Ch. 7/ Solids Liquids and Gases Flashcards by Mel El Mar

What are the 3 states of matter?

Gases
Solids
Liquids

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What is the shape and volume of a gas, solid, and liquid?

• a gas expands to fill its container

• a liquid has a fixed volume that takes the shape of the container and occupies

• a solid has a definite shape and volume

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What is the arrangement of particles of a gas, liquid, and solid?

• a gas is randomly arranged, disorganized, and far apart

• a liquid is randomly arranged, but close

• a solid has a fixed arrangement of very close particles

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What is the density, particle movement, and interaction between particles of a gas, liquid, and solid?

•Gas
- Low density (<0.01 g/mL)
-particle movement is very fast
- there is no interaction between particles

•Liquid
- High density (~ 1 g/mL)^a
- Particle movement is moderate
- interaction between particles is strong

•Solid
- High density (1-10 g/mL)
- Particle movement is slow
- Interaction between particles is very strong

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Existing as a gas, liquid, or solid, depends on:

The balance between the kinetic energy of its particles.
The strength of the interactions between the particles.

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PROPERTIES OF GASES 📍

What is the kinetic molecular theory of gases?

A gas consist of particles that move randomly and rapidly.
The size of gas particles is small compared to the space between the particles.
Particles exert no attractive forces on each other.
The kinetic energy of gas particles increases with increasing temperature.
When particles collide with each other, they rebound and travel in new directions.
When gas particles collide with the walls of a container, they exert a pressure.
Pressure (P) is the force (F) exerted per unit area (A).

Pressure = Force/ Area = F/A

1 atmosphere (atm)=
760. mmHG
760. torr
14.7 psi
101,325 Pa

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GAS LAWS 📍
What is Boyle’s law? What does it State?

Boyles law: for a fixed amount of gas at constant temperature, the pressure and volume of gas are inversely related.

• if one quantity increases, the other decreases

• the product of the two quantities is a constant, K.

Pressure • volume = constant

P x V = k

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GAS LAWS
BOYLE’S LAW

If the volume of a cylinder of gas is halved, the pressure of the gas inside the cylinder doubles.

What equation can explain this behavior ?

Pg 7

P1V1 = P2V2

Initial New
Conditions Conditions

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To learn how to use Boyle’s Law to calculate a new gas, volume, or pressure see slides 8-10.

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GAS LAWS
CHARLES’S LAW

What is Charles’s law?

Charles is law: for a fixed amount of gas at constant pressure, the volume of the gas is proportional to its Kelvin temperature.

• if one quantity increases, the other increases as well

• dividing volume by temperature temperature is a constant, K

Volume/ temperature = constant

V/T= K

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GAS LAWS
CHARLES’S LAW

If the temperature of a cylinder is doubled, the volume of the gas inside the cylinder doubles.

What equation explains this behavior ?

V1/T1 = V2/T2
Initial New
Conditions Conditions

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GAS LAWS
GAY-LUSSAC’S LAW

What is Gay-Lussac’s Law?

Gay-Lussac’s Law: for a mixed amount of gas at constant value, the pressure of a gas is proportional to its kelvin temperature.

• if one quantity increases, the other increases as well

• dividing pressure by temperature is a constant, k

Pressure/ temperature = constant
P/T = k

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GAS LAWS
GAY-LUSSAC’S LAW

Increasing the temperature increases the kinetic energy of the gas particles, causing the pressure exerted by the particles to increase.

What equation explains this behavior?

P1/ T1 = P2/T2

Initial New
Conditions Conditions

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Gas Laws

What is the combined gas law?

• all three gas laws can be combined into one equation.

P1V1/T1 = P2V2/T2

Initial New
Conditions Conditions

• this equation is used for DETERMINING the EFFECT OF CHANGING TWO FACTORS
(e.g., P and T) on the third factor V.

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GAS LAWS

What is the combined gas law used for? ✨✨✨✨ what does that mean ?

P1V1/T1 = P2V2/T2

Initial New
Conditions Conditions

• This equation is used for DETERMINING the EFFECT OF CHANGING TWO FACTORS
(e.g., P and T) on the third factor V.

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Avogadro’s law

What is Avogadro’s law?

Avogadro’s law: when the pressure and temperature are held constant, the volume of big gas is proportional to the number of moles present.

• if one quantity increases, the other increases as well

• dividing the volume by the number of moles is a constant, K

Volume/ Number of moles = constant

V/n = k

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Avogadro’s law

If the number of moles of gas in a cylinder is increased, the volume of the cylinder will increase as well.

What equation can be used to explain this behavior?

V1/n1 = V2/n2

Initial New
conditions conditions

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Avogadro’s law

What is STP and what does it stand for?

See pg 22- 32 for more info

HOW DO I KNOE EHICH TO USE?!?!?
SLIDE 30

• often amounts of gas are compared at a set of standard conditions of temperature and pressure, abbreviated as STP.

• STP conditions are:

1 atm (760 mm Hg) for pressure
273 K (0°C) for temperature

• At STP, 1 mole of any gas has a volume of 22.4 L

• 22.4 L is called the standard molar volume

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INTERMOLECULAR FORCES, BOILING POINT, AND MELTING POINT

What are intermolecular forces?

• intermolecular forces are the attractive forces that exist between molecules

• In order of increasing strength, these are:
1. London dispersion forces.
2. Dipole Dipole interactions.
3. Hydrogen bonding.

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INTERMOLECULAR FORCES, BOILING POINT, AND MELTING POINT

What are the three intermolecular forces?

In order of increasing strength, these are:
1. London dispersion forces.
2. Dipole Dipole interactions.
3. Hydrogen bonding.

Hydrogen bonds are the strongest

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INTERMOLECULAR FORCES, BOILING POINT, AND MELTING POINT

What does the strength of the intermolecular forces determine?

• the strength of the intermolecular forces determines
- If a compound has a high or low melting point and boiling point
- if it is solid, liquid, or gas at a given temperature

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LONDON DISPERSION FORCES

What are London dispersion forces and why do they have weak interactions?

Review charges (✨) pg 36

London dispersion forces are very weak interactions due to the momentary changes in electron density in a molecule

• the change in electron density creates a temporary dipole

• the interaction between these temporary dimples constitutes London dispersion forces

• all covalent compounds exhibit, London dispersion forces

• the larger, the molecule, the larger, the attractive force, and the stronger the intermolecular forces

✨- more electron density in one region creates a partial negative charge (δ-)

✨- less electron density in one region creates a partial positive charge(δ+)

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DIPOLE-DIPOLE INTERACTIONS

What are dipole dipole interactions?

• dipole dipole interactions are the attractive forces between the permanent disciples of two polar molecules.

Pg 37

Formaldehyde

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Hydrogen Bonding

What is hydrogen bonding and when does it occur?

• hydrogen bonding occurs when a hydrogen atom bonded to O, N, or F is electrostatically attracted to an O, N, or F atom in another molecule

• hydrogen bonds are the strongest of the three types of intermolecular forces

📍📍📍 INTERMOLECULAR FORCES Out of the three intermolecular forces which has the strongest bonds?

Hydrogen bonds are the strongest of the three types of intermolecular forces

📍📍📍📍📍🌟 Intermolecular forces review Name the three intermolecular forces and determine whether their relative strength is weak or strong what they are exhibited by and give an example .

1. London dispersion Relative Strength: weak Exhibited by: all molecules Example: CH4, H2CO, H2O 2.Dipole- dipole Relative Strength: moderate ✨ Exhibited by: molecules with a net dipole Example: H2CO, H2O 3. Hydrogen bonding. Relative Strength: Exhibited by: Molecules with an O-H, N-H, or H-F bond Example: H2O

📍📍📍📍📍 INTERMOLECULAR FORCES BOILING POINT AND MELTING POINT What is the boiling point and the melting point? What happens to them when there is a strong intermolecular force? pg 41 for more info

1. The boiling point is the temperature at which a liquid is converted to the gas phase. 2. The melting point is the temperature at which a solid is converted to the liquid phase. ✨••• The stronger, the intermolecular forces, the higher the boiling point and melting point

💧💧💧💧💧 THE LIQUID STATE VAPOR PRESSURE What is evaporation and is it considered an endothermic or exothermic reaction? (Boiling hot water for too long)

• evaporation is the conversion of liquids into the gas phase • endothermic reaction -- it absorbs heat from the surroundings

💧💧💧💧💧 THE LIQUID STATE VAPOR PRESSURE What is condensation and is it an endothermic or exothermic reaction? (Water droplets forming on the outside of a cold glass on a warm day)

• condensation is the conversion of gases into the liquid phase • exothermic-- it gives off heat to the surroundings

💧💧💧💧💧 THE LIQUID STATE VAPOR PRESSURE What is vapor pressure? What are some facts about vapor pressure.

1. vapor pressure is the pressure exerted by gas molecules and equilibrium with the liquid phase 2. • vapor pressure increases with increasing temperature • the boiling point of liquid is the temperature temperature at which its vapor pressure = 760 mmHg • stronger than intermolecular forces, the lower the vapor pressure at a given temperature Pg 46

💧💧💧💧💧 THE LIQUID STATE VISCOSITY AND SURFACE TENSION What is viscosity?

• viscosity is a measure of a fluid's resistance to flow freely • a viscous liquid feels "thick" • compounds with strong intermolecular forces tend to be more viscous • substances, composed of a large molecules, tend to be more viscous 📍Any example of viscous compounds?📍

💧💧💧💧💧 THE LIQUID STATE VISCOSITY AND SURFACE TENSION What is surface tension? List facts Pg 49 video 📽️

• surface tension is a measure of the resistance of a liquid to spread out - The stronger the intermolecular forces, the stronger the surface molecules are pulled down toward the interior of a liquid and the higher the surface tension - Water has a very high surface tension because of its strong, intermolecular hydrogen bonding - when small objects seem to "float" on the surface of water, they are held up by the surface tension only.

🧊🧊🧊🧊🧊 THE SOLID STATE What two categories can a solid fall under ?

• a solid is one of the three states of matter, and can be categorized as either crystalline or amorphous ✨

🧊🧊🧊🧊🧊 THE SOLID STATE What is a crystalline solid?

• a crystalline solid has a regular arrangement of particles--atoms, molecules, or ions---with a repeating structure

🧊🧊🧊🧊🧊 THE SOLID STATE What is an amorphous solid? Pg 53 📽️

• an amorphous solid has no regular arrangement of its closely packed particles. - lacks atomic structure Glass rubber and some plastics • no regular arrangement of their particles • they can be formed when liquids cool too quickly for regular crystal formation • very large covalent molecules tend to form amorphous solids, because they can become folded and intertwined

🧊🧊🧊🧊🧊 THE SOLID STATE What are the four types of crystalline solids? Define them

1. Ionic solid: is composed of oppositely charged ions (NaCl) 2. Molecular solid: is composed of individual molecules, arranged regularly (H2O) 3. Network solid: is composed of a fast number of atoms, covalently bonded together (SiO2) 4. Metallic solid: a lattice of metal cations, surrounded by a cloud of e- that move freely (Cu)

🔥🔥🔥🔥🔥 SPECIFIC HEAT Specific Heat = Heat/ mass • ΔT = cal (or J)/ g • ΔT Pg 55 for Specific heat of substances

• The specific heat is the amount of heat energy (cal or J) needed to raise the temperature of 1 g of a substance by 1°C The larger the specific heat, the less its temperature will change when it absorbs a particular amount of heat energy.

🔥🔥🔥🔥🔥 Pg56-67 for 1. How to calculate the heat absorbed, given specific heat. 2. Pg 65 for Summary or Energy and Phase Changes

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