Thermochemistry Chapter (Lecture 1) 9 Terms

Question 1

Internal Energy

Answer 1

A microscopic energy contains in a substance. Formula: Internal Energy (U)= Thermal Energy + Chemical Energy

Question 2

Thermal Energy

Answer 2

Energy that results in temperature.
TE= KE (Kinetic energy)
Ex: Higher T= Faster Molecular Motion

Question 3

Chemical Energy

Answer 3

Chem energy = Chem bonds
As chemical bonds break apart the chemical energy increases.
A physical change occurs (State of matter changes)

Question 4

Intermolecular attractions

Answer 4

Potential Energy that resides in Chemical energy

Question 5

System and Surrounding

Answer 5

Universe = System + Surrounding
System: Part of the universe chosen for Study
Surrounding: Part of the universe outside system

Question 6

What is system and surrounding connected by?

Answer 6

Matter: Flow of molecules across boundaries
Heat: Transfer of energy form high T to low T

Question 7

Work

Answer 7

Force acting through a distance

Question 8

Open systems

Answer 8

Systems that can exchange matter with surroundings like heat of work. Ex: Water vapor escaping from beaker

Question 9

Closed System

Answer 9

System does not allow flow of matter within surrounding. Ex: sealed flask or balloon with Helium. (Balloon expands; gas inside work on surrounding and surroundings lose energy
OR heat will flow of balloon if the outside temp is lower

Question 10

Isolated System

Answer 10

Cannot exchange any heat, work or matter with surrounding.

Question 11

Heat

Answer 11

(q) Internal Energy being transferred between a system and surrounding.
Heat flows from hot to cold Ta>Tb

Question 12

Calorie

Answer 12

Quantity of heat required to change temp of one gram of water by one-degree Celcius

Question 13

Conversion from Joule to Calorie

Answer 13

1 cal = 4.184 j

Question 14

Heat and law of Conservation of Energy

Answer 14

Heat gained by system = is lost by surroundings
Positive: Heat gained in system
Negative: Heat is lost in system
q system = - q surr

Question 15

Heat flows from surrounding to the system.

Answer 15

q system (+) q surr (-)

Question 16

Heat that flows from system to surrounding

Answer 16

q system (-) q surr (+)

Question 17

Heat Capacity

Answer 17

Capacity C = quantity of heat required to change the temperature of substance by 1 C
C= q/ Change in Temperature (J/ C)

Question 18

Extensive property

Answer 18

units: moles and grams
Ex: mass, volume, heat capacity (as more mass and volume is added they will increase)
Proportional to system size

Question 19

Intensive property

Answer 19

Does not depend on system size. Ex: Temp, Pressure, density

Question 20

Specific Heat Capacity (per gram)

Answer 20

Divided by system size to get intensive property
Formula: Csp = Heat supplied/(Temp rise) x (mass) = (q/change in Temp x grams) = (J/ C x g)

Question 21

Molar Heat Capacity (mer molar)

Answer 21

J/ C x mol

Question 22

Heat supplied

Answer 22

q= mCsp (change in Temperature)

Question 23

Specific heat values in metals

Answer 23

Some have different heat capacities such as Iron having 0.449 less than ICE with 2.11. Change in property can change specific heat values.

Question 24

Enthalpy Formula

Answer 24

H = U + PV

Question 25

Work formula

Answer 25

w= -P(Vf-Vi)

Question 26

Ef-Ei =

Answer 26

Qp x -P (Vf-Vi)

Question 27

Work being done by the system on surrounding

Answer 27

w<0

Question 28

Work being done by surrounding onto the system.

Answer 28

w>0