Chemistry: Post your doubts here!

[snowbrood]

The greater the difference in the electronegativity the more polar the bond is

why are u comparing SE with O and S with O why not SE with S this would easier for me to understand why complicate

 

[Muhammad Bin Anis]

why are u comparing SE with O and S with O why not SE with S this would easier for me to understand why complicate

SE and S both are bonded to O . You consider the the electronegativity difference between both the cases.

 

[unseen95]

i didn't receive answers to two questions and the questions are making me crazy

 

[Malik777]

View attachment 23074
Can you answer this also please? Its from the same year and variant is 13.

A

 

[Malik777]

A

As HSO3 -1 is conjugated base of SO2 what's the answer?

 

[Tkp]

can someone explain me x ray crystallography

 

[gary221]

can someone explain me x ray crystallography

Have u tried chemguide??
http://www.chemguide.co.uk/CIE/section112/learninge.html

 

[lyuchenqujoy]

Can anyone explain to me why change in pressure won't affect equilibrium constant?

 

[A*(a*)]

As HSO3 -1 is conjugated base of SO2 what's the answer?

thanks Yes A is the answer, another forum member told me that in eq1 H2SO3 forms which decomposes to products stated, this is correct i guess .

 

[salvatore]

Can anyone explain to me why change in pressure won't affect equilibrium constant?

Equilibrium constant does not change when you change the pressure of a system. The only factor that affects the equilibrium constant is temperature.
The equilibrium constant is just a ratio of the product of the products to the product of the reactants.. right? Now increasing the pressure of the reactant unbalances the equilibrium because more products are formed. The concentration of products will increase until a new equilibrium is reached when the value of the equilibrium constant gets back to what it was before (The value remains the same).

In conclusion, the equilibrium "constant" is always constant unless the pressure is changed.

 

[Tkp]

aha thanks

Have u tried chemguide??
http://www.chemguide.co.uk/CIE/section112/learninge.html

 

[Adorkableme]

Hi, I need someone to explain the mechanism for addition oxidation of alkenes. My teacher told me a different mechanism then the one shown in the notes section of XP.....and I am confused between the two....
If someone could give me a step by step explanation of exactly what happens that would be very helpful....

 

[mariyam95]

And can anyone on Earth tell me what am I missing in this question?
The refrence is 9701/12/M/J/11 [ U can check the markscheme, the answer is A. How is 1 correct ?!!!
View attachment 23077

nitrogen is been reduced because see the oxidation number of nitrogen in NCl3 nitrogen oxidation number is +3 and nitrogen oxidation number in N2 is 0 therefore nitrogen has gained electrons and we know that gaining electrons is reduction

 

[mariyam95]

O/N 11/12 question 3
Can anyone who is good in chemistry solve this?
Use of the Data Booklet is relevant to this question.
From which particle is the removal of an electron the most difficult?
A Cl- (g) B F- (g) C K+ (g) D Na+ (g)

check out the ionisation energy values the element which has the highest value .. so d is the answer because Na+ has the highest value

 

[Nidz-Ahmed]

The reaction of hydrogen sulphide with sulfur dioxide gives sulphur as one of the products. h
H2S(aq) < -------> 2H2+(aq) +2e+S(s)
SO2(aq)+ 4H2+4e< -------> S(s) +H2O
how many moles of hydrogen sulphide are neede to react with sulphur dioxide to produce 1mole of sulphur ?
Help?
a- 1/3 mol
b-2/3 mol
c-3/2 mol
d-2 mol

 

[sumaiyarox:)]

8 (a) Electrophoresis can be used to separate amino acids which are produced by the
hydrolysis of a polypeptide.
Using glycine as an example, explain why the result of electrophoresis depends on pH.
qp so7
sm1 plz state d logic

 

[Muhammad Bin Anis]

The reaction of hydrogen sulphide with sulfur dioxide gives sulphur as one of the products. h
H2S(aq) < -------> 2H2+(aq) +2e+S(s)
SO2(aq)+ 4H2+4e< -------> S(s) +H2O
how many moles of hydrogen sulphide are neede to react with sulphur dioxide to produce 1mole of sulphur ?
Help?
a- 1/3 mol
b-2/3 mol
c-3/2 mol
d-2 mol

i think the answer should be D i.e 2 moles

 

[Muhammad Bin Anis]

8 (a) Electrophoresis can be used to separate amino acids which are produced by the
hydrolysis of a polypeptide.
Using glycine as an example, explain why the result of electrophoresis depends on pH.
qp so7
sm1 plz state d logic

check the marking scheme .. the explanation is given

 

[sumaiyarox:)]

check the marking scheme .. the explanation is given

cmon ofcourse ichecked d mark scheme..!! ididnt get a wrd..!!pchhh...nai smajh ra he...

 

[Muhammad Bin Anis]

cmon ofcourse ichecked d mark scheme..!! ididnt get a wrd..!!pchhh...nai smajh ra he...

chalo i am giving it a try

amino acids contain the -NH2 group . when the solution is acidic (i.e H+ ions are present), nitrogen in the the -NH2 group uses iits lone pair of electrons and attracts the H+ ion.. a dative covalent bond is formed and the charge on the molecule is is increased by +1 so the spot moves towards the negative electrode(cathode)

in case the solution becomes more alkaline, the COOH ggroup loses its hydrogen in the form of H+ ions to nuetralise the ffect of base (OH- ions and H+ ions react to form water)
but the charge on the original molecule has decreased by 1 , it is attarcted to the anode (pos. electrode)

This way electrophoresis is dependant on the pH