefore, toward one of greater entropy. The greater the disorder -> The higher the entropy . What is the entropy of 0°K? 0 Your room gets messier each week. In this case, the entropy of your room is increasing . Specific Heat Capacity is defined as the quantity of heat required to change the temperature of 1 unit mass of a substance by 1°C. It determines the rate(speed) with which they become hot or cold while interacting with the surrounding. ● Thermal inertia that indicates the resistance of a substance to a change in temperature. ● Sometimes called specific heat . To say the water has a high specific heat capacity is to say the water requires a lot of energy in order to increase in temperature , gives off a lot of energy in cooling , and has a lot of “thermal inertia” . Specific Heat Capacity measures the hesitant of an object to change its temperature (thermal inertia). Which has the higher specific heat, water or land? Water has the higher specific heat. Thermal expansion ● When the temperature of a substance is increased, its particles jiggle faster and move farther apart. ● All forms of matter generally expand when heated and contract when cooled. When stringing telephone lines between the poles in the summer, it is advisable to allow the lines to sag . Expansion of Water When water becomes ice, it expands. Ice has open-structured crystals resulting from strong bonds at certain angles that increase its volume. This makes ice less dense than water.
- Spring '14