Chemistry - Unit 8 Test General Review

Comprehensive review of various concepts/formulas/conversions that may be useful to have well remembered according to the test overview and unit slideshow (not fun!!!)

Solids (Particle motion)

Particles vibrate

Liquids (Particle motion)

Particles slide past/against each other

Gases (Particle motion)

Particles move very quickly and freely of one another

Solids (IMFs)

Experiences the strongest IMFs

Gases (IMFs)

Experiences the weakest IMFs

Liquids (IMFs)

Experiences IMFs that are stronger than in gases, but weaker than in solids

Solids (Particle distance)

Particles are the closest together; they are packed very tightly together (rough explanation)

Liquids (Particle distance)

Particles are close to one another and have some distance from one another; more particle distance than solids but less than gases (rough explanation)

Gases (Particle distance)

Particles are the farthest apart and can be very far from each other (rough explanation)

Solids (V + S)

Definite/Fixed Volume and Shape

Liquids (V + S)

Fixed/Definite Volume and Indefinite Shape (assumes the shape of the container)

Gases (V + S)

Indefinite Volume and Indefinite Shape (assumes the shape of the container)

Solids (KE)

Lowest (average) kinetic energy when compared to all three states of matter

Gases (KE)

Highest (average) kinetic energy when compared to all three states of matter

Liquids (KE)

Higher (avg) kinetic energy than solids, lower (avg) kinetic energy than gases

Solids

Liquids

Gases

Image assumes an open container, must be adapted in a closed container

Gases

The **only** compressible state of matter (thereby meaning the **other two** states of matter are **not** compressible!)

Temperature

Average kinetic energy of all particles within a substance; measured with a thermometer

**Intra**molecular Forces

Occurs **within** a molecule; Ionic or Covalent; Chemical Reaction occurs when broken

**Inter**molecular Forces (IMFs)

Weak attractive force **between** molecules; London-Dispersion, Dipole-Dipole, Hydrogen Bond, Ion-Dipole; Physical Change occurs when broken

London-Dispersion Forces

(IMF) Exists in all substances; caused by an unequal distribution of electrons in a molecule or atom, creating a temporary instantaneous dipole at any given moment

Dipole-Dipole Forces

(IMF) **Only** present in **polar covalent** molecules; the unequal sharing of electrons create a permanent dipole which causes this IMF (positive ends are attracted to negative ends)

Hydrogen Bonding

(IMF) Special case of Dipole-Dipole Forces; only occurs when **H** is bonded to a **N**, **O,** or **F**

Ion-Dipole Forces

(IMF) **Only** occurs in mixtures with two different substances, one of which being an ion and the other being polar and covalent; caused by ions dissociating within a polar solvent so that cations are attracted to negative ends of the polar molecule and anions are attracted to positive ends of the polar molecule

Dispersion, Dipole-Dipole, H-Bond, Ion-Dipole

Order of IMFs from **weakest** to **strongest**

IMF Strength

Affected by the distance between particles (Inversely Proportional); Strength of charges (Electronegativity); Dispersion forces are affected by molar mass, easier to polarize when larger; Indirectly affected by temperature due to the Kinetic Molecular Theory

IMFs

Viscosity, cohesion, surface tension, and adhesion are caused by ____.

Kinetic Energy

1/2mv^2 (m = mass, v = velocity) → This pertains to the Kinetic Molecular Theory.

Solid

What does (A) indicate?

Melting/Freezing

What does (B) indicate?

Liquid

What does (C) indicate?

Vaporizing/Condensing

What does (D) indicate?

Gas

What does (E) indicate?

A, B, C, D, E

In which letters is the substance increasing in **energy** (both kinetic and potential)?

A, C, E

In which letters is the substance increasing in **kinetic energy**?

IMFs

During (B) and (D), since the line is flat, what is the energy used to overcome?

Liquid

What does (A) indicate?

Solid

What does (B) indicate?

Gas

What does (C) indicate?

Sublimation/Deposition Line

What does (C) indicate?

Triple Point

What does (A) indicate?

Melting/Freezing Line

What does (D) indicate?

Vaporization/Condensation Line

What does (B) indicate?

Critical Point

If the point is at the end of the Vaporization/Condensation line as it is with (B), what does the point also indicate?

Pressure/Temperature

In a phase change diagram, what are the two labels on the axes? (Y axis first, then X)

Endothermic

Requires energy input to make them happen (IMFs are being overcome)

Exothermic

Releases energy as they happen (IMFs are becoming significant)

Endothermic

Endothermic or Exothermic? (Melting, Vaporization, Sublimation)

Exothermic

Endothermic or Exothermic? (Freezing, Condensation, Deposition)

Boyle’s Law

(P1V1 = P2V2) At constant mass and temperature, the pressure and volume of a gas are **inversely proportional**.

Charles’ Law

(V1/T1 = V2/T2) At constant mass and pressure, the volume and absolute temperature (K) of a gas are **directly proportional**.

Gay-Lussac’s Law

(P1/T1 = P2/T2) At constant mass and volume, the pressure and absolute temperature (K) of a gas are **directly proportional**.

Combined Gas Law

(P1V1/T1 = P2V2/T2) → **Important formula to know**, it replaces knowing each of the three Gas Law formulas individually.

STP

Standard Temperature and Pressure → **1 atm** and **0 degrees C** (**273 K**)

Molar Volume

**At STP**, the volume occupied by **1 mol** **of gas** is **22.4 L**. → When doing Stoichiometry, 1 mol of gas **at STP** = 22.4 L

Ideal Gas Law

(PV = nRT) → **Important formula to know**, while there are other important uses, it also has to be used during Stoichiometry when you are **not** at **STP**.

R (atm)

(Universal Gas Constant) → R = 0.0821 L ⋅ atm/mol ⋅ K

R (kPa)

(Universal Gas Constant) → R = 8.315 L ⋅ kPa/mol ⋅ K

Ideal Gas

A gas which is behaving according to the Kinetic Molecular Theory → Allows for the Ideal Gas Law to be used. → Gas behavior is most ideal at low pressures, high temperatures, and in nonpolar atoms/molecules.

Real Gas

A gas which does not follow the Kinetic Molecular Theory, typically occurs when a gas gets close to condensing or turning into a solid. This happens at low temperatures or high pressure. → Unlike ideal gases, particles in a **real gas** have significant volume, have IMFs that attract each other, and have collisions that are inelastic (loss of KE).

Absolute Zero

The lowest possible temperature at which all molecular motion stops (KE = 0). → 0 K

Celsius to Kelvin

T (Celsius) + 273 = T (Kelvin) → Exact conversion factor, so use the amount of decimals of the given Celsius temperature for sig figs

atm to Pa

1 atm = 101,325 Pa (can be rounded to 101,300)

atm to kPa

1 atm = 101.325 kPa (can be rounded to 101.3)

atm to mmHg

1 atm = 760 mmHg

atm to Torr

1 atm = 760 Torr

atm to psi

1 atm = 14.7 psi