chemistry p1 help!! plz.

[paparazzi]

mj 03
Q2,Q8,Q20,Q27.

Any 1 plz.....really need ur help///

 

[ashhadazam]

For Question 2 juss count how many H are being added.. For the first side chain 2 H are added.. For the second and third 4 are added.. A total of 10.. so u need 5 moles of Hydrogen to hydrogenate this horrible compound into soft margarine !

 

[ashhadazam]

For Q.8) The ans is A .. In ammonia the oxidation state of N is -3 .. in NO it is +2 .. so a total difference of 5 which is greatest among all the compunds given

 

[ashhadazam]

Q.20) 7 isomers in total.. the trick of doing such type of questions is to identify all the cis-trans isomers first then proceed on finding structural isomers..

There are in total 4 cis-trans isomers possible in this compond.. 2 wid Cl and 2 with H ..

5th isomer is structural wid both Cl atoms on the double bonded carbon..
6th isomer is structural with both H atoms bonded to double bonded carbon and the third H also bonded to adjacent carbon
7th isomer is structural with both H atoms bonded to double bonded carbon and the Cl atom bonded to adjacent carbon

 

[ashhadazam]

Q.27) its C.. because in CFCS only chlorine breaks down to form radicals , i.e no loss of fluorine or hydrogen.. Only option C satisfies this condition

 

[beacon_of_light]

mj 03
Q2,Q8,Q20,Q27.

Any 1 plz.....really need ur help///

Q2: Ve know that 1 mole of hydrogen is required for one double bond. Now as the question says, one side chain (first one) with two double bonds changes to one with 1* double bond. So the decrease in double bonds is 1 and one mole of hydrogen is required.

Now for the nxt 2 side chains, there are six total double bonds. each side chain after conversion has 1 double bond present. so in total ,for the conversion of two side chains 2 double bonds will be left, that means 4 double bonds have gone. Thus, the total moles of hydrogens required is 1+4= 5..........a simple question buh required hell of looong explanation!!

nxt question ...q8
calculate the oxidation state of N in every compound and then compare...in A, N changes from -3 to +2...that is the largest change in oxidation state...

Q20: here are the structural isomers formed...
1,1-dichloro propene
1,2-dichloropropene
2,3-dichloropropene
1,3-dichloropropene
3,3-dichloropropene

and 2 geometric isomers( cis-trans) will be formed...in total 7 isomers formed!!!

last question...
This compound is CFC and in the upper atmosphere by irradiation , C-Cl bond will break since it is the weakest of all....And only in C this bond breaks!!!

Hope you get that!!!

 

[paparazzi]

sorry 2 bother u guys again...
can sum1 tell me how to do mj02 QS 11,13,30 AND Q 39 why between X and Y the C-Hal bond will be lengthening.

mj 04 QS 9.

REALLY APPRECIATE OF UR HELP!!!!

 

[beacon_of_light]

q11: The rate of reaction here depends on the formation of products...in the beginning of a reaction, formation of produtcs is higher due to excess of substrate but as the reaction continues, rate of formation of product is reduced as reactants are used up...curve C best explains this choice!

q13: What do you think will an alkali dissolve an alkali??? No way...So only MgO is the right choice since it is a basic oxide or a weak base like CaO.

q30: Acid Hydrolysis of an ester produces the corresponding carboxylic acid and alcohol. here, HCOOH and RCH(CH3)OH will be produced! I hope you know the rules of hydrolysis as in which alcohol or carboxylic acid will be produced!

q39: In a nucleophilic substitution reaction, when one nucleophile is replaced by another nucleophile, the leaving nucleophile's bong length with C must decrease(that is the bond must lengthen)...so that the attacking nucleophile can take its place by forming a strong bond with C. And v know longer bonds are weaker bonds while shorter bonds are stronger bonds....

Hope that clarifies your confusions

 

[beacon_of_light]

may /june04 ..q9

Now when an acid dissociates, it produces H+

So if an acid has a conc. of 1 mol/dm^3, and it produces 1 mol of H+, the conc of H+ will be 1mol/dm^3, but if for example sulphuric acid dissociates, it produces 2 H+...which means H+ conc doubles...that is 2mol/dm^3....So the correct answer is HNO3..which is a monoprotic acid..that is it produces 1 H+ in water...

 

[paparazzi]

q11: The rate of reaction here depends on the formation of products...in the beginning of a reaction, formation of produtcs is higher due to excess of substrate but as the reaction continues, rate of formation of product is reduced as reactants are used up...curve C best explains this choice!

q13: What do you think will an alkali dissolve an alkali??? No way...So only MgO is the right choice since it is a basic oxide or a weak base like CaO.

q30: Acid Hydrolysis of an ester produces the corresponding carboxylic acid and alcohol. here, HCOOH and RCH(CH3)OH will be produced! I hope you know the rules of hydrolysis as in which alcohol or carboxylic acid will be produced!

q39: In a nucleophilic substitution reaction, when one nucleophile is replaced by another nucleophile, the leaving nucleophile's bong length with C must decrease(that is the bond must lengthen)...so that the attacking nucleophile can take its place by forming a strong bond with C. And v know longer bonds are weaker bonds while shorter bonds are stronger bonds....

Hope that clarifies your confusions

thx.!!!!!
a little bit confusion abt QS11, i think the products catalyses the reaction means it is a catalyst.but the definition for catalyst is a chemical substance which speeds up a chemical reaction w/o being used up. so why the reactants are used up??????

 

[paparazzi]

may /june04 ..q9

Now when an acid dissociates, it produces H+

So if an acid has a conc. of 1 mol/dm^3, and it produces 1 mol of H+, the conc of H+ will be 1mol/dm^3, but if for example sulphuric acid dissociates, it produces 2 H+...which means H+ conc doubles...that is 2mol/dm^3....So the correct answer is HNO3..which is a monoprotic acid..that is it produces 1 H+ in water...

what abt sodium hydroxide??? i think it also produces 1 H+ in h2o....

 

[beacon_of_light]

yeah listen....

In the beginning , as the reactants react, the products formed catalyse the reaction.therefore, reaction rate increases.A point is reached whereby rate of reaction decreases due to excessive depletion of the reactants ...as opposed to catalytic effect of the product!!! So thereby, rate decreases ......

 

[beacon_of_light]

may /june04 ..q9

Now when an acid dissociates, it produces H+

So if an acid has a conc. of 1 mol/dm^3, and it produces 1 mol of H+, the conc of H+ will be 1mol/dm^3, but if for example sulphuric acid dissociates, it produces 2 H+...which means H+ conc doubles...that is 2mol/dm^3....So the correct answer is HNO3..which is a monoprotic acid..that is it produces 1 H+ in water...

what abt sodium hydroxide??? i think it also produces 1 H+ in h2o....

hey, NaOH produces OH- in water!!!!!!!!!!!!!!!

 

[beacon_of_light]

may /june04 ..q9

Now when an acid dissociates, it produces H+

So if an acid has a conc. of 1 mol/dm^3, and it produces 1 mol of H+, the conc of H+ will be 1mol/dm^3, but if for example sulphuric acid dissociates, it produces 2 H+...which means H+ conc doubles...that is 2mol/dm^3....So the correct answer is HNO3..which is a monoprotic acid..that is it produces 1 H+ in water...

what abt sodium hydroxide??? i think it also produces 1 H+ in h2o....

hey, NaOH produces OH- in water!!!!!!!!!!!!!!!

 

[Xenon]

I need help with nov 09, q31, variant 11

 

[paparazzi]

yeah listen....

In the beginning , as the reactants react, the products formed catalyse the reaction.therefore, reaction rate increases.A point is reached whereby rate of reaction decreases due to excessive depletion of the reactants ...as opposed to catalytic effect of the product!!! So thereby, rate decreases ......

yeah.thank u~

 

[beacon_of_light]

I need help with nov 09, q31, variant 11

if all the monomers string together to make one chain, then you've got one molecule, which is 1/6E23 of a mole.


Any number between that and 1 is theoretically possible, so 1E-06 should be possible.

 

[Xenon]

I need help with nov 09, q31, variant 11

if all the monomers string together to make one chain, then you've got one molecule, which is 1/6E23 of a mole.


Any number between that and 1 is theoretically possible, so 1E-06 should be possible.

Thanks, now I get it.

 

[paparazzi]

why an element can have different oxidation no.?
e.g Cl,N,S ????
AND why not beryllium have same oxidation no in all of its known compounds?

 

[beacon_of_light]

Just rattafy that ...but yeah there is a point, different oxidation states arise due to filling of d-orbitals...But in As you do not need details!!!