Chemistry mock weak points Flashcards
What ions are most likely to be aqueous
soluable compounds like NaCl, KNO3 and strong acids/bases
What ions are likely to not be aqeuous
insoluable ionic compounds eq CaCo3 and covalent compounds
What is an acid
Hydrogen donator/ protons
What is a base
Contains hydroxide ions and reacts neutralises Acids
What is an alkali
a base dissolved in a solution
What is first ionisation energy
energy require to remove one mole of an electron from 1 mole of gaseous atoms
What are the 3 factors that affect ionisation energy
Nuclear charge- increased pull from the nucleus makes it harder to remove an electron
atomic radius- the number of shells affects how far the valence electrons are from the nucleus attraction
shielding- the presence of shells of an atom weaken the affect of the nucleus attraction
What is the trend of first ionisation energy down a group
there are more shells despite increase nuclear attraction the valence electrons are further away therefore it decreases down the groupW
What is the trend of first ionisation energy across a period
The number of shells stays the same but nuclear charge increases so its harder to remove an electron therefore first ionisation energy increases
What are the two exceptions to first ionisation energy increase across the period
groups 2,3/ 5,6
2,3 this is due to the furtherest electron being in a P orbital compared to its prior being in an S, p orbitals have higher energy levels and therefore are easier to remove
5,6 the repulsion from both electrons being in the same orbital makes it easier for the electron to be removed
What is an induced DP DP interaction
random movement of electrons can cause a momentary DP of charge in atoms when then cause a other atoms to gain charges and be attracted to one another
What increases the strength of induced DP DP interactions
Larger molecules with more electrons have larger electron clouds as well as molecules with large surface area as they have large exposed electron clouds
What is a permanent DP interaction
The weak interaction between two polar molecules
What is a hydrogen bond
Hydrogen bonded to O,F,N have high cause for the molecule to become polar which can then bond to other similar molecules
Allotropes meaning
different forms of the same element
graphite
Hexagonal sheets with weak intermolecular bonds between the sheets, carbons each bonded to 3 others with a delocaised electron
Diamond
4 carbon bonds tetrahedral shape with a very high boiling point
Silicon
same structure as diamond 4 Si bonds which make up a lattice structure
Metallic bonding
Where metal atoms give up electrons to become delocalised positive atoms held together by delocalised electrons
How does melting/boiling point vary in metallic bonding
The amount of electrons per positive atom affects how strong the bonding is
What are the other properties of metallic bonding
Maliable- ions can slide over each other
Conductivity- delocalised electrons can carry charge
solubility- insoluble unless in liquids
Melting and boiling points in metals across a period
increases across a period as there are more delocalised electrons which make metallic bonding stronger
Melting and boiling points in giant covalent structures
very high due to the strong covalent bonds holding them together B,C and Si
Melting and boiling points in simple molecular structures
much lower due to being held together by only induced dp dp interactions. Larger molecules have higher electron clouds so have higher Bp S8 P4 Cl2
Reactivity down the group
As the energy require to remove an electron decreases down the group reactivty increases down the group
Group 2 Metal + Water
Metal hydroxide + hydrogen
metal hydroxide can dissolve in water to produce hydroxide ions which make strong alkaline solutions
Group 2 metals + Oxygen
Metal oxides
Group 2 metals + acids
Salt + hydrogen
Uses of group 2 metals
used in agriculture to neutralise acid soils
can also be used as antacids for acids in the stomach
What is the trend in reactivity down the group Halogens
Atomic radius increases as well as shielding this makes it harder to pull in an electron to from an ion so down the group halogens get less reactive
Displacement of halogens
More reactive halogens when displace a less reactive halogen from its solution
How to distinctly see halogens
Add mixture to organic solvent like hexane and shake a solvent layer containing the halogen will form on top
What colours do the halogens show
violet pink - iodine
orange red- bromine
yellow/green- chlorine
test for halides
Add Dilute acids eg HNO3 to test for other ions and then add silver nitrate
Chlorine white
bromine cream
iodine yellow
Halide solubility in NH3
Cl- dissolves in dilute
Br- dissolves in conc
I - doesn’t dissolve at all
Making bleach
2NaOH + Cl2 -> NAClO + NaCl + H20
Formation for Chlorate(I) ions
Cl2 + H20 reverisble HCl + HClO
HClO + H2O reversible CLO- + H3O
CLO is chlorate ion
Test for Carbonate
Add a dilute ass if it bubbles it is present
Test for sulfates
Add Ba+ ions eg Barium nitrate will form a white ppt
Test for amonia
Heat mixture under damp red litmus paper should turn blue
Standard enthalpy change of reaction
Enthalpy change when a reaction takes place in molar quantites of the equation in standard states under standard condtions
Standard enthalpy change of formation
enthalpy change 1 mole of a compound is formed from its elements under standard conditions in its standard states
enthalpy change of combustion
enthalpy change when 1 mole of a substance in burnt completely in oxygen in its standard states under standard conditions
standard enthalpy of neutralisation
Enthalpy change when acids and alkali react together to make 1 mole of water in standard states under standard conditions
What is hess’ law
The total change of a reaction is the same no matter the route taken
when calculating enthalpies
follow the arrow correct way and rearrange using the unkown value as X and making the 2 values equal to each other
What kind of reactions do alkenes undergo
electrophillic addition
How do alkenes produce alkanes
hydrogen with a nickel catalyst at 150 degrees
How to produce dihaloalkanes from alkenes
room temp and pressure no catalyst
test for unsaturation in alkenes
add bromine water should go from brown to colourless
how to make alcohol from alkene
Steam phosphoric catalyst 300degrees at 60/70 atm
subsitution alcohol their OH group with a halide
Conc H2SO4 at room temp
elimination of alcohol where a H and OH are removed to make an alkene
acid catalyst 170 degrees
Oxidation of primary alcohol to aldehyde
gently heat alcohol with potassium dichromate(VI) and sulfuric acid and distil oxidising agent also used
reflux with oxidising agent
Oxidation of secondary alcohol to make ketone
reflux the alcohol with acidified dichromate(VI) to make a ketone
How do haloalkanes react
nucleophilic substitution
Hydrolysis of haloalkanes
done with warm aqeous alkali or water
SHC equation
Q= mcΔT
Percentage uncertainty
uncertainty * number of times measure/ measure value *100
Pv = nrt units
P= Pa
V= M3 dm3/100
N= moles
R= 8.314
T= temperature(K degress +273)a
what are standard conditions
298K 100Kpa
What is average bond enthalpy
average enthalpy change when 1 mole of covalent bonds are broken in gaseous conditions
creation of ozone
O2-> 2o. in uv light
O2+O -> O3
chlorine radical fomation and attack ozone
CF2Cl2 -> CF2Cl2 + Cl.
Cl. + o3-> ClO + O2
ClO+O -> Cl. + o2
Other atoms attack ozone
R. + O3 -> RO. + O2
RO. + O. -> R. + 02
Which group takes priory in benzene ring
phenyl groups
What kind of reactions does benzene undergo
electrophillic substitution nucleophiles attracted to high electron density
Why is benzene stable and how does it react
Very stable ring so takes a very strong nucleophile to break the ring
What is the carrier for alkylation and acylation of phenols and regeneration
AlCl3
Alcl3 + H+ -> AlCl4
reaction bebtween Ch3Cl + AlCl3
Ch3Cl + AlCl3 -> AlCl4 + Ch3+
What is the halogen carrier for nitration of benzene
Concentrated Sulfuric acid
Reaction for nitration explain
Conc H2so4 Conc HNO3
H2SO4 + HNO3 -> HSO4- H2NO3
H2NO3 -> H2 + NO3
sulfuric acid is a stronger acid than HNO3 and gives a hydrogen to nitric acid froms an unstable compound which decomposes to form a nitronium ion
Aromatic, aliphatic and alicylic
Aromatic- contains benzene ring
Aliphatic- anything containing straight or cyclic carbon molecules thats not benzene
Alicylic- contain cyclic molecules eg cyclohexane but does not contain benzene
What are phenols
Benzene with an OH group which adds to the electron density so it makes it more reactive
weak acid partially dissociates in solution
What is the test for phenols
FeCl3 positive test is purple colour
Phenol + Base
Salt + water
Phenol + metal
Salt + hydrogen
Phenol + BR
tribromo phenol which decolourises br water
Electron donating phenol
OH and NH2 add electron density to the benzene ring which makes it easier to react, increases densities at 2,4 and 6
Electron withdrawing phenol
NO2 dont have p orbitals to add to the ring so removes electron density from 2,4 and 6 and directs to 5 and 3
