# IAL Edexcel A2 Chemistry Unit 6 (Old syllabus)Watch

1 week ago
#41
Yes hahaha
(Original post by ree.x09)
Are you from bd?
0

1 week ago
#42
Guys help

K so this question is from January 2018, Unit 4.
For Ethanoic acid, Pka=4.76. The pH of a solution of ethanoic acid with a concentration of 1×10^-10 mol dm^-3 is approximately :
A. 5.2
B. 7.0
C. 7.4
D. 15

The answer is B but i keep getting C no matter how I do it
0
1 week ago
#43
I think it's because ethanoic acid is a weak acid so partial dissociation occurs and it's neutral
(Original post by Erica.kh)
Guys help

K so this question is from January 2018, Unit 4.
For Ethanoic acid, Pka=4.76. The pH of a solution of ethanoic acid with a concentration of 1×10^-10 mol dm^-3 is approximately :
A. 5.2
B. 7.0
C. 7.4
D. 15

The answer is B but i keep getting C no matter how I do it
1
#44
(Original post by Erica.kh)
Guys help

K so this question is from January 2018, Unit 4.
For Ethanoic acid, Pka=4.76. The pH of a solution of ethanoic acid with a concentration of 1×10^-10 mol dm^-3 is approximately :
A. 5.2
B. 7.0
C. 7.4
D. 15

The answer is B but i keep getting C no matter how I do it
Gosh I spent like an hour on this question and this is what I came up with.
When u calculate using the assumption that no [H+] from water is ionized then u can use the standard idea and equation we use which is Ka=X^2/{CH4COOH].
When u apply this equation to the question u get 7.4, however if u dont assume no H+ came from water then the answer would be slightly more acidic due to the slight increase in H+ in the solution, from water.
In this case the next lowest ph is 7 which is more accurate as then u have also taken into consideration the [H+] from dissociation of water which also occurs, that in normal questions we assume hasn't occurred.

This is what I think they are implying on as thats what the mark scheme says too.
2
1 week ago
#45
(Original post by Erica.kh)
Guys help

K so this question is from January 2018, Unit 4.
For Ethanoic acid, Pka=4.76. The pH of a solution of ethanoic acid with a concentration of 1×10^-10 mol dm^-3 is approximately :
A. 5.2
B. 7.0
C. 7.4
D. 15

The answer is B but i keep getting C no matter how I do it
Simply you can't get pH greater than 7 if you have acid
0
1 week ago
#46
(Original post by ree.x09)
I needed help with a problem. But it’s solved now! ) Thanks anyway!
0
1 week ago
#47
why is nichrome wire dipped in HCl?
0
1 week ago
#48
(Original post by Starzzz)
why is nichrome wire dipped in HCl?
Flame test 🔥

Nichrome wire is dipped in concentrated HCl and then heated strongly to clean the wire. Then dipped in the acid again to moisten it then dipped into the sample/salt to pick up some of it, then the wire is held in the clear part of a HOT/ROARING flame and observe the color.
1
1 week ago
#49
Anyone chem unit 6 oct 2018 examiner report please??
0
1 week ago
#50
(Original post by yeswhynot76)
Anyone chem unit 6 oct 2018 examiner report please??
0
1 week ago
#51
(Original post by Keka Ferdousi)
I think it's because ethanoic acid is a weak acid so partial dissociation occurs and it's neutral
(Original post by Nabs78)
Gosh I spent like an hour on this question and this is what I came up with.
When u calculate using the assumption that no [H+] from water is ionized then u can use the standard idea and equation we use which is Ka=X^2/{CH4COOH].
When u apply this equation to the question u get 7.4, however if u dont assume no H+ came from water then the answer would be slightly more acidic due to the slight increase in H+ in the solution, from water.
In this case the next lowest ph is 7 which is more accurate as then u have also taken into consideration the [H+] from dissociation of water which also occurs, that in normal questions we assume hasn't occurred.

This is what I think they are implying on as thats what the mark scheme says too.
(Original post by CuriosityYay)
Simply you can't get pH greater than 7 if you have acid
Thanks guys !! That's probably what they meant cuz the mark scheme says something about taking H+ ions from water into consideration
0
1 week ago
#52
can someone help me solve this unit 5 chem question in the jan 2014 wcho paper
its question 21 part 4
0
1 week ago
#53
(Original post by lavacake)
can someone help me solve this unit 5 chem question in the jan 2014 wcho paper
its question 21 part 4
part 4?
https://qualifications.pearson.com/c...e_20140121.pdf
0
1 week ago
#54
oops,21 b part iv)
0
1 week ago
#55
(Original post by lavacake)
oops,21 b part iv)
Page 10
https://qualifications.pearson.com/c...c_20140306.pdf
0
1 week ago
#56
yeah ive seen it but I don't get why its not done the usual way starting form the mno4- moles?

0
1 week ago
#57
Hey guys I had a question from physics unit 6.Why did we multiply the length with 4?
0
1 week ago
#58
(Original post by Keka Ferdousi)
Hey guys I had a question from physics unit 6.Why did we multiply the length with 4?
This is a chemistry thread bucko
0
1 week ago
#59
Lol sorry guys I posted this in the wrong thread
0
1 week ago
#60
(Original post by KSaRa)
Does anyone have any suggestions for which areas the paper might focus on?
#learn color of transition metals and the ligand
#learn methods of purification and separation
#Redox equations
2
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