Gr11 Chem Exam - Unit 4

electronegativity

an atoms ability to attract electrons when bonded

3 type of bonds

polar covalent: unequal sharing of e- (0.4 < EN < 1.7)

non-polar covalent: equal sharing of e- (EN </= 0.4)

ionic: transfer of e- (EN >/= 1.7)

ways of representing polar covalent bonds

dipole arrows

partial charges

molecular dipole arrow (big ass arrow instead of tiny ones)

concentration

max amount of solute that can dissolve in a givne amount of solvent at a given temp

dissociation + dissociation equatino

pre-existing ions are seperated (occurs in ionic componds, ionic bases, anything that transfers electrons)

equation: KCl (s) —> K+ + Cl-

• no states

• so changing subscripts / balancing

ionization + ionization equation

new ions from reactants are created

(covalent compounds, covalent bases, acids, anything with shzring of electrons)

equation: (NH₄)₂SO₃(s) —> 2NH₄⁺ + SO₃^2-

• no states

• so changing subscripts / balancing

precipitate

solid formed duirng chemical reaction/decreased solubility

low solubility form of a solution

different types of intermolecular attraction

hydrogen bonding

ion-dipole forces

london dispersion

hydrogen bonding

polar moelcules

H + N/O/F

strongest force

ex: sugar + h2o

(only the lattice seperates not the molecule)

ion-dipole forces

ions + polar molecules

iondic compounds dissociate

ex: sakt + h2o

london dispersion

non-polar molecules + temp dipoles

weakest force

temp. dipoles

non-polar molecules with an unequal distribution of electrons

happens due to outide oppositely attractive force

intermolecular

between molecules

intramolecular

between atoms (coalent/ionci bonds)

examples fo insoluble substances

sand (SiO₂), chalk (CaCO₃), BaSO₄

types of solutions + examples

air (g)

alloys (s)

vinegar (l)

ocean water/rubbing alcohol (aq)

what does (aq) mean?

aqueous

soluble (can be dissolved well in water)

Types of concentration calculations

% mass by mass: c = (m solute / m solution) x 100%

% mass by volume: c = (m solute / v solution) x 100%

% volume by volume: c = (v solute / v solution) x 100%

-

very small concentration

c (ppm): (m solute / m soution) x 10^6

c (ppb): (m solute / m soution) x 10^9

-

UNITS

mass = g

volume = ml

ppm/ppb

-

Molar concentration

C = n solute / v solution

(mol/L)

equipment needed for preps of standard solutions

volumetric flask

volumetric pipet (can adjust volume)

graduated pipet (fixed volume)

procedure for preparing a solution from a solid solute

• solute in beaker

• add part of solvent to dissolve solute

• add solution into volumetric flask through a funnel

• rinse flask and funnel with distilled water to catch all of solute

• add remaining solvent

procedure for preparinf solutions by dilution

• original solution in beaker (concentration)

• add volume of original solution required into volumetric flask with pipet

• add remining solvent untill required volume

dilution calculations

ni = nf

CiVi = CfVf

standard solution

solution with known concentration

unsaturated

amount of solute in solution < solubility of solution

saturated

amount of solute in solution = solubility of solution

supersaturated

amount of solute in solution > solubility of solution

done by manipulation of substance through heat, crystals from

key word: dissolved

saturated with excess

amount of solute in solution > solubility of solution

key word: added

solubility

meausre of concentration

solubility: (Xg of solute/100g of h2o)

insolubility

(substance is insoluble)

substance with neglile solubility at SATP

low solubility

solubility < 0.1 mol/L

high solubility

solubility > 0.1 mol/L

what happens to the solubility of solids as temp. increases

solubility increases

dissovciation of solids is an endothermic process

what happens to the solubility of gasses as temp. increases

solubility decreases

dissolving of (g) to (l) is an endothermic process

le chateliers principle

explains how solubility of different substances changes with temp

if change is applied to a substance it will shift to counteract the change and reach equilibrium

total ionic equation

all (aq) ionic compounds and acids in dissociated form

net ionic equation

only neutral substance and ions involved in reactions are shown

spectator ion

entity that does not change and does not take part in chemical reaction

flame test dedects …

cations

sequential chemical analysis

based on double displacement reactions (formation of a precipitate and the filtering of said precipitate)

strong base

hydroxides from families 1 and 2 (-Be)

> 99% of solution dissociates

weak base

all other bases

< 50% of solution dissociates

strong acid

HCl, HBr, HI, HNO₃, H₂SO₄, HClO₄, HCO₃

> 99% substance ionizes

(>99%)

————>

weak acid

everything else

< 50% of solution ionizes

(<50%)

————>

Acid - Base properties (tests)

Conductivity

• both release ions when ionizing (acids) /dissociating (basses)

Phenolhalein

• Phenolhalein remains colourless in neutral

• Phenolhalein turns pink in base

• Phenolhalein turns cloudy in acid

Bromothymol Blue

• Bromothymol blue turns yellow in acid

• Bromothymol blue turns green in neutral

• Bromothymol blue stays blue in base

Litmus paper

• acids turn blue LP red

• Bases turn red LP blue

acid basses approx pH

acids = pH > 7 (1 × 10^-7 mol/L H+)

Basses = pH < 7 (1 × 10^-7 mol/L H+)

what is pH

measure of H+ concentration

pH calc

pH = -log (H+)

H+ calc

(H+) = 10^(-pH)

= 1.0 × 10^x mol/L

(H+) interchangable with C (moalrity)

what charge do products in enutralization reactions have?

0, they are neutral

single displacement with acids

acid + active metal —> H2(g) + ionic compouns

fizzing, bubbling, active metal reduced

double displacement with acids/basses precipitate colour

acid = white

base = brown

acids with CO3 prduced in reactions

basses = no reaction

acids = 2 ionization steps needed (diprotonic acid)

H₂CO₃ —> H₂O + CO₂

bubbling, fizzing

Arrhenius theory for acids and basses

Arrhenius Acids: substances that ionize in water to release a hydrogen ion

Arrhenius Bases: Ionic compounds that dissociate in water to release a hydroxide ion

tritatrion

method used to find unknown concentration of an acid/base by reacting it with a standard acid/base with a known volume untill neutralization reaction occurs

endpoint

when tritration is stopped

equivalence point

when solution is exactly neitralized

3 types of qualitative analysis

slution colour

flame colour

sequential analysis

7 steps in water treatment

primary treatment

• Screening: big solid particles filtered out

secondary treatment

• Aeration: water is sprayed/agitated with air to release dissolved gasses and to absrob o2

• Coagulation: chemicals mixed in water to group together tiny dirt particles

• Flocculation: water is mixed so inwanted sticky particles clump together

• Sedimentation: water stays still so dirt/clumps sink to bottom

teritairy treatment

• Filtration: water passes through porous material to capture any microscopic impurities

quartenary treatment

• Disinfection: disenfectant added to destrou any remaining bateria, viruses or parasites

whats the most important step

disinfection

dilution

lowering the concentration of a solutino by adding mroe solvent

how does diluting change affect the ph of acids and basses

acids: decreases H+ concentration, increases pH, less acidic

bases: decreases OH- oncentration, decreases pH, less basis

both values become closer and closer to 7

difference in pH vs difference in H+

1 diff in pH = 10x diff in (H+)