Chemistry Flashcards
What does rate of reactions depend on?
Amount of catalyst does not affect
Rate of reaction depends on moles : must calc mol if vol/ conc is changed
Format for oxidation reduction qns: oxidation state
- ___ is oxi/red as there is an incr/decr in OS, ___
- From ___ in ___ to ___ in ___
- Since there is incr/decr in OS, ___ is oxi/red
Format for oxidation reduction qns: electron transfer
- ___ is oxidised as
- ___ loses/ gains () electrons
- Thus, ___ is oxi/red
If oxi/red agent,
4. Repeat 1-3
5. Since ___ is oxi/red, ___ is an oxi/red agent
Disproportionation reaction
Same substance reduced and oxidised simultaneously in same chem reaction
ammonia chem formula
NH3
Methane chem formula
CH4
Solid DAM
Very closely packed
Orderly fixed positions
Vibrate
Liquid DAM
Closely packed
Not orderly, fixed positions
Slide around
Gas DAM
Far apart
Random arrange
Move freely in any direction; high speeds, occupies any available space
Kinetic particle theory
States all matter is made of tiny particles which are in continuous random motion
Factors affecting rate of diffusion
Temp: incr - more KE - move faster - faster rate of D
Molecular mass: greater - slower move - slower rate of D
Some uses of isotopes
Medical: iodine-131 treatment of thyroid disorder
Archeology: carbon-14 est. age of items containing carbon
Ionic structure
Giant ionic crystal lattice structure
Strong electrostatic forces of attraction between opp charged ions
Ionic physical properties: volatility, M&B pts, solubility, electrical conductivity
Cannot evap easily
High mbpts
Usually soluble in water, not in organic solvents
Solid cannot conduct, molten and aqueous can
Ans format for physical properties of bonds
- structure
- bond type
- attraction
- amt of energy
- physical property
Simple covalent physical properties: physical state, mbpts, volatility, solubility, elec conductivity
Liquids and gases
Low mbpts: weak van der waals forces
Evaporates easily
Not soluble in water, yes in organic compounds
Electrical conductivity: most do not
Giant covalent molecules physical properties
Mbpts, solubility, elec. conductivity
Very high- strong covalent bonds
Insoluble in both water and organic solvents
Does not conduct except graphite
Why does graphite conduct electricity
Only uses 3 valence electrons, leaving one free to move and carry neg charge
Diamond structure
Giant rigid tetrahedral structure. each C atom to 4 C atoms by strong covalent bonds
no free and mobile electrons to carry -ve elec charge
Graphite structure
Giant network of planar hexagonal ring layers
each C atom to 3 C atoms by strong covalent bonds : 1 free and mobile
Between each layer: weak intermolecular forces of attraction - can slide
Silicon dioxide
Silica, in sand
Giant rigid tetrahedral structure like diamond
1 Si to 4 O atoms
Metallic bonding structure
Giant metal lattice structure
Pos charged ions and delocalised, mobile valence electrons
Metallic bonding
Strong electrostatic force of attraction
Surrounding sea of delocalised mobile neg charged valence electrons and positively charged metal ions
Metals physical properties
Electrical conductivity
Heat conductivity
Density
Mbpt
Good conductors of electricity (sea)
good conductors of heat (Sea)
High density: orderly and rigid (packed tightly, oderly and rigid arrangement)
High mbpt (strong electrostatic forces of attraction)
Ductile (into string) and malleable (bend) (layers can slide without disrupting metal lattice)
Test for oxidising agent
Acidified potassium iodide : colourless to brown - formation of iodine from iodine ions via oxidation
Test for reducing agent
Acidified potassium mags are (VII) KMnO4 (aq)
Purple to colourless
Purple MnO4 ions reduced to colourless Mn2+
Solubility chlorides
Soluble except lead and silver
Solubility sulfates
Soluble except lead, calcium and barium
Copper does not react w this
Solubility carbonates
Insoluble except group 1, ammonium salts
Nitrates
Soluble
Hydroxides solubility
Insoluble except group 1, ammonium salts, first 2 grp 2, CaOH sparingly soluble
Precipitation
Insoluble (product) salts - metal nitrate + aq solution
Titration
Soluble group 1/ ammonium salts - metal OH/CO3 + acid
Both reactants soluble
Adding in excess
both reactants not soluble
PT: group 1 metals physical properties
- Soft alkali metals
- Low densities, mp,bp
- tarnishes rapidly in air
Group VII (halogens) elements
Halogens, need 1 electron
exists as diatomic covalent eg. Cl2
Very reactive, decr down group
Colour darkens down grp
Displacement reaction
where one element takes the place of another element in a compound (in the form of an aq solution)
Noble gases physical properties 5
- At stable octet / duplet configuration
- monatomic element
- colourless gases at rtp
- low mp bp (incr down, weak VDW forces incr w size)
- insoluble in water
Transition metals physical properties 4
siny and silvery
Good conductors of electricity
Hard and strong (sea, STRONGER bonds than grp 1-2)
High mbpts, high density compared to other metals
Disadvantages of pure metals
Soft and weak
May react with air and water / corrode easily
Alloy
Mixture of metal with one/ a few other elements
Benefit of alloys
Harder and stronger
Improves appearance
More resistant to corrosion
Lowering melting points
Reactivity series
Potassium
Sodium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Tin
Lead
Hydrogen
Copper
Silver
Good
Platinum
Metals and cold water
= metal hydroxide + h2
Usually very reactive metals eg, grp 1-2
Magnesium very slowly, below do not
Metals with steam
= metal oxide + h2
Magnesium reacts violently
Zinc and iron react
Below iron do not
Metals and dilute hcl
= salt and H2
Below hydrogen no
Lead reacts slowly but forms insoluble layer, prevents further reaction
Rust prevention
Surface prot
sacrificial prot
Benefits of recycling
Problems w recycling
Extraction req more energy than conserving
Less enviro problems
Can be more costly
Effort req from communities
Enviro issues
molecular mass diffusion ans format
both gases diffuse at DIFFERENT RATES towards each other. A is faster with a Mr of — than B with a Mr of — thus the gases meet to form —- closer to A.
melting solid to liquid
particles in solid VIBRATE AND MOVE FASTER when heated, GAIN KE, until sufficient energy to overcome inmcFOA holding them in their fixed positions
freezing liquid to solid
particles in liquid SLOW DOWN and KE DECREASES as energy is lost to surroundings as heat
particles settle into FIXED POSITIONS in an ORDERLY ARRANGEMENT forming a solid
change in state 3 stages (the one graph that goes _/–
- incr/decr temp, KE
- mixture: constant temp, overcome intmFOA
- gain enough energy to overcome inmcFOA. temp cont incr
boiling liquid to gas
particles in liquid MOVE FASTER when heated, gain KE until sufficient energy to COMPLETELY OVERCOME the intmFOA holding them tgt
particles FAR APART, move FREELY AND RANDOMLY in ALL DIRECTIONS, forming a gas
evaporation
- liquid changes to gas at temps below bp
- all temps
- only at surface of liquid
- volatile liquids (low bp) evap very quickly (bp usually just above rtp)
diff between evap and boiling 3
occurs at surface vs throught the liquid
at all temps vs only at bp
slow vs fast
condensation
- gas to liquid
- when water vapour touches cold surface
- when temp drops, lose KE, move slower, closer tgt
sublimation
- solid directly to gas
- particles at solid surface enough energy to break away as a gas
- heat energy taken in
eg. dry ice sublimes at -78C. also ammonium chloride and iodine
electron shell stability vs dist
incr dist to nucleus, decr energy level, incr stability
isotopes def
isotopes are atoms of the same element with the same number of protons but different number of neutrons, thus having a different relative atomic mass
calc isotopes relative atomic mass
(relative abundance of A x atomic mass of A) + (relative abundance of B x atomic mass of B) + …
element def
a pure substance, cannot be broken down into two or more simpler substances by chemical processes or elec
mixture vs compound 5
separation: physical, chemical
properties: same as components, diff from components
energy change in formation: no chem reaction, chem reaction takes place
composition: any proportion, fixed proportion by mass
mp&bp: variable, fixed
properties of graphite (3)
- high mp and bp
- good conductor of elec
- soft, slippery, fairly unreactive
dative bonds
(co-ordinate bond/dative covalent bond) both electrons come from same atom
periodic table groups (vertical)
- similar chem properties
- form compounds with similar formulae
- same number of valence electrons
periodic table across the period
- incr atomic no
- decr metallic character
- period: no of shells
- oxides change from basic to amphoteric to acidic
periodic table down the group
- incr atomic no
- incr in shell no
- properties change gradually
chemical properties transition metals 3
- form coloured COMPOUNDS and aq solutions
- variable valency and variable oxidation state eg Fe2+/Fe3+ in COMPOUNDS
- several are good catalysts eg iron in haber process, plat and rhodium in catalytic converter
catalysts
- used in small amounts
- remains chemically unchanged by end of reaction
- reusable
van der waals vs electrostatic vs intermolecular FOA
between covalent MOLECULES vs between ions and in metallic, between covalent i think or is it the same as van der waals
PT trends down grp 1
- density Incr down group
- mp/bp Decr down group (incr in no of elec shells, further away, weaker electrostatic forces of attraction)
- reactivity incr
- softness incr
grp 1 alkali metals react with water (Li, Na, K)
alkali metal + (cold) water -> metal hydroxide (sol, alkali in h2o) + H2 gas
- Li: reacts quickly. Li floats, no flame
- Na: reacts very quickly. molten sodium darts around water surface, yellow flame
- K: reacts violently. potassium melts, lilac flame
grp 1 alkali metals react with oxygen (Li, Na, K)
alkali metal + oxygen -> metal oxide
Li: red flame, white solid
Na: yellow flame, white solid
K: violently, lilac flame, white solid
PT: when halogen gains electron
forms halide ion
fluroine F + e- = fluoride F-
PT: Grp VII halogens down group
- mpbp incr (incr electrons, incr VDW forces betw molc)
- diff physical states at rtp: Fgas, Clgas, Brliquid, Isolid
- darken in colour
- less reactive
why low mp bp as a property format
(additional info may apply)
1. held tgt by — forces, which are strong/weak
2. large/small amt of heat energy req to OVERCOME these forces
PT: halogens chem properties
- react with most metals to form halides (salt compounds) : eg Na + Cl = NaCl
- more reactive will displace less reactive from aq halide (if change occurs, halogen more reactive than halogen in aq halide)
PT: Grp VII halogens physical properties
- low mp bp (molc held tgt with weak van der waals forces)
- do not conduct electricity (simple covalent)
PT: halogen displacement colours F,CL,BR,I
Cl2 + 2KI = 2 KCl + I2 (brown)
aq
F2: colourless
Cl2: pale yellow
Br2: reddish-brown
I2: brown
uses of noble gases (argon, helium, neon)
- argon: fill light bulbs, will not react with hot tungsten filament (provides inert atmosphere, prevents oxidation)
- helium: fill balloons, low density. lighter than air, heavier than H2, safer than H2 as does not burn
- neon: advertising strip lights (neon signs). range of colours by varying the mixture of noble gases. elec current passed thru for glow
transition metals aq colours 6, iron3, iron2, copper2, cobalt2, maganate7, dichromate7
iron3: yellow
iron2: (pale) green
copper2: blue
cobalt2: pink
maganate7: purple
dichromate7: orange
Salts definition
Produced when acid reacts with base.
Ionic compound formed when hydrogen ion in acid is replaced by metallic ion in a base or ammonium ion in aq ammonia
How to determine salt prep method
Soluble? No: precipitation
Both og mats sol in water? No: excess Yes: titration
Salts: Precipitation steps 4
- Add excess sol with anion to sol with cation (metal nitrate)
- Filter to obtain ppt (insol salt)
- Wash with distilled water to remove contaminants
- Leave ppt in cool dry place to dry
Salts: titration steps 8
A
1. Fill burearte with dilute acid. Note initial reading (V1)
2. Pipe the 25.0cm3 of alkali into con. flask
3. Add 1-2 drops of indicator eg methyl orange, sol turns yellow
4. Slowly add dilute acid until one drop causes the solution to change colour (end pt)
5. Stop adding hcl, record final reading (V2)
B
1. Pipette 25.0cm3 of alkali into con. flask
2. Add vol of acid req (V2-V1)
3. Allow salt sol to cool and crystallise
(NaCl: heat to dryness)
Salts: Reacting dilute acid w excess steps 7
- React excess metal with dilute acid. Stir until no more dissolved, effervescence stops
- Filter to remove excess unreacted metal. Filtrate is salt solution
- Heat salt solution to half vol to obtain sat. solution (glass rod test)
- Allow sat. solution to cool and crystallise
- Filter to obtain crystals
- Wash with distilled water (remove contaminants)
- Pat dry with filter paper
Why use excess reactant when adding in excess salt prep
Ensures all acid is used up, leaves no acid to contaminate salt solution
Why must the reactant be insoluble in water when adding in excess salt prep
Allows the excess reactant to be filtered from salt solution
Adding in excess salt prep using metal vs using metal carbonate
Metal carbonate used for moderately reactive metals. Some metals too reactive or too unreactive
What dries acidic gases
Conc sulfuric acid
What dries neutral gases
Calcium chloride
What dries alkaline gases
Quicklime
Tests for purity
Melting/boiling point: impurities lower mp raise bp
Paper chromatography
Mixture mp and bp
Melt over a range of temperatures
Separation of solid and liquid mixtures
- filtration
- evap to dryness
- crystallisation
Separation of solid and solid mixtures
- sublimation
- magnet
Separate liquid and liquid
Distillation/fractional, separating funnel, chromatography
What is sprayed in paper chromatography to show colourless compounds
Locating agent
Rf value calc
New position / solvent front
Catalytic cracking of alkanes products and conditions
Alkenes + Smaller alkanes +/or H2
600 degrees, catalyst Al2O3 or SiO2 aluminium oxide or silicon dioxide
Combustion of alkenes products
Co2 + h2o STEAM (g)
Hydrogenation of alkenes conditions
Forming alkanes
200 degrees, nickel catalyst
Hydration of alkenes conditions
Reaction with steam to form alcohol
H3PO4 (phosphoric) acid as catalyst + 300 degrees + 60 atm
Addition polymerisation of alkenes conditions
200 degrees, 1000 atm, catalyst
only for alkenes
Naming convention of polymers
poly(ethene)
Oxidation of alcohols products and conditions
Forms carboxylic acids
Oxidising agents : acidified potassium manganate (VII) (same as test for reducing!) or acidified potassium dichromate (VI)
Equation: when gas use O2, when agent/solution write 2[O]
Esterification of carboxylic acids conditions
Condensation reaction
Conc sulfuric acid catalyst , reflux conditions: vertical condenser ensures vaporised alcohol condensed back to prevent loss
Naming esters
Alcohol = alkyl
Carboxylic = oate
Macromolecule def
A very large molecule made from many small repeat units joined together by covalent bonds
gas collection methods 4
- displacement of water = insol or slightly sol = H,O,CO2
- downward delivery = gases denser than air & sol = Cl , HCl (heavier than N2)
- upward delivery = NH3
- gas syringe = can measure vol
quant.a : CO2 vs SO2 test
co2: Pass thru limewater to become milky white and has no colour change in acidified potassium manganate (VII)
SO2: Turns purple to colourless in acidified potassium manganate(VII)
NH4 +
in NaOH and NH3
NH3 gas evolves
no reaction
Ca 2+
in NaOH and NH3
White precipitate, insoluble in excess
No precipitate
Zn 2+,Al 3+,Pb 2+
in NaOH and NH3
White precipitate, soluble in excess NaOH to form colourless solution
Zn: white precipitate soluble in excess to form colourless solution
Al/Pb: Insoluble in excess
Cu 2+
in NaOH and NH3
Light blue precipitate thats insoluble in excess
Light blue precipitate thats soluble in excess to form a deep blue solution
Fe2+
in NaOH and NH3
Green precipitate thats insoluble in excess
Green precipitate thats insoluble in excess
Fe3+
in NaOH and NH3
Reddish brown precipitate thats insoluble in excess
Reddish brown precipitate thats insoluble in excess
Co3 -
test and observation
Add dilute HCl and pass gas evolved into limewater
Effervescence is observed and gas evolved forms a white precipitate (CO2)
No3 -
test and observation
Add aq NaOH and aluminium
Effervescence and NH3 and turns moist litmus red to blue
So4 2-
test and observation
Add dilute nitric acid and barium nitrate
White precipitate of barium sulfate
Cl -
test and observation
Add dilute nitric acid and silver nitrate
White precipitate of silver chloride
I -
test and observation
Add dilute nitric acid and silver nitrate
Yellow precipitate of silver iodide
oxidation
gains oxygen(O),
loses hydrogen(H),
loses electrons
gains in oxidation state. (Oxidation charge is the ionic charge),
reduction
loses O,
gains H,
gains electrons
reduces oxidation state
oxidising and reducing agents
Oxidising agents = causes other substances to be oxidised and gets reduced itself
Reducing agents = causes other substances to be reduced and gets oxidized itself
oxidising agents examples
Halogens
Concentrated H2SO4
Nitric acid
Oxygen
Potassium manganate (VII)
Potassium dichromate (VI)
Hydrogen peroxide
reducing agents examples
Carbon
Carbon monoxide
Hydrogen
Hydrogen sulfide
Metals
Potassium iodide
Sulfur dioxide
Ammonia
Test for oxidising agent
acidified potassium iodide KI(aq)
colourless solution to brown due to the formation of iodine from iodide ions via oxidation.
Test for reducing agent (2)
acidified potassium manganate(VII) KMnO4 (aq)
purple solution to colourless as the purple MnO4 - ions are reduced into colourless Mn 2+ ions.
acidified potassium dichromate(VI)
K2Cr2O7 (aq) turns the orange solution to green as the orange Cr2O7 2- ions are reduced to green Cr 3+ ions.
Disproportionation reaction
one reactant undergoes reduction and oxidation simultaneously. (redox is one ox one red)
Reaction of carboxylic acids with metals/carbonates/bases
cation should always be written behind the anion,
for example ethanoic acid reacts with magnesium; 2CH3COOH (aq)+ Mg(s) → (CH3COO)2Mg (aq) + H2 (g), forms magnesium ethanoate + H2
general formula of carboxylic acids
general formula = CnH2n+1COOH
Isomerism in alcohol (naming)
propan-1-ol= functional group attached to the 1st C atom ( can be 1st C atom from right to left, or left to right.)
Combustion of alcohol
CO2 + water vapour, flame is clean with no soot
fermentation of alcohols
microorganisms like yeast act on carbohydrates (glucose) to produce ethanol and CO2, conditions = anaerobic environment + presence of yeast + 37 degrees
Alcohol obtained is dilute, as yeast denatures when concentration of ethanol is too high
Oxygen shouldn’t be present, or it will oxidise into ethanoic acid (sour taste)
uses of ethanol
alcoholic drinks, solvent, paints, perfumes, fuels, vinegar
alkenes formula
C=C bond, unsaturated hydrocarbons with formula CnH2n
alkanes or alkenes more reactive why
Alkenes are more reactive than alkanes due to double bond, through addition unsaturated (alkene) becomes saturated (alkane)
Bromination
used to test for presence of alkenes, reddish brown aqueous bromine decolourises instantly into a colourless solution in presence of alkenes (C=C)
alkanes general formula
Cn H2n+2, with no functional groups, saturated
change in physical properties down the alkane series
↑mp + bp, : molecular size↑ = ↑ strong intermolecular forces of attraction, due to increase in relative atomic mass (Mr)
↑density,
↑r by 14 due to gain of CH2,
↑viscosity, : ↑stronger intermolecular forces of attraction = ↑difficulty in flowing
↓flammability : increase in Mr results in percentage of carbon present to increase = more O2 for combustion, so it produces smoky flames due to incomplete combustion (soot)
Isomerism
compounds with same molecular formula but different structural formula
substitution in alkanes
alkanes react with chlorine/ bromine
UNDER UV LIGHT
1 hydrogen gets replaced by chlorine/ bromine
hydrocarbon naming prefix
meth- 1
eth- 2
prop- 3
but- 4
pent- 5
hex- 6
hept- 7
oct- 8
non- 9
dec- 10
petroleum tower
Good (petroleum Gas)
Parents (Petroleum)
No (Naptha)
Kids (Kerosene)
Do (Diesel)
Love (Lubricating oil)
Babies (Bitumen)
sources of fuel: storage and pollution (3)
Natural gas : Methane CH4
Stored in big spaces in gas but can be liquefied easily, can flow through pipes easily
Almost no pollutants as no soot or SO2 produced
Petroleum : Hydrocarbons (alkanes)
Stored and transported easily by tankers, flow easily
Some soot and SO2 produced = moderate
Coal: carbon C
Not easily stored or transported but takes up less space when stored
Extremely = large amounts of soot and SO2 produced
Source of crude oil/ petroleum
- dead creatures in the sea fall to the sea bed, decomposed, eventually producing petroleum and natural gas was found on top of petroleum
- Biogas is produced when organic matter is allowed to decay in the absence of air ( 50% CH4)
Fractional distillation of petroleum (mixture of hydrocarbons) procedure
petroleum is first vapourised, rises in the tall fractionating column, where the top of the column is cooler than the bottom, and thus condenses.
Fractions with lower bp condense near the top of the column , higher bp condense near bottom of the column ( ↑size of molecule MR = ↑intermolecular force)
Petroleum contains more heavier and less useful hydrocarbons, and thus these can be broken down via catalytic cracking.
fd of petroleum products uses
Fuels = petroleum gas, petrol, gasoline, kerosene, paraffin, diesel oil
Feedstock for petrochemical industry = naphtha
Lubricating machines/ wax/ polishing = lubricating oil
Paving road surfaces = bitumen/ asphalt
issues related to petroleum
Burning of fuel = pollution + global warming
Non renewable, need to be conserved
Reduce consumption by using public transport/ using differing sources such as solar/ nuclear energy ( plutonium/ uranium but risk = harmful leaking radiation)
manufacture of sulfuric acid
manufacture of sulfuric acid by burning it in oxygen to form sulfur dioxide then sulfur trioxide and is then dissolved in sulfuric acid to form oleum (H2S2O7), then water is added to form sulfuric acid
Uses of sulfuric acid
manufacturing of fertilisers such as ammonium sulfate and dilute sulfuric acid is used in car batteries to release energy.
pH readings explain
pH = The concentration of H+ ions increases as the pH meter decreases while the concentration of OH- ions increases as the pH meter increases (7 = neutral)
Formula = -log( concentration of H+ ions)
alloys stronger why
Alloys are stronger and harder than pure metals as the atoms of different metals have different sizes, resulting in the disruption of the orderly rigid layers of atoms in the pure metal, making it more difficult for the layers to slide over one another.
metals with water and steam (more reactive than H)
Metals + water = hydroxides + H2
magnesium reacts very slowly w cold water and other metals below magnesium dont react with cold water at all
Metals + steam = oxides + H2
metals below iron like lead, copper and silver do not react steam at all
alloys reasons 4
- harder and stronger
- improve appearnace
- more resistant to corrosion (layer of oxide)
- lowers MP
