Any Chem AS question to be posted here :):)

[Haaks18]

all the questions right here will be mainly about Chem AS.. Here u can discuss and the questions u r confused about and OFCOURSE nothing is possible in SF

[Haaks18]

What does Shielding in the Atomic Structure chapter means??
And in Atomic Structure do we have to knw about Nuclear fission and fusion?!
Thanks aloot

[Amelia]

all the questions right here will be mainly about Chem AS.. Here u can discuss and the questions u r confused about and OFCOURSE nothing is possible in SF

You mean impossible, buddy. 

Sheilding Effect of Electrons in an atom.
All electrons are negetively charged and repel each other. Electrons in filled inner shells repel electrons in the outer shells and reduce the effect of positive nuclear charge. This is called Shielding effect. The greater the shielding effect upon an electron, the lower is the Ionization energy.

(These come under the heading of Nuclear Chemistry)
Nuclear Fission is when a nucleus splits into half and produces a great amount of energy. The energy generated by splitting the atom was called atomic energy.

Nuclear Fusion is when  two small nuclei such as those in Hydrogen combine to form a large nucleus. The energy is released in tremendous amount.

[Amelia]

You can post your doubts, here

https://studentforums.biz/sciences-149/chemistry-doubts-10366/
or here
https://studentforums.biz/sciences-149/edexcel-chemistry-doubts
(depending on what you take)

P.S - Good luck!

[AS-Girl]

hey again
i have a question that came to my mind yesterday..
we did solubiltiy product for compounds which have the same mole ratio like   AgCl---->Ag +   and Cl-

but what if the compound has a different miole ration like Mg(OH)2-------->Mg2+ and 2OH-

how can we get the solubility of both ions??

i know we get Ksp= [Mg2+] [Oh-]2

then what??

[Amelia]

For eg:- The Solubility Product of Mg(OH)₂ is 1.00x10^-12                        

                    Mg(OH)₂----->Mg²⁺+2OH^-


Ratio =                          1                  :          1              :       2

(2+1 = 3)
 Ksp = [Mg²⁺]³
find the cuberoot of 1.00x10^-12 = 1x10^-4 (this answer will be for Mg²⁺ since its ratio is 1)
For OH^- = 2x1x10^-4 = 2x10^-4
Since it is 2OH^-, we do 2x10^-4 = 4x10^-8

[Amelia]

I'll give another example with the same numbers.

The solubility product of Siver Chromate (Ag₂CrO₄)at 25degree celcius is 1.00x10^-12.
Calculate the solubility of silver chromate in moldm^-3 at this temperature.

           Ag₂CrO₄----->2Ag²⁺+CrO₄^2-
Ratio = 1:2:1

Ksp = [Ag²⁺]³
cube root of 1.00x10^-12 = 1x10^-4 for chromate.
2x1x10^-4 = 2 x10^-4 for Ag²⁺ multiply this by 2

[AS-Girl]

Another question...i know i made all of u teird from my questions!!

25. If the solubility product (Ksp) for lead oxalate (PbC2O4) is equal to 8.5 x 10-9,
what is the molar solubility of a saturated solution of lead oxalate?

(a) 8.5 x 10+9 mole / liter (c) 9.2 x 10-5 mole / liter
(b) 9.2 x 10+5 mole / liter (d) 8.5 x 10-9 mole / liter

??:S :S

[Haaks18]

Is This Chemistry AS edexcel :/

[Amelia]

Another question...i know i made all of u teird from my questions!!

25. If the solubility product (Ksp) for lead oxalate (PbC2O4) is equal to 8.5 x 10-9,
what is the molar solubility of a saturated solution of lead oxalate?

(a) 8.5 x 10+9 mole / liter (c) 9.2 x 10-5 mole / liter
(b) 9.2 x 10+5 mole / liter (d) 8.5 x 10-9 mole / liter

??:S :S

You have asked this question before(And Deadly_King had already solved it.). The only difference is that the question is the other way round.
https://studentforums.biz/sciences-149/chemistry-people-come-in!!/

@Haaks - I dont know, but I've answered your questions above.

[Haaks18]

Thanks for answering :p

[Deadly_king]

Is This Chemistry AS edexcel :/

Nope that is A2.

Good job daughter.

[Amelia]

Nope that is A2.

Good job daughter.

You just made me smile.

[AS-Girl]

here are 2 questions :

1) If the pH of a tomato juice is 4.50, then the hydroxide ion concentartion [OH]- of the juice is:
a) 3.16X 10^(-5) mole/litre
b)1.00X 10^(-14) mole/litre
c) 3.16X10^(-9) mole/litre
d) 1.00X 10^(-7) mole/litre


2)How many ions per formula unit would you find if you dissolve (NH4)2[Ce(NO3)6] in water?
a) 3
b)9
c) 2
d) 6


Thanks in advance

[tmisterr]

here are 2 questions :

1) If the pH of a tomato juice is 4.50, then the hydroxide ion concentartion [OH]- of the juice is:
a) 3.16X 10^(-5) mole/litre
b)1.00X 10^(-14) mole/litre
c) 3.16X10^(-9) mole/litre
d) 1.00X 10^(-7) mole/litre


2)How many ions per formula unit would you find if you dissolve (NH4)2[Ce(NO3)6] in water?
a) 3
b)9
c) 2
d) 6


Thanks in advance

1. hmm, i'm getting an answer not included in the choices......Since pH is -log[H+], we need to un-log the pH value to find the hydrogen ion concentration. which is 10^-4.5= 3.16x10^-5. since the tomato juice is in aqueous form and we know the ionic product of water (assuming it is at rtp its value is 1x10^-14), we can use it to find the hydroxide ion concentration. Kw=[H+]*[OH-] so [OH-]=Kw/[H+] which is 1x10^-14/3.16x10^-5=3.16x10^-10

2. it will dissolve into 2NH4+ and the complex ion [Ce(NO3)6]2- where NO3 is the ligand, assuming that it completely dissociates. so 2 ammonium ions and one complex ion to give a total of 3 ions per unit formula so a is your answer