Question | Answer |
When a reaction is exothermic, energy will be thought of as a _______ in the reaction. | Product |
When a reaction is endothermic, energy will be thought of as a ________. | Reactant |
Potential energy= | Energy stored in chemical bonds of a substance |
Kinetic energy= | Energy that is released or absorbed |
Change in Enthalpy (⌂H) | The energy change that accompanies a chemical reaction |
1 calorie= | 4.184 Joules |
⌂H is _______ for endothermic reactions | Positive |
⌂H is _______ for exothermic reactions | Negative |
⌂H= | Energy required to break bonds - Energy released when bonds form |
Hess's Law | Enthalpy is state function and is therefore independent of path. |
State function | Any quantity that depends solely on the final destination, not the way you get to that destination. |
Enthalpy of formation (⌂Hf) | The ⌂H of a formation reaction |
Standard conditions | 25 C, 1.00 atm |
⌂H^0= | Σ⌂Hf^0 (products) - Σ⌂Hf^0 (reactants) |
The standard enthalpy of formation of an element in its elemental form is _____ | zero |
Hess's Law is more accurate because it | also takes into account the phase of the substance involved |
Activation energy | The energy necessary to start a chemical reaction |
Entropy | A measure of the disorder that exists in any system |
The Second Law of Thermodynamics | The entropy of the universe must always either increase or remain the same. It can never decrease |
The ______ state has the least amount of entropy associated with it. | solid |
The entropy of the ______ state is higher than the solid state. | liquid |
The entropy of the ______ state is the highest of all | gaseous |
The entropy of a system ______ with increasing temperature | increases |
The entropy of a system _____ as the matter it contains increases | increases |
⌂Suniverse | ≥0 |
⌂S^0= | ΣS^0 (products) - ΣS^0 (reactants) |
All substances, even elements, have an _______ _______ | absolute entropy |
⌂G= | ⌂H - T × ⌂S |
When ⌂G < 0, then reaction is _________ with the Second Law and is thus _________ | consistent, spontaneous |
⌂G > 0, then the reaction ______ proceed, because it ______ the Second Law | cannot, violates |
If the reaction is ______ and ⌂S is ______, then reaction will never occur. | endothermic, negative |
If the reaction is _____ and ⌂S is _____, the reaction will always be spontaneous. | exothermic, positive |
⌂G^0= | Σ⌂Gf^0 (products) - Σ⌂Gf^0 (reactants) |