Phases

Question 1

Relate phase changes and whether the change is an endo or exothermic reaction.

Answer 1

Gases require the highest amount of energy while solids require the lowest amount of energy. If a molecule goes towards gases then it is an endothermic reaction. If a mole goes towards the solid state then it is an exothermic reaction.

Question 2

What does delta H represent?

Answer 2

The change in enthalpy, whether the reaction is at a higher or lower energy level– endothermic or exothermic.

Question 3

What is isothermal?

Answer 3

Same temperature.

Question 4

What is isobaric?

Answer 4

Same pressure.

Question 5

What is isochronic?

Answer 5

Same volume.

Question 6

What is adiabatic?

Answer 6

No heat exchange.

Question 7

What is the triple point?

Answer 7

The point where all three phases are in equilibrium.

Question 8

What is the critical point?

Answer 8

The highest temperature and pressure where liquids can occur.

Question 9

What is the supercritical point?

Answer 9

Gases and liquids are indistinguishable.

Question 10

How can you identify water’s phase diagram?

Answer 10

negative slope along the solid and liquid line.

Question 11

Water trivia:

Answer 11

1. Liquid form is more dense than the solid form.

2. Extremely high boiling point for its size.

Question 12

What do the plateaus mean on heating curves?

Answer 12

The molecules are changing states. The plateaus occur at a CONSTANT temperature.

Question 13

What is heat capacity?

Answer 13

The amount of heat required to change one gram of a substance by one degree Celsius .

The flatter the slope(line), the greater the heat capacity

Question 14

Compare delta H of phases

Answer 14

Delta H Sublimation > Delta H Vaporization > Delta H Fusion.

Question 15

What is vapor pressure?

Answer 15

the pressure above the liquid when the forces of condensation and evaporation are at equilibrium.

Question 16

Relate vaporization rate with vapor pressure.

Answer 16

As the rate of vaporization increase, the vapor pressure decreases.

Question 17

Relate vapor pressure and boiling point.

Answer 17

As the boiling point of a liquid increases, then the vapor pressure decreases.

Question 18

Relate vapor pressure and temperature

Answer 18

As the temperature increases, then the vapor pressure increases EXPONENTIALLY.

Question 19

Relate hov, volatility, boiling point, and vapor pressure.

Answer 19

As the heat of vaporization increases, volatility decreases, boiling point increases, vapor pressure decreases.

Question 20

What are the two ways of defining boiling point? What are the consequences?

Answer 20

1. Boiling point is substance is no longer a liquid.
2. Boiling point is when the vapor pressure equals atm pressure.

This means, the lower the atm the lower the boiling point. Which is the case at higher elevation.

Question 21

What are three ways to effect boiling point?

Answer 21

1. Increase solute concentration to increase BP.
2. Increase elevation so the atm pressure is lower to DECREASE BP.
3. Decrease elevation so there is more atm pressure to increase Bp.

Question 22

What is Raoult’s Law?

Answer 22

The Vapor pressure = (X/ total moles) Pure vapor pressure.

Question 23

What do solutes do the melting and boiling point of a solution?

Answer 23

Decrease melting point and increase boiling point.

Question 24

What is the formula for freezing point depression and boiling point elevation

Answer 24

Tx= Kim

Question 25

What is the formula for osmotic pressure?

Answer 25

osmotic pressure = iRMT.