26th December 2008

90 gm of a metal reacts with 80 gm of oxygen to form metal oxide. The metal oxide requires 20 litre of 1/3 N of oxidizing agent to oxidise to M5+. The molecular weight of the metal is

22 Answers

1357
Manish Shankar ·

Its "27"

1
Siddharth S ·

Gr8 solution.

1
gagar.iitk ·

manish is it really neccessary to assume the molecular formulae of the metal oxide to be M2Ox type only i am getting the same ans by taking MxOy type i think question dont state that ....

33
Abhishek Priyam ·

hmmmmmmmmmmmm

1357
Manish Shankar ·

M +O2→M2Ox→M5+

From definition, equivalent weight is defined as the weight of metal which combines with 8 g of oxygen.

so the equivalent weight of metal is 90/10=9

grameq. of metal=10

gram eq. of metaloxide in first reaction is 10
gram eq. of metaloxide in second reaction is 20/3

But moles of metaloxide will remain same in first as well as second reaction
n1=n2
geq/x1=geq/x2

10/(2*x)=(20/3)/(2*(5-x))
x=3

M=E*x=9*3=27

33
Abhishek Priyam ·

[7][7]

33
Abhishek Priyam ·

Me getting 31 :(

1
skygirl ·

how 27 ?

1
skygirl ·

yaar tumlog subjective me kaise tukka marte ho ?

how i proceeded..

1) found no of equi (20/3)

2) M(90) + O(80) ---> MO(170)

so 80g has to 20/3 eq.

so, no of moles = 80/32 = 5/2 = 20/3 X n-factor
=> n = 3/8

now, 90/ M = 3/8 X 20/3 => M=36 g

is this the ans?

11
Anirudh Narayanan ·

Solution?

33
Abhishek Priyam ·

half waht aragorn guesssed and most near to me :P

but this was my first answer which i gave of chemsitry question after solving (in a test or here )

and got it wrong... :(

11
Anirudh Narayanan ·

55? Don't ask me fr reason. It's a classic tukkabaji[4]

33
Abhishek Priyam ·

[1]

1
skygirl ·

btw, wat is the correct ans ?

11
Anirudh Narayanan ·

Tukkabaji? [3]

1357
Manish Shankar ·

I knew what you were writing :P

33
Abhishek Priyam ·

So its hypothetical but how u replied before my question while i was writing the post u replied.. :)

33
Abhishek Priyam ·

Me getting 21.5 :(

but this should not be as there is no such metal :(

1357
Manish Shankar ·

Consider metal to be hypothetical one

11
Anirudh Narayanan ·

Yup. Saw +5, took it as Mn5+ and saw molecular mass of Mn and gave it as 55 [4]

33
Abhishek Priyam ·

Classic Tukkabaji :P

1
skygirl ·

am getting a queer ans.. ~5g .

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