Chemistry Q2

completes honors chemistry high school level course; continuation of chemistry Q1 knowt

Gases

Gases

state of matter with unique characteristics that are dependant on surrounding conditions

Kinetic Molecular theory

says that all matter consists of tiny particles that are in constant motion; particles within a gas are considered to be small, hard, and spherical with an insignificant amount of volume; motion of gas particles is rapid, constant, and random; collisions between gas particles are perfectly elastic

general characteristics of gases

gas particles have insignificant volume; particles are far apart; particles are in rapid, random, and constant motion; particles line up/travel in straight lines; gas particles continue to spread into given space (atmosphere); collisions between gas particles are perfectly elastic

the theory that helps explain gas pressure

kinetic molecular theory

equation for pressure

pressure = force/area

gas pressure

the result of billions of rapidly moving gas particles colliding with an object

atmospheric pressure

pressure created by the earth’s gravitational pull on the gases in our atmosphere

barometer

device used to measure atmospheric pressure

Pascal (measurement, not the chameleon)

SI unit of pressure

One standard atmosphere (atm)

atmospheric pressure at sea level

the conversion from atm → mHg → kPa

1 atm = 760 mHg = 101.3 kPa

Dalton found this fact while examining properties of gases

each gas exerts its own independent pressure

Dalton’s law of partial pressure

states that the total pressure of a mixture of gases is the sum of the pressure of the individual gases; P₁+ P₂+ P₃ = P total

4 most important properties of gases

Volume (V), pressure (P), amount of gas (n), temperature (T)

Boyle’s law

establishes relationship between pressure and volume

what happens to pressure according to Boyle’s law when volume goes down

pressure goes up

what happens to volume according to Boyle’s law when pressure goes down

it can be assumed that volume has increased

Equation for Boyle’s law

P₁V₁ = P₂V₂

Charles’ law

establishes relationship between volume and temperature

According to Charles’ law, if temperature increases this happens to the volume

volume increases

equation for Charles’ law

V1/T1 = V2/T2

Kelvin Scale

Temperature measurement with an absolute zero

conversion equation from Celsius to Kelvin

K = C + 273 (C=Degrees Celsius given)

conversion equation from Fahrenheit to Kelvin

K = (y °F – 32) ÷ 1.8 + 273.15

Gay Lussac’s law

establishes connection between pressure and temperature

according to Gay Lussac’s law, this happens to pressure when temperature is increased

pressure also increases

Avogadro’s law

establishes the relationship between volume and amount of gas

According to Avogadro’s law, this happens to the amount of gas when the volume is increased

the amount of gas also increases

the unit the amount of gas is written in

Moles (6.02×10²³)

Combined gas law

allows derision any of the simple gas laws by removing the variable that is constant

combined gas law equation

P1*V1/T1 = P2*V2/T2

how to know it is a combined gas law problem

if the problem gives change in values or two scenarios

Ideal gas law

connects gas amount to other variables

Ideal gas law equation

PV = nRT

What is the universal gas constant (value)

0.082 atm.L/mole.K or 8.314 kPa.L/mole.K

Substance

has definite composition; only used to refer to something that is pure and defined

mixture

has varying composition of more than one thing; broken down into two categories: heterogenous and homogenous

Heterogenous mixture

you can see the pieces of the mixture; substance is not uniform throughout; ex.: lava lamp

homogenous mixture

cannot see different substances in the mixture; also known as a solution; composition is the same throughout; ex.: food dye mixed into water

solute

thing being dissolved

solvent

thing doing the dissolving

the way you can tell which thing is the solvent

the thing that there is more of is the solvent; it is usually liquid

the state of matter that solutions can be

solid, liquid, or gas

aqueous solution

a solution where the solute is dissolved in water

things that can be considered a solute

atoms, ions, or molecules

non-polar solvents will dissolve this

non-polar compounds

polar things will dissolve these

polar things

reasons that water is a common solvent

it is polar, which give it unique properties like surface tension, high boiling point, etc.; strong attraction between water molecules allow it to pull apart lots of ionic and polar compounds; when attraction between ions is stronger than the attraction of water molecules, you end up with a solid

solubility

how much solute dissolves in a certain amt. of time

solubility of an insoluble compound

less than 0.1g/100ml

temperature affects these

solubility of a solid, liquid, or gas

pressure affects this

solubility of a gas

an increase in temperature does this to the solubility of solids and liquids

increases solubility of a solid or liquid

this helps solvent particles to dissolve quicker

increased movement (juggling)

an increase in temperature will do this to gas solubility

decrease it; increased energy of gas particles allows them to escape quicker

an increase of gas pressure will do this to the solubility of gas

increase it; gas particles are pushing down on the solution, holding the gas in place

saturated solution

contains max amt. of solute for a given amt. of solvent at a given temperature and pressure

unsaturated solution

contains less solute than a saturated solution

this happens with the process of dissolution when saturation is reached

dissolution doesn’t stop; the rate of dissolution and re-crystalization are the same, so the total amount of solute stays constant

supersaturated solution

contains more solute than it can theoretically hold at that temperature

the factors that affect the rate of dissolution

stirring, temperature, surface area of the dissolving particles

why stirring increases the rate of dissolution

the agitation constantly brings new solvent in contact with the solute

why temperature increases the rate of dissolution

it increases the speed of solvent particles

why increased surface area increases rate of dissolution

increased surface area allows greater solvent/solute interactions

concentration

measures how much solute is in a solution; a ratio of solute to solvent

percent concentration by volume equation

%(v/v) = (volume of solute / volume of solution) x 100

percent concentration by mass equation

% (w/w) = (mass solute / mass solution) x 100

Molarity equation

moles solute / liters solution

how to find molarity of a SOLID x LIQUID mixture

question must state final measure of molarity, otherwise assume that no change/insignificant change has occurred and keep the liquid number the same as before

molality

accounts for concentration change due to volume change of a liquid

molality equation

moles of solute / Kg solvent

dilution

adding the required amount of extra solvent to a concentrated solution to reach desired concentration

dilution equation

M1V1 = M2V2 (M1 & V1 amounts taken from amount removed from stock concentration)

5 general reaction types

combination, single-replacement, double-replacement, decomposition, combustion

Dark room experimentation

no clue what will happen in experiment

combination reaction

2 or more substances combine to form one new substance or product; can be just elements, can be compounds, can be element + compound; always has ONLY ONE PRODUCT

Combination reaction example

2Mg + O₂ →2MgO

Decomposition reaction

single compound breaks down/decomposes; kind of reverse combination reaction; priestly used it to separate mercury and oxygen from mercuric oxide; often see something written above arrow like heat or catalyst

meaning of ‘△’ when it’s over an arrow in a reaction

heat

why heat or catalysts are often used in decomposition reactions

because the thing won’t break unless it has a reason to; it already formed because it ‘wanted’ to, so with no change it will stay together

the elements that are diatomics

Hydrogen (H), Nitrogen (N), Fluorine (F), Oxygen (O), Iodine (I), Chlorine (Cl), Bromine (Br)

Pneumonic to remember diatomics

Have no fear of ice cold beer (H, N, F, O, I, Cl, Br)

Decomposition reactions only result in these

elements

decomposition example

2HI → H₂ + I₂

combustion reaction

element compound reacts with oxygen, often producing CO₂, water, and energy in the form of heat and light (burning)

combustion reaction example

CH₄+ 2O₂ → CO₂ + H₂O

single replacement reaction

one element replaces a second element in a compound; an element + an ionic compound; swap thing on outside which is unstable with more stable thing on inside; will only occur if the outside element is more reactive than the element in the compound

activity series

lists metals in order of decreasing reactivity; can be used to predict if a single replacement reaction will occur

will this reaction happen?: Ag + CaBr₂

no, because silver is less reactive than calcium

Will this reaction happen?: F₂ + CaBr₂ → Br₂ + CaF₂

yes, because fluorine is more reactive than bromine

double replacement reaction

positive ions exchanged between two compounds; only way to get ionic compounds to react is to spread them out by dissolving them in water; **for this class ** the product has to have at least one solid

Double replacement reaction example

K₂CO_{3 (aq)} + BaCl_{2 (aq)} → 2KCL_(aq) + BaCO_{3 (s)}

when a double replacement reaction is considered to have happened

when a compound becomes insoluble due to a very strong attraction between the compounds

Liquids on the periodic table

Hg, Br₂

Gases on the periodic table

N_2, O_2, F_{2 ,}Cl₂

ionic compounds in a reaction equation

solid with less water present than aqueous

for covalent compounds in a reaction equation

have to be told state of matter

stochiometry

how we relate amounts of reactants & products to each other using a balanced equation; manipulating chemical formulas

1 mole

6.02 × 10²³

1 gram (in amu)

6.02 × 10²³ amu