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