AS Chemistry- helping each other out!
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(edited 9 years ago)
OCR A! wow Im so late
Help!
When chlorine is added to a solution containing bromide or iodide ions, a colour change occurs. What solvent would you add to the mixture to confirm the identity of the halogen produced?
Is it not AgNO3...? and the result a cream ppt? (next question asked the result for if bromine was produced)
When chlorine is added to a solution containing bromide or iodide ions, a colour change occurs. What solvent would you add to the mixture to confirm the identity of the halogen produced?
Is it not AgNO3...? and the result a cream ppt? (next question asked the result for if bromine was produced)
Original post by Nautic4l
Help!
When chlorine is added to a solution containing bromide or iodide ions, a colour change occurs. What solvent would you add to the mixture to confirm the identity of the halogen produced?
Is it not AgNO3...? and the result a cream ppt? (next question asked the result for if bromine was produced)
When chlorine is added to a solution containing bromide or iodide ions, a colour change occurs. What solvent would you add to the mixture to confirm the identity of the halogen produced?
Is it not AgNO3...? and the result a cream ppt? (next question asked the result for if bromine was produced)
you add acidified silver nitrate (acidified to get rid of any unwanted ions i.e CO32-) the result would be cream ppt of silver bromide.
Original post by ThatMadClown
you add acidified silver nitrate (acidified to get rid of any unwanted ions i.e CO32-) the result would be cream ppt of silver bromide.
The mark scheme says 'A hydrocarbon (solvent) / volasil /named hydrocarbon solvent /tetrachloromethane' and 'Red / brown /orange / amber / yellowOr any combinationNo TE on incorrect / no reagent' for the result Q
Original post by Nautic4l
Help!
When chlorine is added to a solution containing bromide or iodide ions, a colour change occurs. What solvent would you add to the mixture to confirm the identity of the halogen produced?
Is it not AgNO3...? and the result a cream ppt? (next question asked the result for if bromine was produced)
When chlorine is added to a solution containing bromide or iodide ions, a colour change occurs. What solvent would you add to the mixture to confirm the identity of the halogen produced?
Is it not AgNO3...? and the result a cream ppt? (next question asked the result for if bromine was produced)
Yeah AgNO3 is the common standard; will produce Ag+ ions in the mixture and it's the precipitate that forms with the halide ions you react it with that will give you the different colours.
AgBr is cream coloured if I remember correctly
AgI is yellow.
Original post by James A
Yeah AgNO3 is the common standard; will produce Ag+ ions in the mixture and it's the precipitate that forms with the halide ions you react it with that will give you the different colours.
AgBr is cream coloured if I remember correctly
AgI is yellow.
AgBr is cream coloured if I remember correctly
AgI is yellow.
Read my other reply too please! I'm confused haha
Original post by Nautic4l
Read my other reply too please! I'm confused haha
You add silver nitrate as a standard method to getting a ppt
Let's say you've got a solution of bromoethane, you add sodium hydroxide to it, these react releasing the Br- ion, I'm going to assume that you know the mechanism behind this? But now youve got bromide ions in the solution, after the addition of silver nitrate you should be getting a ppt of the silver bromide.
Original post by ThatMadClown
You add silver nitrate as a standard method to getting a ppt
Let's say you've got a solution of bromoethane, you add sodium hydroxide to it, these react releasing the Br- ion, I'm going to assume that you know the mechanism behind this? But now youve got bromide ions in the solution, after the addition of silver nitrate you should be getting a ppt of the silver bromide.
Let's say you've got a solution of bromoethane, you add sodium hydroxide to it, these react releasing the Br- ion, I'm going to assume that you know the mechanism behind this? But now youve got bromide ions in the solution, after the addition of silver nitrate you should be getting a ppt of the silver bromide.
That's not what it says on the mark scheme. I quoted you previously
Original post by Nautic4l
That's not what it says on the mark scheme. I quoted you previously
Can you post a pic of the question ?
Original post by ThatMadClown
Can you post a pic of the question ?
I'll link you both the paper and the mark scheme in just a second
Original post by ThatMadClown
Can you post a pic of the question ?
http://qualifications.pearson.com/content/dam/pdf/A%20Level/Chemistry/2013/Exam%20materials/6CH02_01_que_20100121.pdf
17ai/ii
and mark scheme here: http://qualifications.pearson.com/content/dam/pdf/A%20Level/Chemistry/2013/Exam%20materials/6CH02_01_msc_10022010_US022678.pdf
Have never come across this test before in 2 years of A-Level Chemistry.
Original post by Nautic4l
http://qualifications.pearson.com/content/dam/pdf/A%20Level/Chemistry/2013/Exam%20materials/6CH02_01_que_20100121.pdf
17ai/ii
and mark scheme here: http://qualifications.pearson.com/content/dam/pdf/A%20Level/Chemistry/2013/Exam%20materials/6CH02_01_msc_10022010_US022678.pdf
Have never come across this test before in 2 years of A-Level Chemistry.
17ai/ii
and mark scheme here: http://qualifications.pearson.com/content/dam/pdf/A%20Level/Chemistry/2013/Exam%20materials/6CH02_01_msc_10022010_US022678.pdf
Have never come across this test before in 2 years of A-Level Chemistry.
the best thing to do would be writing that answer in your notes. Im on AQA and we do the silver nitrate test.
Original post by ThatMadClown
the best thing to do would be writing that answer in your notes. Im on AQA and we do the silver nitrate test.
Cheers! It's an old paper so maybe it's not on the papers anymore but I might as well I think!
http://qualifications.pearson.com/content/dam/pdf/A%20Level/Chemistry/2013/Exam%20materials/6CH01_01_que_20110113.pdf
May someone explain to me why in Q6a) why Answer A can be completely ruled out?
and I don't get Q11)
thankyou
May someone explain to me why in Q6a) why Answer A can be completely ruled out?
and I don't get Q11)
thankyou
Out of curiosity to those of you doing the Empa on AQA, when are you doing this?
I am going over Hess' law cycles and I can't seem to remember why standard enthalpy change of formation always needs 1 mole of product on the right hand side and why combustion always has 1 mole of elements and compounds on the left side of the equation.
All I know is that it does! But whyyy?
Thanks
All I know is that it does! But whyyy?
Thanks
Original post by Super199
Out of curiosity to those of you doing the Empa on AQA, when are you doing this?
The week after easter
Posted from TSR Mobile
Original post by TheonlyMrsHolmes
I am going over Hess' law cycles and I can't seem to remember why standard enthalpy change of formation always needs 1 mole of product on the right hand side and why combustion always has 1 mole of elements and compounds on the left side of the equation.
All I know is that it does! But whyyy?
Thanks
All I know is that it does! But whyyy?
Thanks
Because that's the definition:
" Energy change of formation is the energy change when 1 mole of a compound is formed from its constituent elements in their standard states under standard conditions(298K 1atm)
Energy change of combustion is the energy when 1 mole of a substance is completely burned in an excess of oxygen under standard conditions " "
May you look at my post and help me please? I forgot about those things
Posted from TSR Mobile
Original post by frozo123
Because that's the definition:
" Energy change of formation is the energy change when 1 mole of a compound is formed from its constituent elements in their standard states under standard conditions(298K 1atm)
Energy change of combustion is the energy when 1 mole of a substance is completely burned in an excess of oxygen under standard conditions " "
May you look at my post and help me please? I forgot about those things
Posted from TSR Mobile
" Energy change of formation is the energy change when 1 mole of a compound is formed from its constituent elements in their standard states under standard conditions(298K 1atm)
Energy change of combustion is the energy when 1 mole of a substance is completely burned in an excess of oxygen under standard conditions " "
May you look at my post and help me please? I forgot about those things
Posted from TSR Mobile
Oh right thank you, thats be not bothering to look at my definitions lol and yeah sure one sec!
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