Chapter 7 - Liquids and Solids

Which physical state involves rigid intramolecular bonds to give fixed 3D structures?

Solids

What is intermolecular forces?

They are attractive or repulsive interactions between neighboring molecules

What physical properties does intermolecular forces determine?

Boiling point, melting point, solubility and density

What is intramolecular forces?

They are interactions within a molecule that hold atoms together

What are some intramolecular forces?

Covalent, ionic, metallic, and hydrogen bonds

Are intermolecular forces stronger or weaker than intramolecular forces?

Weaker

What are the 3 major types of intermolecular forces?

London dispersion forces (LDFs), dipole-dipole interactions, and hygroden bonds

What is surface tension?

The ability of a liquid surface to resist external forces

What does viscosity refers to?

The measure of a fluid’s resistance to flow or deformation

What are the 4 types of solids?

Ionic, metallic, covalent network, and molecular

How are ionic solids held together?

Held by ionic bonds

How are metallic solids held together?

Metallic solids are held together by a sea of free electrons flowing around a lattice of metal cations

How are covalent network solids held together?

Network of covalent bond

Are ionic solids conductive of electricity?

No, they are non-conductive

How are molecular solids held together?

Intermolecular forces. E.g. hydrogen bonds, dipole-dipole, and dispersion forces (Van der Waals)

Are metallic solids malleable and ductile?

Yes

Which type of solid is conductive?

Metallic solids

Which type of solids are non-conductive?

Ionic, covalent network, and molecular

Molecular solids can be describes as?

Soft, non-conductive and have low melting points

Covalent network solids can be described as?

Hard, non-conductive and have a high melting points

Metallic solids can be described as?

Malleable, ductile, conductive, have high luster, and variable melting points and hardness

Ionic solids can be described as?

Hard, non-conductive, brittle, and have high melting points

Is glass crystalline or amorphous?

Amorphous

How do amorphous solids arrange themselves?

No long-range molecular pattern or order to them

How do crystalline solids arrange themselves?

They form an orderly array of molecules that follow a repeating pattern

How are atoms arranged in a simple cubic?

1 atom per unit cell; one atom at every corner of cube

How are atoms in a body-centered cubic?

2 atoms per unit cell; one atom at centre of cube and one atom at every corner of cube

How are atoms arranged in a face-centered cubic?

4 atoms per unit cell; one atom at the centre of all the faces of the cube and at every corner of the cube

How are liquid molecules held together?

Intermolecular forces such as hydrogen bonding, dipole-dipole, and van der Waals

How does the intermolecular force, van der Waals, occur?

Caused by random shifts in electron density of particles that create temporary weak poles (charge centres) that attract other particles

Do van der Waals forces occur on all molecules?

Yes

Do van der Waals interactions increase with particle size?

Yes

How does the intermolecular force, dipole-dipole, occur?

Occurs between molecules with a permanent uneven distribution of elections

How does the intermolecular force, hydrogen bonds, occur?

Occurs when a a hydrogen atom bonded to a highly electronegative atom (i.e. N, O, F) forms attractions with another highly electronegative atom (i.e. N, O, F)

Which three non-metal elements can form hydrogen bonds with hydrogen?

Fluorine, nitrogen, and oxygen

What term describes the degree to which a solute can be dissolved in a liquid?

Solubility

What term describes the degree to which a liquid can be mixed with another liquid?

Miscibility

What is vapor pressure?

The pressure exerted exerted by a liquid against the atmosphere.

What occurs when the vapor pressure of a liquid equals or exceeds the atmospheric pressure?

Boiling occurs

Do stronger intermolecular forces lead to higher boiling point?

Yes

Do stronger intermolecular forces lead to higher viscosity?

Yes

Do stronger intermolecular forces lead to higher surface tension?

Yes

Do stronger intermolecular forces lead to higher vapor pressure?

No, they lead to lower vapor pressure. A liquid with stronger intermolecular forces has a lower vapor pressure because its molecules are more tightly bound together, making it harder for them to escape the liquid phase

What is at equilibrium at the triple point?

The gas, liquid, and solid phases

What is the critical point?

The point on the phase diagram at which the liquid and gas phases are indistinguishable

The solid-liquid boundary is represented by what line?

The fusion / melting curve

The liquid-gas boundary is represented by what line?

The vaporization curve

The solid-gas boundary is represented by what line?

The sublimation curve

At 1 atm and 0°C, what is occurring simultaneously to water?

The water will be freezing and melting simultaneously

What happens as you gradually increase temperature from 0°C at 1 atm?

Forward melting reaction will gradually outpace the freezing reaction. Eventually, water will reach an equilibrium where it is completely liquid

What is crystallization or freezing?

The transition from liquid to solid

What is another term for fusion in regards to physical states?

Melting

What is sublimation?

Solid transitioning directly to a vapor form without first becoming a liquid

What is deposition?

Gas transitioning directly to solid form without first becoming a liquid

What is vaporization?

Liquid transitioning into gas form

What is condensation

Gas transitioning into liquid form

Is dry ice an example of sublimation or deposition?

Sublimation, as gas is emitted from the dry ice without first converting into liquid

Does latent heat increase temperature of the object?

No, the heat is transferred into breaking or forming intermolecular bonds to result in a phase change

What is known as the energy 'cost' of phase change?

Latent heat or heat of transformation

Which phase changes are exothermic?

Crystallization/freezing, condensation, deposition

Which phase changes are endothermic?

Fusion/melting, vaporization, sublimation

What is Endothermic?

When heat is absorbed and when a phase change requires heat to proceed

What is Exothermic?

When heart is released during a phase change

What is entropy (S)?

The disorder or randomness in a system

What does a positive

An increase in disorder within a system

What does a negative S value indicate?

A decrease in disorder within a system or increase in order.

What is enthalpy (H)?

The energy or heat measurement in a thermodynamics system

What does H or change in enthalpy represent?

The amount of heat gained or lost at constant pressure

What states does enthalpy depend on?

It depends only on the initial and final states of a system

What does it mean if H > 0?

Heat moves into the system and the reaction is endothermic

What does it mean if H < 0?

Heat moves out of the system and the reaction is exothermic

Why is heat of vaporization is greater than heat of fusion?

Vaporization requires a lot of energy to break all forces of attraction while fusion requires only enough for molecules to escape site in solid crystal lattice

Why is heat of sublimation greater than heat of vaporization?

Solids have stronger intermolecular forces and take higher amount of energy to break those bonds