thermochemistry

Question 0

What is the kinetic molecular theory and energy?

Answer 0

Kinetic molecular theory: substances are composed of particles that are continually moving and colliding with particles

Question 1

Definition of thermochemistry?

Answer 1

The study of energy/heat transfer involved during chemical reactions

Question 2

What is kinetic energy?

Answer 2

Energy of motion

Question 3

What is potential energy

Answer 3

Energy that is stored

Question 4

He is a form of what?

Answer 4

Energy(q) units:joules

Question 5

What happens in a chemical reaction

Answer 5

Can result in the breaking and forming of chemical bonds (which requires energy)

Question 6

what is temperature

Answer 6

A measure of the average kinetic energy of the particles that make up a substance or system

Question 7

The temperature change is explained the change in what?

Answer 7

A change in Kinetic energy

Question 8

What is heat(q)?

Answer 8

Heat refers to the transfer of kinetic Energy between objects with different temperatures

Question 9

What is the first law of thermodynamics?

Answer 9

Any change in the energy of a system is equivalent buy an opposite change in the energy of the surroundings
q=-q

Question 10

A negative sign denotes heat loss and is what?

Answer 10

Exothermic

Question 11

A positive sign denotes heat gained and is what?

Answer 11

Endothermic

Question 12

What is a system

Answer 12

Area where reaction takes place (generally is the reaction)

Question 13

What is the surroundings?

Answer 13

Area outside of the system

Question 14

Describe the three types of systems we are interested in

Answer 14

• open system= both matter and energy can freely cross from the system to the surroundings and back. Ex. An open test tube
• closed system= Energy can cross the boundary that matter cannot. Ex. A sealed test tube

-isolated system= neither matter nor energy can cross between the system and the surroundings
Ex. The universe

Question 15

Definition of specific Heat capacity

Answer 15

The energy required to change 1 g of a substance by 1°C

Units: j/g•°c

Question 16

What is the specific heat capacity formula

Answer 16

q=mc^T

Question 17

What is heat capacity(C)?

Answer 17

Relation of heat of a sample/object/system to its change in temperature

Question 18

How do you calculate heat capacity

Answer 18

C= m•c or q=C^T

Question 19

What is enthalpy(^H)?

Answer 19

“Heat of reaction”
Chemical reactions in phase changes involve changes in potential energy, not kinetic
-for each chemical reaction at SATP, there is a specific enthalpy change

Question 20

What is the formula for calculating the heat absorbed or released by chemical reaction

Answer 20

q= n•^H

Question 21

What is a phase change

Answer 21

A change in matter without any change in chemical composition of the system

Question 22

There is constant temperature during a phase change why is this?

Answer 22

Because this is not a change energy therefore the temperature is the same, potential energy changes

Question 23

Why does it cause so much more energy for chemical reaction to take place than a phase change

Answer 23

Because a chemical reaction requires stronger ionic covalent bonds be broken, but a phase change only requires intermolecular bonds to be broken

Question 24

What are the phase changes?

Answer 24

S>L is melting or fusion
L>G is vaporization 
G>L is condensation 
L>S is solidifying(freezing)
G>S is sublimation 
S>G is sublimation

Question 25

What does a heating and cooling curve show

Answer 25

Shows how temperature and phase changes of a substance

Question 26

How do you calculate the total energy change of a system

Answer 26

q(total)=q1 + q2 + q3 etc.

Question 27

What is standard molar enthalpy of formation

Answer 27

One mole of compound is formed from substances (elements) in their standard states. ^H°f