10.1 Energy - 10.2 Heat Capacity Flashcards
Energy
The capacity to do work or supply heat
chemical potential energy
energy stored in chemicals because of their compositions
The atoms and their arrangements in a substance determine the amount of energy stored in the substance.
Heat
represented by q is a form of energy that always flows from warmer object to it cooler object
Law of conservation of energy
states that in any chemical or physical process, energy is neither created nor destroyed.
In electrical appliances, some energy is wasted as heat; All of the energy involved in a process can be accounted for as work, stored (potential) energy, or heat.
Thermochemistry
is the study of heat changes that occur during chemical reactions and physical changes of state.
All chemical reactions and changes in the physical state of a substance involve the release or absorption of heat.
calorie
the amount of heat required to raise 1 g of pure water by 1 degree Celsius, (cal)
kcal (Cal or Calorie) raises 1 kg of H2O by 1 degree Celsius (=1000 cal)
The kcal is the dietary Calorie
41 Calories of something burns to produce 41 kilocalories.
joule
the SI unit of heat and energy, one kcal = 4186 joules (or 1 kilojoule) and one cal = 4.2 joules, 1 joule will raise the temperature of 1 g H2O 0.239 degrees C.
1 Calorie = 1000 cal = 1 kcal = 4186 J, 1 J = 0.239 cal
heat capacity
the amount of heat it takes to change an object’s temperature by exactly 1 degree C
as the mass of an object increases, so does its heat capacity, and heat capacity also depends on the chemical composition. (1 pound of rubber will have a different capacity than 1 pound of metal.)
specific heat capacity
the specific heat, represented by C, of a substance is the amount of heat it takes to raise the temperature of 1 gram of the substance 1 degree Celsius. It is measured in J/(g x °C) or cal/(g x °C).
water has the highest specific heat (4.18 j/g°C or 1 cal/g°C), metals have low specific heats.
