Thermodynamics

Question 1

Ist Law of Thermodynamics

Answer 1

Energy can’t be created or destroyed, it can only be converted from one form to another

Question 2

Potential energy

Answer 2

stored within the bonds

Question 3

Kinetic energy

Answer 3

In the particles, they are always moving

Question 4

Specific heat capacity vs. heat capacity

Answer 4

Specific - heat needed to increase the temp of a unit mass of material by 1K (J/g degree C)

heat needed to increase the temp of an object by 1K (J/degree C)

Question 5

How does specific heat capacity differ from heat capacity

Answer 5

Specific heat of H20 is the same no matter the mass, heat capacity of pool is greater than a pot of water

Question 6

positive delta H (enthalpy)

Answer 6

endothermic

Question 7

negative delta H (enthalpy)

Answer 7

exothermic

Question 8

Ea

Answer 8

activation energy

Question 9

What is the amount of heat gained/lost based on

Answer 9

When the rxn is done - LA is used

Question 10

Combustion

Answer 10

Burning produces heat

CO2 + H2O (O2 in excess)
CO + H2O (O2 limited)

Question 11

Error in calorimetry

Answer 11

Some heat might be lost to the air or calorimeter, the measurements of the mass have fewer sig figs.

Question 12

deltaH^circle f

Answer 12

Enthalpy change associated with forming 1 mole of a cmpd from its elements in their standard states at standard conditions (298 K and 1 x 10^5 Pa)

Question 13

percent error

Answer 13

Accepted - actual / accepted x 100

Question 14

Hess’s Law

Answer 14

The enthalpy change for any chemical rxn is independent of the route, provided that starting conditions, final conditions, reactants and products are the same.

Question 15

Bond enthalpy

Answer 15

Energy needed to break 1 mole of bonds in gaseous molecules under standard conditions

Question 16

Why are bond enthalpies in the data booklet different?

Answer 16

They are averages, bond energy is different depending on the molecule.

Breaking 1st O-H bond in water is greater than the 2nd O-H bond

Question 17

How to calculate using bond enthalpies

Answer 17

Summation of bonds broken - summation of bonds formed.

Question 18

Entropy

Answer 18

delta S - Dispersal of matter

Question 19

Factors that increase entropy

Answer 19

1) change in state s–> l –> g-
2) Number of particles/dissociation
3) Number of moles of gas

Question 20

Equation for delta S of the rxn

Answer 20

Sum delta S products - sum delta S reactants

Question 21

Delta G

Answer 21

Gibbs Free Energy -
relates delta S, H and absolute temp (K)

Question 22

Equation for delta G

Answer 22

delta H - T(delta S)

Question 23

Delta G spontaneity

Answer 23

+ = not spontaneous
- = spontaneous