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Flashcards in Phases and Phase Changes Deck (13):
1

What is heat capacity?

Heat capacity is the amount of heat required to raise 1 gram of substance/material by 1 degrees celsius

2

Why is the heat capacity the greatest for liquids compared to solids and gases?

Heat capacity is greatest for liquids because can store energy vibrationally and through translational kinetic energy. Solids can store energy only vibrationally. Gases can only store energy as translational energy.

3

Why do solids and liquids have a defined volume?

Solids and liquids are held together by intermolecular forces, though liquids are weaker.

4

Why is the enthalpy of vaporization greater in magnitude compared to the enthalpy of fusion?

Enthalpy of vaporization is the amount energy required to BREAK intermolecular bonds whereas enthalpy of fusion is the energy required only to WEAKEN the IMFs

5

What is heat capacity, specific heat capacity, and molar heat capacity? How does heat capacity relate to temperature?

Heat capacity is the the amount of heat energy transferred to a system to raise it one degree celsius. Specific heat capacity is the heat capacity per kg.
Smaller heat capacity means that less energy is required to raise 1 gram of the material by 1 degrees celsius. Therefore, if comparing two substances, the substance with the smaller heat capacity will increase to a higher temperature (assuming that both are given the same amount of heat energy)

6

When calculating the amount of heat required to raise a material by a certain degrees, be sure to account for enthalpy of fusion or vaporization if necessary

Front

7

What determines the magnitude of boiling point and the enthalpy of vaporization? What is the relationship between enthalpy of vaporization and boiling point?

If a substance has a lower boiling point than another, it can be concluded that its intermolecular forces are not as strong. If the intermolecular forces are not as strong, it can be inferred that it requires less heat energy to vaporize the substance.

8

What is the relationship between the slope of a heating curve and heat capacity?

Inversely related

9

What is the relationship between vapor pressure and temperature? What is the equation? What effect does IMFs play in determining the vapor pressure for a given temperature?

Clausius-Clapeyron

Vapor pressure is exponentially related to temperature. A substance with stronger IMFs will confer a decreased vapor pressure

10

What is the definition of boiling point in terms of pressure? What are its implications?

The boiling point is the temperature of a substance at which its vapor pressure is equal to the atmospheric pressure exerted on it. Therefore, a substance will have a smaller boiling point if atmospheric pressure is decreased.

11

Why is the boiling point of H2SO4 greater than that of water?

Though both experience hydrogen bonding, H2SO4 has more sites to accept hydrogen bonding

12

Why does molarity change with temperature andd pressure?

Molarity is moles solute per liter solution. Liter solution is volume. Volume is dependent on temperature based on Charles Law and dependent on pressure based on Boyle's Law

13

Why can't the Van't Hoff factor be measured by a density experiment?

Density is not a colligative property