Unit 6: Thermodynamics

Question 1

What does a rise of temperature indicate

Answer 1

exothermic reaction: release of energy from the system to surroundings, formation of bonds

Question 2

What does a decrease in temperature indicate

Answer 2

endothermic reaction: absorption of energy from the surroundings to the system, breaking of bonds

Question 3

What forces are used to determine relative associated energy

Answer 3

intermolecular or interparticle forces

Question 4

What are the characteristics of a heating curve with

Answer 4

increase from the y-axis with intermittent plateaus for solid melting and liquid boiling

Question 5

What are the characterisitics of a cooling curve

Answer 5

decrease from the y-axis with intermittent plateaus for gas condensing and liquid crystallizing

Question 6

What forces are overcome in solid melting

Answer 6

IPF

Question 7

What forces are overcome in liquid boiling

Answer 7

IMF

Question 8

What forces are remade in gas condensing

Answer 8

IMF

Question 9

What forces are remade in liquid crystallizing

Answer 9

IPF

Question 10

What is the relative associated kinetic energy in a warm body in relation to cooler body

Answer 10

higher

Question 11

What is the relative associated kinetic energy in a cool body in relation to a warmer body

Answer 11

less

Question 12

How do particles transfer energy between each other

Answer 12

collisions

Question 13

What is thermal equilibirum

Answer 13

when average kinetic energy of two bodies are the same (aka same temperature)

Question 14

What is the equation to determine heat transfer between two bodies

Answer 14

q=mc∆T

Question 15

What is the first law of thermodynamics

Answer 15

energy is conserved in chemical and physical processes

Question 16

Is the transfer of thermal energy in species with different masses and heat capacities expected to be the same or different

Answer 16

different

Question 17

How does heating a system effect its relative associated energy

Answer 17

it increases

Question 18

How does cooling a system effect its relative associated energy

Answer 18

it decreases

Question 19

How do chemical systems change their energy

Answer 19

heating/cooling
phase transitions
chemical reactions

Question 20

When does energy need to be transfered

Answer 20

melt
boil

Question 21

When does relative associated energy increase

Answer 21

solid-to-liquid
liquid-to-gas

Question 22

When does energy need to be released

Answer 22

freezes
condenses

Question 23

When does relative associate energy decrease

Answer 23

liquid-to-soild
gas-to-liquid

Question 24

What does a positive enthalpy value indicate

Answer 24

heat energy abosrbed

Question 25

What does a negative enthalpy value indicate

Answer 25

heat energy released

Question 26

How is potential energy of a system changed

Answer 26

breakage or formation of bonds

Question 27

What is used to determine the average energy required to break all of the reactants bonds

Answer 27

the sum of all bond energies in each reactant’s molecule

Question 28

What equation is used to determine the ∆H˚ of a reaction

Answer 28

∑∆H˚products- ∑∆H˚reactants