Chapter 5 Thermochemistry

Question 1

Thermodynamics

Answer 1

Study energy and its transformations

Question 2

Sytem

Answer 2

part of the universe of interest (reaction vessel)

Question 3

Surroundings

Answer 3

rest of the universe

Question 4

3 Types of Systems

Answer 4

Open, Closed, and Isolated

Question 5

Open System

Answer 5

Mass, heat, energy can be exchanged

Question 6

Closed System

Answer 6

No mass exchanged-only heat, energy, and work

Question 7

Isolated System

Answer 7

No mass, heat, or work can be exchanged (ex: universe)

Question 8

Where does the exchange take place?

Answer 8

At boundary btw system and surrounding during a change in state

Question 9

State

Answer 9

Condition in which all variables are fixed and unvarying

Question 10

When does a system change its state?

Answer 10

When one or more of these variables are changed (Temp, Gas at V1, P1, T1–>Gas at V2, P2, T2, Phase change-solid to gas/gas to solid

Question 11

Isothermal Change

Answer 11

Change at constant temp (supply or take away heat to maintain temp)

Question 12

Abiabatic Change

Answer 12

No heat exchanged during change-system is insulated from surroundings

Question 13

Isobaric Change

Answer 13

One at constant pressure

Question 14

What are normal laboratory conditions?

Answer 14

Isothermal and Isobaric

Question 15

Thermochemistry

Answer 15

Study of relationships btw chemical reactions and energy changes

Question 16

Energy

Answer 16

Capacity to do work or transfer heat

Question 17

Work

Answer 17

energy used to cause an object to move against a force

Question 18

Heat

Answer 18

energy used to cause objects temperature to increase

Question 19

Two types of energy

Answer 19

Kinetic and Potential

Question 20

Kinetic Energy

Answer 20

energy of motion-dependent on mass and velocity/speed

Question 21

Potential Energy

Answer 21

stored energy-stored btw bonds of molecules (potential energy is transferred to kinetic energy)

Question 22

Electrostatic Potential Energy

Answer 22

energy that comes from interaction of charged particles

Question 23

Units of Energy

Answer 23

Joule (J) and Calorie (cal)

Question 24

1 cal = ? J

Answer 24

4.184 J

Question 25

Cal

Answer 25

Calorie of food

Question 26

cal

Answer 26

calorie of energy

Question 27

1st Law of Thermodynamics

Answer 27

energy is conserved-neither created nor destroyed

Question 28

Endothermic

Answer 28

absorbs energy from surroundings (ex. ice melting)

Question 29

Exothermic

Answer 29

system gives off heat to surroundings (ex. combustion reaction)

Question 30

State Functions

Answer 30

property of a system-determined by specifying systems condition of state

Question 31

Enthalpies of Reactions (H)

Answer 31

Heat of RxN= Hproducts - Hreactants

Question 32

Hess’s Law

Answer 32

If RxN carries out in a series of steps, H = sum of enthalpy changes for individual steps

Question 33

Enthalpies of Formation

Answer 33

enthalpy change associated with formation of a cmpd from its elements (depends on state)

Question 34

Standard Enthalpy Change

Answer 34

enthalpy change when all reactants and products are in their standard states (1 atm and 25 degrees celsius)