Join TSR now and get all your revision questions answeredSign up now

OCR Salters Chemistry F335 12th June 2013 Exam revision thread Watch

    Offline

    2
    ReputationRep:
    (Original post by Futuristicmedic)
    I put more carbonate produced and eq shifts right, then more carbonate reacts with ca2+ and so less is available to produce caco3 so shell is weaker


    Posted from TSR Mobile
    Damn. I wrote the complete opposite. I said the shell gets stronger.
    • PS Helper
    Offline

    0
    ReputationRep:
    prove Ka = 1.7E-4, when pH is 3.77.

    Then pH when HA = A-, 3.77.

    pH when half acid has reacted with NaOH, pH = 4.07
    • PS Helper
    Offline

    2
    ReputationRep:
    (Original post by Mattywooda)
    Fairly sure it was oxidation? Losing a hydrogen is that...
    Agghh. I wrote that first, then changed it :facepalm:

    Got the same pH values as you for the buffers.

    Posted from TSR Mobile
    Offline

    0
    ReputationRep:
    (Original post by Reina)
    Trans chains are straighter and more regular so they can line up and pack together more closely. This means intermolecular bonds are stronger and more numerous because there are more points of contact so more idid bonds form and the chains require more energy to separate.
    I put they way more points of contact, they was less distance between some parts of the chains unlike in cis were the chains where straighter but prevented from packing closely by the ester bond. This means the intemolecular forces ( instantenuos induced dipole interctions) are strong in trans oil so more energy need to separate out the chains inorder to boil the liquid.
    • PS Helper
    Offline

    0
    ReputationRep:
    (Original post by EdwinLo)
    Humans are mammals too so surely it is toxic to humans just to inhale?
    Yeah.

    "Damn. I wrote the complete opposite. I said the shell gets stronger."

    It's in storylines
    Offline

    0
    ReputationRep:
    what did everyone put for the transition metal & coloured complex 5 or 6 marker ?
    Spoiler:
    Show
    I put ligands split the d-orbitals of transition metals into two levels, a higher and a lower, and electrons can be excited from the lower level to the higher level. Since delta E = hv the colour transmitted depends on the frequency of energy absorbed and therefore the difference between energy levels. Complementary colour transmitted to that absorbed. QWC 1 mark?

    I'm worried because I put "emit" as well as transmit in my description though.
    Offline

    0
    ReputationRep:
    (Original post by millz186)
    does anyone remember the answers for the pH calculations?
    I got 3 point something for the one that was followed by the "which assumption makes the calculation less accurate" question (or something along those lines).
    Offline

    0
    ReputationRep:
    I put 2HCOOH + CaCO3 = CO2 + H2O + CA(OH)2 ...... is that wrong?
    Offline

    1
    ReputationRep:
    (Original post by Mattywooda)
    Fairly sure it was oxidation? Losing a hydrogen is that...
    It lost a proton so there was no change in electrons.
    Offline

    0
    ReputationRep:
    (Original post by EdwinLo)
    Humans are mammals too so surely it is toxic to humans just to inhale?
    inhaling? perhaps but i was thinking that humans would eat the insecticide at higher concentration that were more toxic
    Offline

    0
    ReputationRep:
    (Original post by C.JTop)
    I put they way more points of contact, they was less distance between some parts of the chains unlike in cis were the chains where straighter but prevented from packing closely by the ester bond. This means the intemolecular forces ( instantenuos induced dipole interctions) are strong in trans oil so more energy need to separate out the chains inorder to boil the liquid.
    Ditto. Do you think if I stated pd-pd as an interaction between the hydrocarbon chains that I'll lose a mark?
    Offline

    0
    ReputationRep:
    (Original post by AmirHabeeb)
    It lost a proton so there was no change in electrons.
    yeah the Nitrogen was N- , so i put reduction?
    Offline

    1
    ReputationRep:
    (Original post by C.JTop)
    yeah the Nitrogen was N- , so i put reduction?
    Oxidation/Reduction involve a change in number of electrons. There was no change. I think it's elimination.
    Offline

    0
    ReputationRep:
    (Original post by autodidactmedic)
    what did everyone put for the transition metal & coloured complex 5 or 6 marker ?
    Spoiler:
    Show
    I put ligands split the d-orbitals of transition metals into two levels, a higher and a lower, and electrons can be excited from the lower level to the higher level. Since delta E = hv the colour transmitted depends on the frequency of energy absorbed and therefore the difference between energy levels. Complementary colour transmitted to that absorbed. QWC 1 mark?

    I'm worried because I put "emit" as well as transmit in my description though.
    I didn't know whether to write about ligands since I think it said "transition metal compounds" rather than "complexes".

    My answer was "Electrons absorb light energy and move to higher energy levels. The frequency absorbed depends on the energy gap between two energy levels (deltaE = hv). The complimentary colour is reflected or transmitted."

    It didn't feel like enough, but the question was 5 marks - one being QWC
    Offline

    2
    ReputationRep:
    What do people think the grade boundaries will be??

    Posted from TSR Mobile
    Offline

    0
    ReputationRep:
    (Original post by autodidactmedic)
    Ditto. Do you think if I stated pd-pd as an interaction between the hydrocarbon chains that I'll lose a mark?
    yeah maybe, they both would have the same strength of pd-pd forces i think, so that wouldn't be a factor
    • PS Helper
    Offline

    0
    ReputationRep:
    (Original post by chemistryfailure)
    I put 2HCOOH + CaCO3 = CO2 + H2O + CA(OH)2 ...... is that wrong?
    I think it should be:

    2HCOOH + CaCO3 ==> CO2 + H20 + Ca(HCOO)2
    Offline

    0
    ReputationRep:
    (Original post by Reina)
    I didn't know whether to write about ligands since I think it said "transition metal compounds" rather than "complexes".

    My answer was "Electrons absorb light energy and move to higher energy levels. The frequency absorbed depends on the energy gap between two energy levels (deltaE = hv). The complimentary colour is reflected or transmitted."

    It didn't feel like enough, but the question was 5 marks - one being QWC
    I know, if they meant we should describe ligands then that is not your fault as they should have made it clearer. I bet in the right hand column of the mark scheme it will say "emit = CON." ​Damn you OCR
    Offline

    0
    ReputationRep:
    how did people answer the acid question where it said half of the acid had reacted with sufficient amounts of NaOH??
    Offline

    0
    ReputationRep:
    (Original post by AmirHabeeb)
    Oxidation/Reduction involve a change in number of electrons. There was no change. I think it's elimination.
    oh i see what you mean now
 
 
 
Poll
Should MenACWY vaccination be compulsory at uni?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.