A-level Chemistry Revision Squad!
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Original post by haj101
Can't open the attachment for some reason! 
Which paper was it from?
Which paper was it from?
Sorry I'm not sure what I did with that attachment haha
It was the final question on the unit 5 June 2013 paper
Original post by Louiseelg0rt
Sorry I'm not sure what I did with that attachment haha
It was the final question on the unit 5 June 2013 paper
It was the final question on the unit 5 June 2013 paper
Okay so you first have to calculate the moles of Cobalt in cobalt chloride:
50/1000 X 0.203= 0.01015 moles
Then we are given the information that AgCl is produced from reacting Z with silver nitrate so we can find out the moles of AgCl....
4.22/143.4 = 0.0294
The ratio is 0.01015:0.0294
we can divide each value by 0.01015 to get us:
2.9 : 1
Original post by haj101
Okay so you first have to calculate the moles of Cobalt in cobalt chloride:
50/1000 X 0.203= 0.01015 moles
Then we are given the information that AgCl is produced from reacting Z with silver nitrate so we can find out the moles of AgCl....
4.22/143.4 = 0.0294
The ratio is 0.01015:0.0294
we can divide each value by 0.01015 to get us:
2.9 : 1
50/1000 X 0.203= 0.01015 moles
Then we are given the information that AgCl is produced from reacting Z with silver nitrate so we can find out the moles of AgCl....
4.22/143.4 = 0.0294
The ratio is 0.01015:0.0294
we can divide each value by 0.01015 to get us:
2.9 : 1
Thanks! I got that bit, do you know how to go about the bit after that?
Original post by Louiseelg0rt
Thanks! I got that bit, do you know how to go about the bit after that?
I'm not too sure about the last bit im afraid
sorry about that!http://www.thestudentroom.co.uk/attachment.php?attachmentid=544235
Hey im not sure on some Unit 4 Qs. 6b ( why is there permamnent dipole dipole interactions...is it due to the polar alcohol bond) and 6c ( the wrong answer c seems feasible to me but why is that fragments without H are unlikely)Thanks in advance @TeachChemistry
Hey im not sure on some Unit 4 Qs. 6b ( why is there permamnent dipole dipole interactions...is it due to the polar alcohol bond) and 6c ( the wrong answer c seems feasible to me but why is that fragments without H are unlikely)Thanks in advance
@TeachChemistry(edited 7 years ago)
Original post by ayvaak
http://www.thestudentroom.co.uk/attachment.php?attachmentid=544235
Hey im not sure on some Unit 4 Qs. 6b ( why is there permamnent dipole dipole interactions...is it due to the polar alcohol bond) and 6c ( the wrong answer c seems feasible to me but why is that fragments without H are unlikely)Thanks in advance @TeachChemistry
Hey im not sure on some Unit 4 Qs. 6b ( why is there permamnent dipole dipole interactions...is it due to the polar alcohol bond) and 6c ( the wrong answer c seems feasible to me but why is that fragments without H are unlikely)Thanks in advance
@TeachChemistry6b: C-O bond polar
6c: If you draw out the structural formula you will not be able to break bonds anywhere to give fragment C.
(edited 7 years ago)
Chemistry unit 5
January 2010
Question 3h
Is it okay to say:
Electrolysis of water to obtain hydrogen uses fossil fuels so not carbon neutral
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January 2010
Question 3h
Is it okay to say:
Electrolysis of water to obtain hydrogen uses fossil fuels so not carbon neutral
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I don't understand why the answer is B, I thought because since 1 mol of chromium(III) sulphate has 392g, hence the standard would also contain 392g since it also should have a 1moldm3 concentration ?
Original post by PlayerBB
I don't understand why the answer is B, I thought because since 1 mol of chromium(III) sulphate has 392g, hence the standard would also contain 392g since it also should have a 1moldm3 concentration ?
You want 1M of the ion.
Original post by Bloom77
Chemistry unit 5
January 2010
Question 3h
Is it okay to say:
Electrolysis of water to obtain hydrogen uses fossil fuels so not carbon neutral
Posted from TSR Mobile
January 2010
Question 3h
Is it okay to say:
Electrolysis of water to obtain hydrogen uses fossil fuels so not carbon neutral
Posted from TSR Mobile
Yeah
Original post by alow
You want 1M of the ion.
So the 392g represent 2M of Cr3+ and for a standard solution, we need a 1M of Cr3+ so 392/2 ?
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Original post by PlayerBB
So the 392g represent 2M of Cr3+ and for a standard solution, we need a 1M of Cr3+ so 392/2 ?
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Posted from TSR Mobile
I think so, yeah.
Bit messy but how many marks would this be
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Original post by Supermanxxxxxx
One
1.
You gained the first mark
2.
You shouldn't leave the receiver like this with a large gap between the delivery tube and the receiver and you should include a small opening within the tube itself and it should be after the condenser to prevent the build up of pressure
3.
You lost the third mark because you didn't include the thermometer in which the thermometer bulb should oppose the opening of the condenser and also you didn't includea source of heating as an electric heater
(edited 7 years ago)
Original post by PlayerBB
Can someone help me with (c), I can't figure it out ?
Is the answer d
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Original post by Supermanxxxxxx
Yeah! How ? Is it because when the propanoyl chloride reacts with water, it produces propanoic acid + HCl gas which cause the solution to become more acidic than propanoic acid alone ?
(edited 7 years ago)
Original post by PlayerBB
Yeah! How ?
Acyclovir chlorides along with water will produce a carboxylic acid and hcl
And hcl is a strong acid which can dissociate fully
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Original post by Supermanxxxxxx
Acyl chlorides along with water will produce a carboxylic acid and hcl
And hcl is a strong acid which can dissociate fully
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And hcl is a strong acid which can dissociate fully
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Posted from TSR Mobile
Original post by Supermanxxxxxx
Acyclovir chlorides along with water will produce a carboxylic acid and hcl
And hcl is a strong acid which can dissociate fully
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And hcl is a strong acid which can dissociate fully
Posted from TSR Mobile
Ah thanks but isn't it HCl gas that is produced and it should evaporate ?
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