The compound(s) formed upon combustion of sodium metal in excess air is(are)
(A)Na2O2
(B)Na2O
(C)NaO2
(D)NaOH
1Time soln.
A,C,D in excess of air mainly Na2O2 is formed .small amts of naO2 is also formed resulting in yellow coloration of NaO2 .[purre Na202 is white]
small amts of moisture is also present in air,leading tothe formation of NaOH.
maharahtr state textbooks also have the same answer
1(john showed it to me)...in ncert it says both post #5 + it also says that Na forms some amt of superoxide as well.. Now i am confused
9just saw BT theory
this was written :
Li forms mainly oxides
Na forms oxide but the Na+ field is too weak to prevent its conversion to peroxides but stong enough to prevent forming superoxides
K,Rb,CS mainly form superoxides
9all coaching insti agree on A B
D is not a correct ans (combustion means heat , hydroxide formed decomposes to oxide only )
62You guys know my chemistry expertise.. but as far as I know air means we have to consider moisture.
Have you heard this question? What happens if anhydrous copper sulphate is left in air?
1rahul
A n C i agree r correct but we can't take NaOH into account since here i think excess of air doesn't say that it has moisture so by we consider it as dry air
62[url=http://iitjee2009solutions.targetiit.com]Solution Key with Question Paper of 2009 IIT JEE[/url]
1LETS WAIT FOR FINAL JEE SOLUTIONS BY IITs...........NE IDEA WHEN THEY WILL BE OUT???????
1CORRECT ANSWERS ARE (A) AND (C)......................TODAY ITSELF I FOUND IN A RELIABLE SOURCE!!!!!!!!.............................BUT HOW CUM ALL BANSAL,FIITJEE AND BRILLIANT ARE SAYING SAME (A) AND (B)
1..in NCERT it says that superoxides can be formed only with K,Rb or Cs...
6well bhaiya sorry to share my thougts again:
Na + limited supply of oxygen -----------> Na2O2
this reaction takes place at a temperature of 300°C
Na + NaNo3 -------------> Na2O
this reaction also do not occur in presence of high oxygen supply as this will lead to the formation of NaO2
which only come to existence under these circumstances only!!!!!!!!
hence the answer should be only C
sources: J.D.Lee and FIITJEE RSM S block sheet!!!!!!!!
cheers!!!!!!!!
