how does energy affect
change?
 | Heat
and temperature are not the same thing. heat is the measure
of total energy transferred from one system to another; temperature
is the measure of average kinetic energy in a sample of matter. |
| The
specific heat capacity for a substance describes how much heat energy is
required to cause a temperature change. |
| Heat
of reaction: the energy released or absorbed during a chemical reaction or a
physical change – is measured in calorimeter. |
| The
amount of heat involved in a physical or chemical change can be expressed as
a ratio in stoichiomerty equations |
| Spontaneous change: a change that will occur because of the nature of the system, once it initiated. It goes all in one direction and will not go the other direction. Ex. Ice melts and once it does it won’t freeze unless it is put someplace really cool |
how do enthalpy and entropy drive and affect change?
| Enthalpy:
total energy content of a system. |
| Enthalpy
change: heat energy released or absorbed when a physical or chemical change
occurs at constant pressure. |
| When
heat is released during a change, enthalpy is decreased. Decreasing enthalpy
drives most chemical reactions |
| All
reactions require activation energy, which can be provided by adding energy
to the system or by converting the kinetic energy a substance already has. |
| Total
change in enthalpy can be calculated by adding together the enthalpy changes
for each part of a reaction. |
| Entropy:
a measure of the randomness or disorder of a system. |
| A
higher entropy level in a reaction results in a more stable product. |
| Entropy
and enthalpy values can be mathematically combined with temperature to
describe the free energy of a system and predict whether the reaction is
spontaneous. |
what are your energy needs?
| Resting
metabolic rate: energy expended by a person at rest in a thermally neutral
environment. |
| The thermic effect of food is the energy needed for the chemical reaction of digestion. |