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Chemistry Ch. 5
Thermochemistry
| Term | Definition |
|---|---|
| System | A specific amount of matter that is being studied |
| Surroundings | Everything outside of the system |
| Open system | A system that can transfer energy and matter to its surroundings |
| Closed system | A system that can transfer energy, but not matter, to its surroundings |
| Isolated system | A system that does not transfer energy or matter to its surroundings |
| Work | The energy required to move and object over some distance |
| Equation for work | w = (F)(d) |
| Force due to gravity | F = (m)(g) |
| Gravitational potential energy | w = (m)(g)(h) |
| State function | The value depends only on the present state of the system, not the path it took to get there |
| Endothermic | Heat flows into the system from its surroundings (+ΔE)(+ΔH) |
| Exothermic | Heat flows from the system into its surroundings (-ΔE)(-ΔH) |
| Internal energy (E) | The sum of all kinetic and potential energies of the components of the system |
| ΔE | Change in internal energy = (initial E) - (final E) |
| Relating ΔE to heat and work | ΔE = q + w |
| Enthalpy (H) | A thermodynamic function used to account for the heat flow during a constant pressure process |
| Equation for enthalpy | H = E + PV |
| Pressure-volume work | Work performed by expansion of a gas against a resisting pressure |
| P-V work when pressure is constant | w = –P ΔV |
| Calorimeter | A device used to measure heat flow |
| Heat capacity (C) | The amount of heat required to raise the temperature of a sample of matter by 1 K |
| Molar heat capacity (Cm) | The amount of heat required to raise the temperature of one mole of a substance by 1 K |
| Specific heat (Cs) | The amount of heat required to raise the temperature of one gram of a substance by 1 K |
| Equation for specific heat | Cs = (q)/(mΔT) |
| Equation for heat gain or loss | q = m x Cs x ΔT |
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jabflat