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

    3
    ReputationRep:
    Right so I was doing a bit of revision on group 2.

    why does magnesium deviate from the trend in the melting points. Also what are used if the hydroxides. Can someone also explain the test for knowing a sulphate and why does barium chloride have to be acidified?
    Offline

    3
    ReputationRep:
    (Original post by Super199)
    Right so I was doing a bit of revision on group 2.

    why does magnesium deviate from the trend in the melting points. Also what are used if the hydroxides. Can someone also explain the test for knowing a sulphate and why does barium chloride have to be acidified?
    The melting point is to do with the structure of magnesium. Check chemguide
    Knowing a sulphate you have to add acidified (with HCl) BaCl2(aq) and if sulphate is present there will be white precipitate. This is because barium sulphate is insoluble.
    Barium chloride must be acidified with HCl to eliminate the possibilities of other ions mainly carbonate which can also form precipitate

    Posted from TSR Mobile
    Offline

    3
    ReputationRep:
    What is magnesium hydroxide, calcium hydroxide and barium sulphate used for? Are those the only I end I need uses for.

    I know barium sulphate is used in x-rays not exactly sure how it works. If you don't mind explains each of the uses it would be appreciated.

    Thanks for the help
    Offline

    2
    ReputationRep:
    (Original post by Super199)
    What is magnesium hydroxide, calcium hydroxide and barium sulphate used for? Are those the only I end I need uses for.

    I know barium sulphate is used in x-rays not exactly sure how it works. If you don't mind explains each of the uses it would be appreciated.

    Thanks for the help
    you can use calcium hydroxide to test for carbon dioxide, its also known as limewater, if you bubble CO2 through it then it'll turn milky.

    Barium sulfates used in medicine as a barium meal, its insoluble so when people drink it you can use x rays to see what damage there is as it'll come up on the screen as..well a white precipitate.

    magnesium hydroxide is used as antacids for stomach pH.
    Offline

    2
    ReputationRep:
    (Original post by Kadak)
    Posted from TSR Mobile

    Hydrogenation is when you add hydrogen gas to a unsaturated alkenes, which then makes a saturated alkane.
    The pic below explains it all.
    That's great, thanks!
    Offline

    2
    ReputationRep:
    (Original post by Super199)
    What is magnesium hydroxide, calcium hydroxide and barium sulphate used for? Are those the only I end I need uses for.

    I know barium sulphate is used in x-rays not exactly sure how it works. If you don't mind explains each of the uses it would be appreciated.

    Thanks for the help
    Calcium Hydroxide can also be used by farmers to reduce soil acidity so a range of plants/crops can be grown. And a bonus is that the Calcium ions help the plants grow
    Offline

    2
    ReputationRep:
    (Original post by Super199)
    Right so I was doing a bit of revision on group 2.

    why does magnesium deviate from the trend in the melting points. Also what are used if the hydroxides. Can someone also explain the test for knowing a sulphate and why does barium chloride have to be acidified?
    Magnesium deviates from the trend because it has a different crystal structure from the other metals. Magnesium has a hexagonal close-packed structure, whereas calcium and strontium have face-centred cubic structures and barium has a body-centred cubic structure.

    The test for sulphate ions: Add dilute hydrochloric (or nitric) acid and a solution of barium ions ( from barium chloride or barium nitrate) to the solution being tested. The appearance of a white precipitate indicates the presence of sulfate ions. (The barium ions will react with the sulfate ions in the solution to form barium sulfate which is a white precipitate)

    Why does barium chloride have to be acidifed?
    If you didnt add acid, carbonate ions would interfere with this test. If there are carbonate ions present in the solution being tested, they would also react with the barium ions to form a white precipitate. So you wouldn't know if the white precipitate was due to the presence of sulfate ions, or carbonate ions.

    By acidifying the barium chloride, the carbonate ions will react with the acid to generate carbon dioxide gas, and thereby removing them from the solution and preventing them from reacting with barium ions to form a white precipitate.
    Offline

    2
    ReputationRep:
    Can somebody explain to me how hydrogenation is linked to margarine? I understand the mechanism and the chemistry bit, its just these wordy questions like what is it used for where I lose marks!
    Offline

    2
    ReputationRep:
    (Original post by jontypickles)
    Can somebody explain to me how hydrogenation is linked to margarine? I understand the mechanism and the chemistry bit, its just these wordy questions like what is it used for where I lose marks!


    Posted from TSR Mobile

    Using hydrogenation, you can harden polyunsaturated vegetable oils, since the hydrogenation affects how the oil hardens.
    The two pics below should help.
    Attached Images
      
    Offline

    3
    ReputationRep:
    Does anyone know where I can find some sort of map of the organic reactions? Something where like alkenes -hydrogenation-> alkanes, primary alcohols -distil oxidation-> aldehydes etc?
    Offline

    2
    ReputationRep:
    Ocr January 2010 question 4b: why does it say 'using your knowledge of group 7 elements, complete the electron configuration of bromine'? How is the electron configuration of group 7 elements any different to others?


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    (Original post by anoymous1111)
    Ocr January 2010 question 4b: why does it say 'using your knowledge of group 7 elements, complete the electron configuration of bromine'? How is the electron configuration of group 7 elements any different to others?


    Posted from TSR Mobile


    Posted from TSR Mobile

    Pic pls?
    Offline

    2
    ReputationRep:
    Name:  ImageUploadedByStudent Room1428242338.066497.jpg
Views: 174
Size:  131.6 KB Thanks


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    (Original post by anoymous1111)
    Name:  ImageUploadedByStudent Room1428242338.066497.jpg
Views: 174
Size:  131.6 KB Thanks


    Posted from TSR Mobile


    Posted from TSR Mobile

    Yeah,they do that all the time.It's only 1 mark,it's just testing your abilitu to write out the orbitals of elements.

    Also for disadvantage of chlorine,I would think saying they form chlorinated hydrocarbons which are carcinogenic, would have been a better answer.
    Offline

    2
    ReputationRep:
    (Original post by Kadak)
    Posted from TSR Mobile

    Yeah,they do that all the time.It's only 1 mark,it's just testing your abilitu to write out the orbitals of elements.

    Also for disadvantage of chlorine,I would think saying they form chlorinated hydrocarbons which are carcinogenic, would have been a better answer.
    Great thank you


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    Can someone explain how to suggest the formula of sodium chlorate(VII). Can you explain the stages to figuring it out? Thank


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    (Original post by anoymous1111)
    Can someone explain how to suggest the formula of sodium chlorate(VII). Can you explain the stages to figuring it out? Thank


    Posted from TSR Mobile


    Posted from TSR Mobile

    Is the answer NACLO with a +4 charge overall?
    Offline

    2
    ReputationRep:
    (Original post by Kadak)
    Posted from TSR Mobile

    Is the answer NACLO with a +4 charge overall?
    It's NaClO4


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    (Original post by Kadak)
    Posted from TSR Mobile

    Is the answer NACLO with a +4 charge overall?
    I think it's because in this case Cl is 1+ and O4 is 4x-2 = -8. -8+1= -7 (VII)


    Posted from TSR Mobile
    Offline

    2
    ReputationRep:
    Alkenes are hydrated into alkanes, not hydrogenated some sort of flowchart would be useful, is this a resource anyone has?
 
 
 
Poll
Which web browser do you use?

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.