# Chemistry AS level question

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#1
Can someone pls help me ?
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1 month ago
#2
1- It is true because one mole of any substance contains 6.02 x 10^23 particles, and one mole of H2SO4 contains 2 x6.02x10^23 of hydrogen, 1x6.02x10^23 sulfur, and 4x6.02x10^23 oxygen
2-Not true because it is not a weak acid so the concentration of hydrogen ions would be higher than the concentration of HSO4
3- Not true because sulfur contains 16 electrons and 4 oxygens contain 64 electrons
Double check tho cuz iam not a 100% sure
Last edited by Zoolato24811; 1 month ago
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#3
(Original post by Zoolato24811)
1- It is true because one mole of any substance contains 6.02 x 10^23 particles, and one mole of H2SO4 contains 2 x6.02x10^23 of hydrogen, 1x6.02x10^23 sulfur, and 4x6.02x10^23 oxygen
2-Not true because it is not a weak acid so the concentration of hydrogen ions would be higher than the concentration of HSO4
3- Not true because sulfur contains 16 electrons and 4 oxygens contain 64 electrons
Double check tho cuz iam not a 100% sure
Can you please elaborate on the last one
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1 month ago
#4
(Original post by mh2410)
Can you please elaborate on the last one
Sulfur proton number is 16 so it has 16 electrons
Oxygen proton number is 8 so it has 8 electrons

Total number of moles of electrons = 16 from sulfur + 8 x 4 from oxygen + 2 responsible for negative charge
which is greater than 2 hence not 3

the answer is D, 1 only
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1 month ago
#5
(Original post by mh2410)
Can someone pls help me ?
I would say that 1 and 3 are correct.
Zoolato24811 reasoning is right, but i'm quite sure that statement 3 is correct as well as statement 1.

Statement 3 is correct because, 1 mole of SO4(2-) ions would have two moles of electrons. If 1 SO4(2-) ion has 2 electrons, make the ratio of 1:2.
Multiplying by avogadro's constant and you'd get that for 1 mole of SO4(2-) ions there would be 2 moles of electrons.

Like if you had 1 mole of NO3(-) ions, there would be one mole of electrons - because the ion:electron ratio is 1:1.
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1 month ago
#6
(Original post by NimitMistry13)
I would say that 1 and 3 are correct.
Zoolato24811 reasoning is right, but i'm quite sure that statement 3 is correct as well as statement 1.

Statement 3 is correct because, 1 mole of SO4(2-) ions would have two moles of electrons. If 1 SO4(2-) ion has 2 electrons, make the ratio of 1:2.
Multiplying by avogadro's constant and you'd get that for 1 mole of SO4(2-) ions there would be 2 moles of electrons.

Like if you had 1 mole of NO3(-) ions, there would be one mole of electrons - because the ion:electron ratio is 1:1.
No statement 3 is wrong.

You say SO4(2-) ion has 2 electrons.
S has 16 protons and O has 8 protons. The ion thus contains 48 protons. By your logic the ion should have a charge of +46. Which is clearly wrong
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#7
(Original post by golgiapparatus31)
No statement 3 is wrong.

You say SO4(2-) ion has 2 electrons.
S has 16 protons and O has 8 protons. The ion thus contains 48 protons. By your logic the ion should have a charge of +46. Which is clearly wrong
Now I’m confused even more 🤣🤣so how many moles of electrons it contains
Last edited by mh2410; 1 month ago
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1 month ago
#8
(Original post by golgiapparatus31)
Sulfur proton number is 16 so it has 16 electrons
Oxygen proton number is 8 so it has 8 electrons

Total number of moles of electrons = 16 from sulfur + 8 x 4 from oxygen + 2 responsible for negative charge
which is greater than 2 hence not 3

the answer is D, 1 only
The extra 2 electrons responsible for the negative charge come from the oxygen atoms so you dont count them again.
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1 month ago
#9
(Original post by mh2410)
Now I’m confused even more 🤣🤣so how many moles of electrons it contains
50
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1 month ago
#10
(Original post by Zoolato24811)
The extra 2 electrons responsible for the negative charge come from the oxygen atoms so you dont count them again.
You do. SO4(2-) contains 50 electrons.
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1 month ago
#11
(Original post by golgiapparatus31)
You do. SO4(2-) contains 50 electrons.
Nope it contains 80 electrons
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1 month ago
#12
(Original post by Zoolato24811)
Nope it contains 80 electrons
No.
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#13
(Original post by golgiapparatus31)
No.
Guys I feel we have to make ionic equation out of it , when I made it for the individual ions , and added the results by making H2SO4 1 mole , there were no moles of electrons anyway , cuz the charge balances by the H+ ions
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1 month ago
#14
(Original post by golgiapparatus31)
No.
4*16=64
1*16=16
They are joined by covalent bonds and no electrons are introduced from outside
16+64=80
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1 month ago
#15
(Original post by mh2410)
Guys I feel we have to make ionic equation out of it , when I made it for the individual ions , and added the results by making H2SO4 1 mole , there were no moles of electrons anyway , cuz the charge balances by the H+ ions
Even if the charge is balanced that doesnt mean that the electrons disappear
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1 month ago
#16
(Original post by Zoolato24811)
1- It is true because one mole of any substance contains 6.02 x 10^23 particles, and one mole of H2SO4 contains 2 x6.02x10^23 of hydrogen, 1x6.02x10^23 sulfur, and 4x6.02x10^23 oxygen
2-Not true because it is not a weak acid so the concentration of hydrogen ions would be higher than the concentration of HSO4
3- Not true because sulfur contains 16 electrons and 4 oxygens contain 64 electrons
Double check tho cuz iam not a 100% sure
That's wrong. You say "sulfur contains 16 electrons and 4 oxygens contain 64 electrons". You imply that oxygen and sulfur atoms have the same number of electrons which is untrue.

Oxygen atom has 8 electrons, not 16.

(Original post by mh2410)
Guys I feel we have to make ionic equation out of it , when I made it for the individual ions , and added the results by making H2SO4 1 mole , there were no moles of electrons anyway , cuz the charge balances by the H+ ions
An oxygen atom contains 8 electrons.
A mole of oxygen atoms contains 8 moles of electrons.

Review post 6
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1 month ago
#17
(Original post by Zoolato24811)
4*16=64
1*16=16
They are joined by covalent bonds and no electrons are introduced from outside
16+64=80
Electrons ARE introduced from the outside. 2 electrons that are responsible for the negative charged are acquired from the outside
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#18
They r talking about 1 mole of contains how many electrons SO4-2 contains , when H2SO4 dissociates into SO4-2, it has no moles of electrons produced with it. If we go according to what u guys are saying , why would examiner say 2 moles of electrons and make the value far from the real value
Last edited by mh2410; 1 month ago
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1 month ago
#19
(Original post by mh2410)
They r talking about 1 mole of contains how many electrons SO4-2 contains , when H2SO4 dissociates into SO4-2, it has no moles of electrons produced with it. If we go according to what u guys are saying , why would examiner say 2 moles of electrons and make the value far from the real value
"They r talking about 1 mole of contains how many electrons SO4-2 contains"
I assume you mean
"They r talking about 1 mole of SO42- contains how many electrons"

(a) How many electrons does an oxygen atom have?
(b) How many moles of electrons does a mole of oxygen atoms contain?

The dissociation of H2SO4 occurs in 2 steps:
H2SO4 -> H+ + HSO4-
HSO4- -> H+ + SO42-
The first dissociation is complete as H2SO4 is a strong acid.
The second dissociation is weak because HSO4- is a weak acid. But the concentration of H+ will be greater than the concentration of HSO4- because some HSO4- will dissociate. So 2 is wrong.
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#20
(Original post by golgiapparatus31)
"They r talking about 1 mole of contains how many electrons SO4-2 contains"
I assume you mean
"They r talking about 1 mole of SO42- contains how many electrons"

(a) How many electrons does an oxygen atom have?
(b) How many moles of electrons does a mole of oxygen atoms contain?

The dissociation of H2SO4 occurs in 2 steps:
H2SO4 -> H+ + HSO4-
HSO4- -> H+ + SO42-
The first dissociation is complete as H2SO4 is a strong acid.
The second dissociation is weak because HSO4- is a weak acid. But the concentration of H+ will be greater than the concentration of HSO4- because some HSO4- will dissociate. So 2 is wrong.
Why are you dissociating HSO4- if we need it to be dissociated from H2SO4
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