MCAT CHEM CH. 7

Question 1

What happens to the intramolecular bonds during a physical change?

Answer 1

Nothing; none are made or broken

Question 2

What does a physical change affect based on the matter?

Answer 2

Affects only intermolecular forces between molecules and atoms

Question 3

What are intramolecular forces?

Answer 3

Intramolecular forces are the forces that hold atoms together within a molecule.

Question 4

What are intermolecular forces?

Answer 4

Intermolecular forces are forces that exist between molecules.

Question 5

What force holds matter together as solid or liquid?

Answer 5

Intermolecular forces

Question 6

Physical changes are closely related to what?

Answer 6

Temperature

Question 7

What is temperature?

Answer 7

A measure of the amount of internal kinetic energy that molecules have

Question 8

What is kinetic energy related to?

Answer 8

Related to degree of disorder (entropy)

Question 9

Phase changes are a result of….

Answer 9

breaking or forming intermolecular interactions

Question 10

Why are the molecules held in a solid when temperature decreases?

Answer 10

Don’t have enough kinetic energy to overcome the intermolecular forces

Question 11

What happens when you add heat to a solid?

Answer 11

Loosens the intermolecular interactions and increases entropy

Question 12

What is fusion? What is vaporization? What is condensation? What is crystallization? What is sublimation? What is deposition?

Answer 12

Solid to liquid, liquid to gas, gas to liquid, liquid to solid

Question 13

What happens at a molecular level to the molecules inside a liquiud?

Answer 13

The moelcuels in a liquid are still in contact and interact with each other, but they have enough kinetic energy to escape fixed positions

Question 14

What is heat of trasition?

Answer 14

The amount of energy required to complete a transition

Question 15

What is heat of fusion?

Question 16

What is heat of vaporization?

Answer 16

The energy absorbed when a liquid changes to a gas

Question 17

What is the equation for the amount of heat accompanying a phase transition?

Answer 17

Question 18

What does n represent in the equation q = n X delta H_{phase change}

Answer 18

The number of moles of the substance

Question 19

What happens when delta H and q are positive, based on the phase transition equation?

Answer 19

Heat is absorbed

Question 20

What happens when delta H and q are negative, based on the phase transition equation?

Question 21

What is a calorie?

Answer 21

The amount of heat required to raise the temperature og 1 gram of water by 1°C

Question 22

What is the SI unit of heat?

Answer 22

Joule

Question 23

What is the conversion between calorie and joule?

Answer 23

1 cal = 4.2 J

Question 24

What we talk about a temperature change, what are we considering?

Answer 24

Cases where the phase doesn’t change, temperature is absorbed or released without any change

Question 25

What a substance absorbs or releases heat, one of the two things can happen, what are they?

Answer 25

Temperature changes or phase changes but not both at the same time

Question 26

The amount of heat absrobed or released by a sample is proportional to what…?

Answer 26

To its change in temperature

Question 27

What is the constant of proportionality?

Answer 27

The substance’s heat capacity, C

Question 28

What is C, heat capacity, the product of?

Question 29

What is the amount of heat, q, equation we can write that includes heat capacity?

Answer 29

Question 30

What do each variable mean in the q = mc∆T

Answer 30

q = heat added or released by the sample

Question 31

What type of property is a substance’s specific heat? What does it tell us?

Answer 31

Intrinsic property

Question 32

What is the relationship between temperature change and substance’s heat capacity?

Answer 32

Inversely proportional

Question 33

The specific heat of a substance also depends on what…?

Answer 33

Phases; liquid c would not be ice c

Question 34

What is the conversion between joules and calories?

Answer 34

4.2 J

Question 35

What happens if you see 4.2 J/g•K and they ask you to give it in celsius?

Question 36

Once a solid reaches its melting point, what happens to the absorbed heat?

Answer 36

Absorbed heat is used to change the phase to liquid, not to inrease the temperature

Question 37

What is phase transition diagram or heating curve?

Question 38

Draw a phase transition diagram?

Question 39

The greater the value of the heat transition, based on the phase transitional diagram….

Question 40

What is the relation based on heat of fusion and heat of vaporization?

Question 41

What is the triple point in the phase diagram?

Question 42

What is the critical point?

Answer 42

Marks the end of the liquid-gas boundary

Question 43

What is the superifcial liquid?

Answer 43

Beyond the critical point, where the substance displays both gas and liquid properties

Question 44

What does the solid phase favour?

Question 45

What does the gas phase favour?

Question 46

If we draw a horizontal line at the “1 atm” pressure level, the tempoerature at the point where the line crosses the solid-liquid boundary is what?

Answer 46

The normal melting point

Question 47

If we draw a horizontal line at the “1 atm” pressure level, the tempoerature at the point where the line crosses the liquid-gas boundary is what?

Question 48

Which form is denser for water? I. Liquid II. Solid

Question 49

How does the phase diagram of water differ?

Answer 49

The solid-liquid boundary line has a negative slope

Question 50

An increase in pressure for water favours what?

Answer 50

The liquid phase