# Energy All chemical reactions involve changes in energy as well as [[matter]]. There are many other useful forms of energy that are available through chemical reactions other than combustion ## Units of Energy calories (c) joules (J) work (w) - Temperature: The measurement of heat in matter - Heat: The speed of particles --- > [!info] Heat Capacity > $ q = m \cdot C \cdot \Delta T $ > > $m$ = Mass > $C$ = Heat Capacity > $\Delta T$ = Change in Temperature $ q_{reaction} + q_{solution} = 0 $ $ -q_A = q_B $ ## Enthalpy - **state function:** a property of a system that depends only on the state of the system - **path function:** a property of a system that depends on the path by the system achieved a particular state $\Delta H$ = Change in Enthalpy ## Entropy [[Entropy]] ## Spontaneity > [!info] General Definition of "Spontaneous" > **spon·ta·ne·ous** *adj.*: performed or occurring as a result of a sudden inner impulse or inclination and without premeditation or external stimulus. A **spontaneous process** occurs under a given set of conditions. - A spontaneous reaction doesn't necessarily mean an instantaneous reaction. - Spontaneous processes occur in order to decrease the energy of a system A **nonspontaneous process** will not take place unless it is driven by the continual input of energy from an external source. > The **spontaneity** *(spon·ta·ne·i·ty)* of a process is ***not*** correlated to its speed. ## Free Energy ### ### Free Energy and Chemical Equilibrium > [[Chemical Equilibria]] During the course of a chemical reaction, not all the reactants and products will be at their standard states. Under this condition, the relationship between $\Delta G$ and $\Delta G \degree$, which can be derived from $\Delta G = \Delta G \degree + RT \cdot ln(Q)$ - $R$ is the gas constant ($8.314 \frac{J}{K \cdot mol}$) - $T$ is the absolute temperature (K) - $Q$ is the reaction quotient --- > [!question]+ Practice: Calculating an Equilibrium Constant using Standard Free Energy > a > > > > [!check]- > > the answer is: