Vocabulary 1
What is heat?
The energy passed from a warmer to a cooler object
What is enthalpy?
The total estimated energy content of a sample
What is entropy?
The randomness or disorder of a system
What is the equation for heat or enthalpy change?
q = mCAT
What is temperature?
The measure of the average kinetic energy of particles
What is an exothermic reaction?
When a reaction releases energy into its surroundings
What is Hess's Law?
The overall enthalpy change for a reaction is equal to the sum of the enthalpy changes for the individual steps in the process
What is something you can see in a reaction equation that shows you that the reaction increased the entropy of the system?
Larger number of product moles
More different types of product compounds
More gases and liquids in products than in reactants
Which equation helps you determine whether a reaction is spontaneous or not?
AG = AH - TAS
What is thermodynamics?
the branch of science concerned with energy changes
What is specific heat capacity?
The energy as heat needed to raise the temperature of 1 gram of a substance by 1 K
What is bomb calorimetry?
The experimental measure of an enthalpy change for a combustion reaction using a sturdy steel device
What is something you can do to a reaction that will increase its entropy?
Decrease the pressure
Increase the temperature
Increase the dispersal or diffusion
Increase the volume
How much heat does it take to increase the temperature of 55 grams of iron by 20.o C? The specific heat capacity of iron is 0.422 J/goC.
460 J
What is Gibb's Free Energy?
The free energy available to do work in a system
What is an intensive property?
A property that is not dependent on the size of a sample
What is adiabatic calorimetry?
The experimental measure of an enthalpy change for an aqueous reaction using an insulating container
If a reaction has a positive entropy and a negative enthalpy, will it be spontaneous?
Always
Given the standard enthalpy of formation for the following compounds, calculate the change in enthalpy of the reaction 2Ag + BaCl2 → 2AgCl + Ba
BaCl2 AHf = -860.1 kJ/mol
AgCl AHf = -127.0 kJ/mol
AH = 606.1 kJ/mol
What is a spontaneous reaction?
A reaction that can occur without any outside help, like an input of energy
What is an extensive property?
A property is that dependent on the size of a sample
Which has more heat: a lake at 275 K or a cup of water at 300 K
The lake at 90 K
If a reaction has a negative enthalpy and a negative entropy, will it be spontaneous?
Only at low temperatures
Calculate AH for this reaction using Hess's Law:
Final: 4NH3 + 5O2 → 4NO + 6H2O
Step 1: N2 + O2 → 2NO AH = -180.5 kJ
Step 2: N2 + 3H2 → 2NH3 AH = -91.8 kJ
Step 3: 2H2 + O2 → 2H2O AH = -483.6 kJ
AH = -1628.2 kJ
What is standard thermodynamic temperature?
25.00o C or 298.15 K