Chemistry Chapter 12 - Liquids and Solids

Questions and Answers

What is the heat of fusion of H2O?

6.02 kJ/mol

What is the molar mass of water?

18.02 grams

How many moles are in 34.2 g of H2O?

1.898 mol

What is the total heat for 34.2 g of H2O?

11.4 kJ Signup and view all the answers

What is sublimation?

Sublimation is a physical change in which a substance is converted from its solid form directly into a gaseous form. Signup and view all the answers

What determines the state of a substance?

The strength of the intermolecular forces between the molecules or atoms that compose the substance. Signup and view all the answers

What is dispersion force?

Dispersion force is an intermolecular force present in all molecules and atoms. Signup and view all the answers

What is an instantaneous dipole?

Instantaneous dipole is a type of intermolecular force resulting from transient shifts in electron density within an atom or molecule. Signup and view all the answers

Which halogen has the higher boiling point, Cl2 or I2?

I2 Signup and view all the answers

Which hydrocarbon has the higher boiling point, CH4 or C2H6?

C2H6 Signup and view all the answers

Which substance has the highest boiling point? Why? a) CH4, b) CH3CH3, c) CH3CH2CH3, ______

d) CH3CH2CH2CH3 Signup and view all the answers

What is a dipole-dipole force?

A dipole-dipole force exists in all polar molecules. Signup and view all the answers

What is a permanent dipole?

A permanent dipole is a separation of charge due to unequal sharing of electrons between atoms. Signup and view all the answers

What is miscibility?

Miscibility is the ability of two liquids to mix without separating into two phases. Signup and view all the answers

Determine whether each molecule has dipole-dipole forces: a) CO2, b) CH2Cl2, c) CH4.

a) No, b) Yes, c) No Signup and view all the answers

Determine whether or not each molecule has dipole-dipole forces: a) CI4, b) CH3Cl, c) HCl.

a) No, b) Yes, c) Yes Signup and view all the answers

What is a hydrogen bond?

A hydrogen bond is a strong dipole-dipole interaction between molecules containing hydrogen bonded to a small electronegative atom. Signup and view all the answers

Three molecular compounds A, B, and C have nearly identical molar masses. What is most likely to be the relative order of their boiling points? ______, b) C < B < A, c) B < C < A

a) A Signup and view all the answers

What is an ion-dipole force?

The ion-dipole force occurs in mixtures of ionic compounds and polar compounds. Signup and view all the answers

What is the relative strength of dispersion forces?

Weak but increases with increasing molar mass. Signup and view all the answers

What is the relative strength of dipole-dipole forces?

Moderate relative strength. Signup and view all the answers

What is the relative strength of hydrogen bond forces?

Strong. Signup and view all the answers

What is the relative strength of ion-dipole forces?

Very strong. Signup and view all the answers

When dry ice sublimes, what forces are overcome?

Dispersion forces between carbon dioxide molecules. Signup and view all the answers

What is a molecular solid?

A molecular solid is a solid whose composite units are molecules. Signup and view all the answers

What are ionic solids?

Ionic solids are composed of metals and nonmetals joined by ionic bonds. Signup and view all the answers

What is an atomic solid?

An atomic solid is a solid whose component units are individual atoms. Signup and view all the answers

What is a covalent atomic solid?

Covalent atomic solids are held together by covalent bonds. Signup and view all the answers

What is a nonbonding atomic solid?

A nonbonding atomic solid is held together by relatively weak dispersion forces. Signup and view all the answers

What is a metallic atomic solid?

Metallic atomic solids are held together by metallic bonds. Signup and view all the answers

What holds together covalent solids and what is their melting point?

Covalent bonds; they have high melting points. Signup and view all the answers

What holds together nonbonding solids and what is their melting point?

Dispersion forces; they have low melting points. Signup and view all the answers

What are intermolecular forces?

Intermolecular forces are attractive forces that exist between molecules. Signup and view all the answers

What is thermal energy?

Thermal energy is the energy associated with the motion of molecules and atoms. Signup and view all the answers

What will a sample be if the intermolecular forces are weak?

The sample will likely be gaseous. Signup and view all the answers

What will a sample be if the intermolecular forces are strong?

The sample will likely be liquid or solid. Signup and view all the answers

What are the properties of liquids?

<ol> <li>High densities compared to gases 2) Indefinite shape 3) Definite volume</li> </ol> Signup and view all the answers

What are the properties of solids?

<ol> <li>High densities compared to gases 2) Definite shape 3) Definite volume 4) May be crystalline or amorphous.</li> </ol> Signup and view all the answers

What is the density of gas?

The density of gas is low. Signup and view all the answers

What is the density of liquid?

The density of liquids is high. Signup and view all the answers

What is the density of solid?

The density of solids is high. Signup and view all the answers

What is the shape of gases?

The shape of gases is indefinite. Signup and view all the answers

What is the shape of liquids?

The shape of liquids is indefinite. Signup and view all the answers

What is the shape of solids?

The shape of solids is definite. Signup and view all the answers

What is the volume of a gas?

A gas's volume is indefinite. Signup and view all the answers

What is the volume of a liquid?

A liquid's volume is definite. Signup and view all the answers

What is the volume of a solid?

A solid's volume is definite. Signup and view all the answers

What is the strength of intermolecular forces of a gas?

The strength of intermolecular forces of a gas is weak. Signup and view all the answers

What is the strength of intermolecular forces of a liquid?

The strength of intermolecular forces of a liquid is moderate. Signup and view all the answers

What is the strength of intermolecular forces of a solid?

The strength of intermolecular forces of a solid is strong. Signup and view all the answers

What is an example of a gas?

An example of a gas is carbon dioxide (CO2). Signup and view all the answers

What is an example of a liquid?

An example of a liquid is water (H2O). Signup and view all the answers

What is an example of a solid?

An example of a solid is sugar. Signup and view all the answers

Why do liquids have high densities in comparison to gases?

Liquids have high densities in comparison to gases because their molecules are much closer together. Signup and view all the answers

Why do solids have high densities in comparison to gases?

Solids have high densities in comparison to gases because their molecules are close together. Signup and view all the answers

Which has a higher density, a liquid or a gas?

The densities of solids are usually greater than those of the corresponding liquids. Signup and view all the answers

A substance has a definite shape and definite volume. What is the state of the substance?

Solid Signup and view all the answers

Would molecular solids and liquids exist without intermolecular forces?

False Signup and view all the answers

What is surface tension?

Surface tension is the tendency of liquids to minimize their surface area. Signup and view all the answers

What is viscosity?

Viscosity is the resistance of a liquid to flow. Signup and view all the answers

What is evaporation?

Evaporation is the process in which liquid molecules acquire enough energy to enter the gas phase. Signup and view all the answers

What is vaporization?

Vaporization is the phase transition between a liquid and a gas. Signup and view all the answers

What is volatile?

Volatile is the tendency to vaporize quickly. Signup and view all the answers

What is nonvolatile?

Nonvolatile describes a compound that does not vaporize easily. Signup and view all the answers

What is condensation?

Condensation is a physical change in which a substance is converted from its gaseous form to its liquid form. Signup and view all the answers

What is dynamic equilibrium?

Dynamic equilibrium is the condition in a chemical reaction where the rates of forward and reverse reactions are equal. Signup and view all the answers

What is vapor pressure?

Vapor pressure is the partial pressure of a vapor in dynamic equilibrium with its liquid. Signup and view all the answers

In general, the rate of vaporization increases with....

Increasing surface area, increasing temperature, and decreasing strength of intermolecular forces. Signup and view all the answers

What is the opposite of condensation?

The opposite of condensation is evaporation. Signup and view all the answers

What is the opposite of evaporation?

The opposite of evaporation is condensation. Signup and view all the answers

What is boiling point?

Boiling point is the temperature at which the vapor pressure of a liquid equals the pressure above it. Signup and view all the answers

What is normal boiling point?

Normal boiling point is the boiling point of a liquid at a pressure of 1 atmosphere. Signup and view all the answers

The gas over a rapidly boiling pot of water is sampled and analyzed. Which substance composes a large fraction of the gas sample?

H2O (g) Signup and view all the answers

Is evaporation endothermic?

True Signup and view all the answers

Is condensation exothermic?

True Signup and view all the answers

What is heat of vaporization?

Heat of vaporization is the amount of heat required to vaporize one mole of a liquid at its boiling point without a temperature change. Signup and view all the answers

What is the heat of vaporization of water?

The heat of vaporization of water at its normal boiling point is 40.7 kJ/mol. Signup and view all the answers

Is vaporization endothermic?

True Signup and view all the answers

What is the heat of vaporization of isopropyl alcohol?

The heat of vaporization of isopropyl alcohol is 39.9 kJ/mol. Signup and view all the answers

What is the heat of vaporization of acetone?

The heat of vaporization of acetone is 29.1 kJ/mol. Signup and view all the answers

What is the heat of vaporization of diethyl ether?

The heat of vaporization of diethyl ether is 26.5 kJ/mol. Signup and view all the answers

Calculate the amount of heat required to vaporize 25.0 g of water at its boiling point.

The heat required is 56.5 kJ. Signup and view all the answers

Calculate the amount of water in grams that can be vaporized at its boiling point with 155 kJ of heat.

The amount is 68.6 grams of H2O. Signup and view all the answers

Calculate the amount of heat in kJ required to vaporize 2.58 kg of water at its boiling point.

The heat required is 5837.2 kJ. Signup and view all the answers

A drop of water weighing 0.48 g condenses on the surface of a 55 g block of aluminum that is initially at 25 degrees C. If the heat released during condensation goes only toward heating the metal, what is the final temperature in Celsius of the metal block?

The final temperature of the metal block is 48.6 degrees C. Signup and view all the answers

How much heat is required to vaporize 33.8 g of water at 100 degrees C?

The heat required is 76.3 kJ. Signup and view all the answers

How much heat does your body lose when 2.8 grams of sweat evaporates from your skin at 25 degrees C?

The heat lost is 6.8 kJ. Signup and view all the answers

How much heat is emitted when 4.25 g of water condenses at 25 degrees C?

The heat emitted is 10.4 kJ. Signup and view all the answers

When water condenses on a small metal block, what would you expect to happen to the temperature of the metal block?

The temperature of the metal block increases. Signup and view all the answers

What happens as the temperature of a solid increases?

The molecules and atoms in the solid vibrate faster. Signup and view all the answers

What is melting point?

Melting point is the temperature at which a solid turns into a liquid. Signup and view all the answers

What is the temperature of a mixture of water and ice?

The temperature is 0 degrees C at 1 atm pressure. Signup and view all the answers

Is melting endothermic?

True Signup and view all the answers

Is freezing endothermic?

False Signup and view all the answers

What is heat of fusion?

Heat of fusion is the amount of heat required to melt one mole of a solid at its melting point. Signup and view all the answers

What is the heat of fusion of water (H2O) at melting point?

The heat of fusion for water is 6.02 kJ/mol. Signup and view all the answers

What is the heat of fusion of isopropyl alcohol at melting point?

The heat of fusion of isopropyl alcohol is 5.37 kJ/mol. Signup and view all the answers

What is the heat of fusion of acetone at melting point?

The heat of fusion of acetone is 5.69 kJ/mol. Signup and view all the answers

What is the heat of fusion of diethyl ether at melting point?

The heat of fusion of diethyl ether is 7.27 kJ/mol. Signup and view all the answers

Calculate the amount of heat required to melt 25.0 g of ice at 0 degrees C.

The heat required is 8.35 kJ. Signup and view all the answers

Calculate the amount of ice in grams that, upon melting at 0 degrees, absorbs 237 kJ of heat.

The amount is 709 g of H2O. Signup and view all the answers

Calculate the amount of heat absorbed when a 15.5 g ice cube melts at 0 degrees C.

The heat absorbed is 5.18 kJ. Signup and view all the answers

How much heat is required to melt 37.4 g of ice at 0 degrees C?

The heat required is 12.5 kJ. Signup and view all the answers

How much energy is released when 34.2 g of water freezes?

The energy released is calculated based on the heat of fusion. Signup and view all the answers

Study Notes

Intermolecular Forces

Intramolecular forces are attractive forces between molecules.
Intermolecular forces are crucial for determining the states of matter: solid, liquid, or gas.

Thermal Energy

Thermal energy correlates to the random motion of molecules, increasing with temperature.

States of Matter

Weak intermolecular forces lead to gaseous samples; strong intermolecular forces result in liquids or solids.
Liquids exhibit high density compared to gases, assume the shape of their containers, and possess definite volume.
Solids also have high density, retain definite shape, and definite volume, and can be crystalline or amorphous.

Properties of Gases, Liquids, and Solids

Gases have indefinite shape and volume, while liquids have definite volume with indefinite shape.
The density of gases is low, while liquids and solids are significantly denser.
Intermolecular forces strength is weak in gases, moderate in liquids, and strong in solids.

Viscosity and Surface Tension

Viscosity measures a liquid's resistance to flow; more viscous liquids flow slowly.
Surface tension results in a skin-like surface on liquids, driven by cohesive forces.

Phase Changes

Evaporation is the endothermic process converting liquid to gas; vaporization includes all types of phase transitions from liquid to gas.
Condensation is exothermic, converting gas to liquid; dynamic equilibrium occurs when the rates of evaporation and condensation balance.

Vapor Pressure

Vapor pressure is the equilibrium pressure of vapor above a liquid and rises with higher temperature and weaker intermolecular forces.
Vaporization increases with greater surface area and higher temperatures.

Boiling and Melting Points

Boiling point is when vapor pressure equals external pressure; normal boiling point occurs at 1 atmosphere.
Melting point is when solids convert to liquids, requiring added thermal energy to overcome intermolecular forces.

Heat Absorption and Release

Heat of vaporization refers to energy needed to vaporize a mole of liquid; water's heat of vaporization is 40.7 kJ/mol at boiling point.
Heat of fusion is the energy required to melt a mole of solid; water's heat of fusion is 6.02 kJ/mol at its melting point.

Specific Calculations

Calculating energy for phase changes involves using molar mass and corresponding heats of fusion or vaporization, integrating concepts of moles and kJ required.

Additional Concepts

Sublimation describes substances transitioning from solid to gas without becoming liquid.
Dispersion forces are present in all molecules, caused by electronic distribution fluctuations, contributing to intermolecular strength.
Higher molar mass generally correlates with stronger dispersion forces and therefore higher boiling points, as seen in comparisons like Cl2 vs I2 and CH4 vs C2H6.

Key Concepts on Temperature Changes

As temperature increases, solids vibrate faster, and phase transitions like melting absorb heat while freezing releases heat, leading to temperature increases in surrounding materials during condensation.### Molecular Structure and Molar Mass
CH4 (methane): Molar mass is 16.0426 grams.
CH3CH3 (ethane): Molar mass is 30.0690 grams.
CH3CH2CH3 (propane): Molar mass is 44.0596 grams.
CH3CH2CH2CH3 (butane): Molar mass is 58.1222 grams; has the highest molar mass, leading to stronger dispersion forces and highest boiling point.

Intermolecular Forces

Dipole-Dipole Force: Present in polar molecules; arises due to permanent dipoles.
Permanent Dipole: Results from unequal electron sharing, leading to a molecule having distinct positive and negative ends.
Miscibility: Refers to liquids' ability to mix without separating into layers.

Polarity Determination

CO2: Linear structure with polar bonds that cancel out, resulting in no dipole moment; hence, no dipole-dipole forces.
CH2Cl2: Tetrahedral structure with differing polar bonds; non-canceling dipoles lead to a net dipole moment and dipole-dipole forces.
CH4: Tetrahedral structure with nearly nonpolar bonds that cancel out; nonpolar and no dipole-dipole forces.

Molecular Behavior

CI4: Nonpolar, hence no dipole-dipole forces.
CH3Cl: Polar, therefore exhibits dipole-dipole forces.
HCl: Polar and has dipole-dipole forces.

Hydrogen Bonds

Hydrogen Bond: A strong intermolecular force occurring when hydrogen is bonded to highly electronegative atoms like N, O, or F.

Boiling Points of Molecular Compounds

For three similar molar mass compounds: Nonpolar (A) < Polar (B) < Hydrogen Bonding (C). Nonpolar has lowest boiling point due to dispersion forces only. Polar has mid-range boiling point with dipole-dipole interactions, while hydrogen bonding in C gives it the highest boiling point.

Types of Intermolecular Forces

Ion-Dipole Force: Strong interaction found in mixtures of ionic and polar compounds; particularly significant in ionic solutions.
Dispersion Forces: Weak yet present in all molecules and increase with molar mass. Example: H2.
Dipole-Dipole Forces: Moderate strength, only seen in polar molecules. Example: HCl.
Hydrogen Bonding: Strong forces present when H is attached to F, O, or N. Example: HF.
Ion-Dipole Forces: Very strong, important for ionic and polar compound interactions.

Changes of State

Sublimation of dry ice (solid CO2) overcomes dispersion forces between molecules.

Types of Solids

Molecular Solids: Composed of molecules held together by various intermolecular forces such as dispersion, dipole-dipole, and hydrogen bonds.
Ionic Solids: Composed of cations and anions joined by ionic bonds, held together by electrostatic attractions.
Atomic Solids: Comprised of individual atoms, further categorized into:
- Covalent Atomic Solids: Maintained by covalent bonds, e.g., diamond; characterized by high melting points.
- Nonbonding Atomic Solids: Held by dispersion forces, resulting in low melting points.
- Metallic Atomic Solids: Maintain structure through metallic bonds involving positively charged ions in a sea of electrons.

Melting Points

Covalent Solids: High melting points due to strong covalent bonds.
Nonbonding Solids: Low melting points attributed to weak dispersion forces.

Studying That Suits You

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Explore the key concepts of Chapter 12 concerning liquids, solids, and intermolecular forces through these flashcards. This interactive quiz will help you understand essential definitions, including intermolecular forces and thermal energy. Test your knowledge and reinforce your understanding of these critical chemistry topics.