APSC 183 (Matter Energy II) Final Prep

Plasma

Gaseous state of matter containing a significant amount of electrically charged particles.

Elements

Pure substances that cannot be broken down into other substances.

Compounds

Pure substances that are composed of two or more pure substances.

Mixture

Composed of two or more types of matter, separatable by physical changes.

Heterogenous mixture

Mixture’s composition varies from point to point.

Homogenous mixture

Mixture’s composition is chemically and visually uniform.

Physical properties

Characteristic that doesn’t involve its chemical composition.

Examples:

• State of matter

• Color

• Malleability

• Energy

Chemical properties

Characteristics that involve its chemical composition.

Examples:

• Flammability

• Taste

• Smell

• Chemical Bonds

Extensive property

Property depends on amount of matter present.

Intensive property

Property does not depend on amount of matter present.

Unit prefix: T

Tera, 10^12

Unit prefix: G

Giga, 10^9

Unit prefix: M

Mega, 10^6

Unit prefix: k

Kilo, 10^3

Unit prefix: m

Milli, 10^-3

Unit prefix: µ

Micro, 10^-6

Unit prefix: n

Nano, 10^-9

Unit prefix: p

Pico, 10^-12

Molecular formula

Actual whole-number ratio of elements in a compound.

Empirical formula

Smallest possible whole-number ratio of elements in a compound.

Solvent

Component in a solution with the significantly highest concentration.

Solute

Component in a solution with a lower concentration compared to the solvent.

Diffusion

Transportation of materials by random motion.

Examples:

• Food coloring in water

• Yes I would like more salt diffusing into my soup please

• Who tf farted I can smell it from here

Brownian motion

Term for the random movement of small particles in fluids (gas and liquids).

Characteristics affecting diffusion (for speed)

• Temperature of the system

• Size of molecules

• Composition of molecules

Fick’s first law

Determines flux of matter due to the change in concentration.

Variables:

• J: Flux

• D: Diffusion coefficient

• C: Concentration/partial pressure

• x: Distance

Henry’s law

Determines the solubility of gasses at equilibrium.

Effusion

Escape of molecules through small holes or porous materials.

Graham’s Law

Relates the ratio of effusion rate to the molar masses of each molecule in interest.

Reaction quotient

Ratio of only gas and aqueous products to reactants (products over reactants), shown as Q.

Equilibrium constant

The value of Q when equilibrium is achieved, displayed as “K”.

Homogenous equilibrium

At equilibrium, all reactants and products are in the same state of matter.

Heterogenous equilibrium

At equilibrium, all reactants and products will be in one or more different states of matter.

ICE table

For equilibrium calculations, where Initial, change in concentration, and concentration at equilibrium are recorded into a table.

Le Chatelier’s principle

When a chemical system at equilibrium is disturbed, the system will counteract the disturbance to return to equilibrium.

Catalysts (and its affect on equilibrium)

3 key aspects:

1. Takes part in the reaction

2. Speeds up the rate of reaction (by lowering the activation energy required, suppressing side reactions, or forming intermediates to increase rate-limiting step(s)).

3. Returns to original form (basically a spectator).

Does not impact which direction the equilibrium shifts.

Saturated solution

The quantity of solvent in solute is at the perfect ratio, where adding more will form precipitation.

Solubility

How "dissolvable” a solvent is in a solute. Lower solubility means less is dissolved.

Precipitate

Only the insoluble solid(s) that forms from aqueous compounds reacting.

Bronsted-Lowry acids

Donates a proton to other substances, turns into a conjugate base.

Bronsted-Lowry bases

Accepts a proton from other substances, turns into a conjugate acid.

Acid and base ionization

Literally just when either an acid/base itself reacts with water.

Amphoteric species

A species that can both accept and donate a proton (Can switch between being an acid and base).

Water autoionization

Where at 25°C, the equilibrium constant of water = 1.0 × 10^(-14), aka K_w.

In pure water, concentration of hydroxide and hydronium are equal here.

Strong acids and bases

Will completely dissociate in water, therefore has no calculable reactant quotient.

Weak acids and bases

Will not completely dissociate in water, therefore it’s reactant quotient, K_a or K_b, can be calculated.

Hydrolysis of salts

When salts (neutral species) “hydrolyze” in water to create basic, acidic, or neutral solutions.

Polyprotic acids

Acids that contain more than one ionizable proton.

Examples:

• Diprotic with two ionizable protons

• Triprotic with three ionizable protons

Each ionizable proton is a step themselves. (Etc triprotic will have first ionization, second ionization, and third ionization)

Monoprotic acids

Acids that only contain one ionizable proton.

Buffer solutions

Solution of weak acid-base pairs, stabilizing the pH of the solution (added strong acids/bases are converted into weak ones).

They also have certain buffer capacities until pH fucking explodes and skyrockets (titration jumpscare).

Most effective when [base]:[acid] = 1.

Henderson-Hasselbalch equation

Calculates the pH of buffer solution with the concentration of the weak acid and its conjugate base.

Equivalence point

When the moles of hydronium = hydroxide.

EP for adding in acidic salt means pH < 7, basic salt pH > 7.

Reaction rates (+factors that affect it)

Change in something over time and will always be a positive value.

Factors that affect rate:

1. Chemical nature of reaction

2. Physical state of reactants (solid, powder, etc.)

3. Concentration of reactants

4. System temperature

5. Catalyst presence

Rate constant

“k” is used in reaction rate calculation and is specific to different reactions at different specific temperatures.

Half-life

“t_1/2” is the time it takes for one half of reactant to be consumed.

Lifetime of a reaction

“𝜏” is time it takes for reactant concentration to decrease to 1/e of starting concentration.

Collision theory

3 conditions for a reaction to occur:

1. Reaction rate must be proportional to collisions over time

2. Molecule geometry must be correct

3. Adequate kinetic energy (activation energy) to react

Transition state

State when adequate activation energy is achieved for reaction to proceed on a energy vs reaction graph.

Activated complex forms here as well.

Change in enthalpy

Defined as H, the sum of a system’s internal energy U and the product of pressure P times volume V.

Also the difference in energy between reactants and products, known as “ΔH”

Arrhenius equation

Calculates the k value with the following:

• A, how often collisions occur with correct molecular orientation (aka frequency factor)

• T, absolute temperature of system

• E_a, activation energy of reaction

Intermediates

Species produced in one step and then consumed in the next during chemical reactions (don’t show up in overall equation).

Rate-limiting step

One step in a multi-step reaction that’s significantly slower than the rest.

Temperature of system required for multi-step reaction

Less than 225°C, greater would be one step

Thermochemistry

The study of chemical reactions and the absorption/release of heat.

First law of thermodynamics

Energy can be converted, but never created nor destroyed.

Formula relates internal energy U to the sum of the heat, q, and work done, w, by the system.

q_p in enthalpy

Equals the change in enthalpy, is the heat gained or lost by system at constant pressure times changing volume.

Standard enthalpy of formation

The enthalpy change for a reaction, 𝚫H°_f, is when exactly one mole of pure substance in the products is formed.

Hess’s law

If a process can be written as the sum of several processes, the total enthalpy change equals the sum of all enthalpy changes in each step.

Redox reactions

Type of reaction involving the transfer of electrons between chemical species, usually the transfer of electrons from an oxidized atom to a reduced atom.

Oxidation reaction

Type of redox reaction, is when an atom loses electrons.

Reduction reaction

Type of redox reaction, is when an atom gains electrons.

Oxidation number

Literally just the charge of a species as an ion.

Half reaction method

For balancing redox equations by looking at the change of electrons from individual reactant elements to products.

Galvanic cells

A device that takes energy released in a redox reaction and is able to turn it into electrical work.

The transfer of electrons goes through an external circuit that separates the reactants.

Components:

• Two solutions

• Anode for oxidation

• Cathode for reduction

• Salt bridge to maintain charge balance

Cell potential

E_cell is the potential difference between the cathode and anode.

Standard cell potential

E°_cell is cell potential under the 3 standard conditions:

• 1M concentrations

• 1 bar pressure

• 298K

Standard hydrogen electrode

AKA “SHE”, used as universal reference for cell potential measurements, assigning a 0V potential.

Equation: 2H + 2e^- → H₂

Gibbs “free” energy

G, determines whether or not a process is spontaneous by combining enthalpy H and entropy S.