P1 MISTAKES Flashcards
which of the following observations provides evidence that matter is composed of atoms?
A. line emission spectra of hydrogen produces 4 visible lines
B. NaCl is soluble in water and conducts electricity in aq state
C. water is liquid at RTP, but hydrogen sulfide and hydrogen slenide are gases
D. 12g of carbon combines with either 16 or 32 g of oxygen but never any other ratio
D
which aqueous solutions would have a different wavelength of max absorbance from 0.10 mol/dm3 FeSO4?
1. 0.01 mol/dm3 FeSO4
2. 0.10 mol/dm3 Fe2(SO4)3
3. 0.10 mol/dm3 FeSCN2+
2 and 3
they arent FeSO4???
which substance exhibits only London forces between molecules?
A. PF5
B. SF4
C. SO2
4. XeO2
A
which of these have positive enthalphy changes?
1. atomisation
2. ionisation
3. hydration
1 and 2
slow step requires the ____ potential energy
MOST
which factor is dependent on temperature?
a. activation energy
b. pre-exponential factor
c. rate constant
d. gas constant
C
in a equaiton where the forward reaction forms gas, in order to get more of the product, ________ the volume of the reaction vessel
increase
when you have the system 2A <==> B + 3C at equilibrium, whats the equilibrium constant?
[B][C]^3
/
[A]^2
which of the following are homogenous mixtures?
1. aq solution of NaCl
2. mixture of pentane and hexane
3. mixture of ethanol and water
all 3
most similar intermolecular forces = miscible
same homologous forces
ethanol and water are really good homogenous mixture – both have H bonding
butanol and above = not miscible (larger C chain = more significant london forces)
what is the maximum number of electrons tat can occupy the 4th shell in the atom (n=4)
formula: 2n^2
2(4)^2 = 32
how does a more negatively charged ion affect repulsion (and hence ionic radius)
more -ve = more repulsion = larger ionic radii
what is the geometry around a carbon atom in graphene?
1. hexagonal
2. pyramidal
3. tetrahedral
4. trigonal planar
trigonal planar
(technically in hexagonal form but. graphite is trigonal planar.)
is XeF2 or SF2 nonpolar?
XeF2 is nonpolar – has a linear geometry
SF2 has a bent geometry
how to tell which compound has smallest lattice energy?
has components furthest from the top right corner.
larger charge + smaller radii = higher lattice e
(so avoid that lawl)
which equation represents entahlpy of hydration of bromide ions?
1. Br2 (g) –> 2Br- (aq)
2. Br- (g) –> Br- (aq)
its 2 bitch
which of the following occurs during the Winkler test used to determine the concentration of dissolved oxygen in water
1. manganese(II) species is oxidised
2. iodine is reduced by oxygen to iodide ions
3. oxygen is oxidised
4. thiosulfate ions are reduced
1
first mn2sulfate is added, oxidation to mn(iv)
then add acidified potassium iodide KI – mv4 back to mn2 + iodine liberated
thiosulfate + starch indicator –> titrate the iodine
moles of iodine = can work out moles of o2
o2 content usually presented as ppm or mg/dm3
current flows thru 2 electrolytic cells, one w molten NaCl and another with molten MgCl2 – which has a larger mass of metal produced?
NaCl
even tho Mg is heavier than Na, to prod Cl2 gas 2Na is produced while 1Mg is prod
what are the E(o) and (triganle)G(o) values for a spontaneous reaction?
E not? is POSITIVE
G is NEGATIVE
esterification – naming? which comes first between the one with the C=O and the one connected to the other O
the one with the other O comes first THEN. the one with C=O
eg methyl propanoate
cis vs trans isomers
for something to be a cis/trans isomer it NEEDS to have 2 diff groups on BOTH sides of the C=C
- having 2 of the same group with a C does not make it cis
- only works if there are 2 of the SAME GRP (if all diff = ez isomer)
- if its a ring they gotta be on opposite sides but gotta look at the triangles if they’re bold or dotted
cis – same side of bond
trans – opposite sides of bond
E vs Z isomers
- look at the groups on each carbon – the one with an ATOM of LARGER ATOMIC NUMBER is higher priority
- E = on opposite sides
- Z = on same side
- look at first carbon attached first then move down the group until u find something to differentiate
what is the number and splitting pattern of signals in HNMR of propanone
1 signal
singlet
which statements about the isotopes 203Ti and 205Ti are correct?
1. same physical properties
2. same chemical properties
3. 205 deflected less than 203 in mass spectrometer
2 and 3
describe the intramolecular bonding in NH4+
electrostatic attractions btween pairs of electrons and positively charged nuclei
highest heat capacity = show lowest/highest incr in temperature when heat is supplied
higher the heat capacity. lower the temperature incr
which equation represents the standard entahlpy change of formation of water?
- h2(g) + 0.5o2(g) –> h2o (g)
- –> h2o(l)
2
formula for enthalpy of hydration
solution + lattice
classify this reaction:
NH4Br + KNH2 –> KBr + 2NH3
- acid-base
- condensation
- disproportionation
- reduction-oxidation
it is an ACID BASE
i guess the ‘salt’ formed is KBr????
disproportionation – one thing simultaneously oxidised and reduced
positve E knot value = oxidising/reducing agents?
oxidising
more positve E knot value = reactant is LESS/MORE thermodynamically stable?
LESS
what rotates plane polarised light
chiral molecules
2-bromobutane reacts with aq NaOH via bimolecular nucleophilic substitution; which are correct abt this mechanism?
1. there is an inversion of configuration between the resulting product and 2-bromobutane
2. its a single-step reaction
3. favours formation of carbonation intermediate
1 and 2
what conditions favour a unimolecular nucleophillic substitution reaction?
type of halogenoalkane: tertiary / primary
type of solvent: polar aprotic / polar protic
tertiary and polar protic
tertiary halogenoalkane
the C the halogen is attached to is connected to 3 other Cs
a well tested scientific idea which has been used to make predictions cannot explain a particular event. which statement described the scientific approach to this dilemma?
1. hypothesis should be revised
2. theory should be revised
3. hypothesis should be discarded
4. theory should be discarded
2
obviously dont throw it all away
hypothesis is used to make predictions – theory can be changed to include something for that event
whcih are pre-combustion methods of reducing sulfur dioxide emissions?
1. wash flue gases with crushed limestone and water
2. crush and wash the coal
3. crush and mix coal with a sulfur solvent then wash
2 and 3
which reaction is most likely to be spontaneous?
enthalpy change: exothermic / endo
entropy: incr / decr
enthalpy change is exothermic
(endo = req energy to activate ? so not spontaneous)
incr entropy
G (needs -ve) = enthalpy change - change in entropy
which of the following is not amphiprotic
1 H2O
2 HPO4 2-
3 H2PO4 -
4 H3O +
H3O + like bitch you ever seen H4O 2+ yeah thought not anyways amphiprotic means can donate and receive a proton
buffer belongs to the side of the ph range of the WEAK / STRONG component
weak
so if the acid is weak ur buffer region finna be
products at cathode and anode when molten NaCl is hydrolysed?
cathode: sodium
anode: chlorine
electrophillic substitution of a benzene ring is usually the addition of a ? group
NO2 (nitration)
