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# CHEM 116 EXAM 3

Question | Answer |
---|---|

1st Law of Thermodynamics | The energy of the universe is always constant |

2nd Law of Thermodynamics | The entropy of the universe is always increasing |

specific heat capacity | the amount of heat required to raise 1 gm of a substance by 1 degree Celsius or Kelvin |

If you add 2.05 J to 1g ice (0 deg. C), what will the final temperature value be? (C of ice = 2.05) | 0; because it takes a lot of energy to melt ice at a constant zero degree temperature |

In a graph of temperature versus heat, what is the slope of the graph equivalent to? | Specific heat capacity in that state |

state function | It's value depends only on the state of the system is in only not on the path it took to get there |

Hess's Law | since enthalpy(H) is a state function, then delta H of the reaction is the same regardless of the path or number of steps taken |

How do you determine delta H of the reaction? | Sum of delta H of the products - sum of delta H of the reactants |

standard enthalpies of formation | the enthalpy change for the formation of 1 mol of the substance from its elements in their standard states |

What is the delta H(f) for pure elements in standard states? | zero |

Boltzman equation | s=klog(W) |

3rd Law of Thermodynamics | S=0 at t=0K for a perfect crystal |

Is S always increasing or decreasing with temperature for a given substance | increasing |

3 main rules for estimating S | 1. larger moles have larger S 2. S gas > S liquid > S solid 3. For gas reactions: S is higher on the side with more moles of gas |

delta S of surroundings = | - (delta H)/T |

What is delta G | the maximum amount of energy available to do work |

delta G = | delta H - (t)(delta S) |

If G < 0 | the reaction is spontaneous from left to right |

If G > 0 | the reaction is not spontaneous from left to right |

What is the Sponanuity of a -H, +S, -G | product favored |

What is the Sponanuity of a -H, -S, ?G | Spontaneous at high temperatures |

What is the Sponanuity of a +H, +S, ?G | Spontaneous at low temperatures |

What is the Sponanuity of a +H, -S, +G | reactant favored |

On a graph of G versus Temp., what does the positive half of the graph represent? What does the negative half represent? | Positive: Not spontaneous Negative: Spontaneous |

When Q = K(eq), what does delta G equal | 0 |

if G > 0 what is K(eq) | K(eq)<1 |

if G < 0 what is K(eq) | K(eq)>1 |

Review calculations from 4/3 | |

What is a calorimeter | a device used to measure the heat released or absorbed by a physical or chemical process |

Units of standard molar entropy | J/molK |