Metal problem

From the metals Mg and Fe, select a different metal in each case-
a) Does not react with dil hydrochloric acid
b) Does not react with cold water but reacts with steam when heated....

This question came in my school chemistry exam....
Thanx in advance...

5 Answers

269
Astha Gupta ·

if u go through the reactivity series, u will find that Mg is still higher in the reactivity series than Fe. Actually both the metals react with dil. HCL, but Fe is less reactive than Mg, so, comparatively Fe will react less than Mg...so for (a)....the answer should be Fe...and in case of (b)...its obviously Fe....it always tract with hot steam....
i hope it answers the questions...

337
Sayan Sinha ·

I had marked (a) as Fe and (b) as Mg...
But my marks were deducted. They said (a) should be Mg and (b) should be Fe...
I don't understand why...

269
Astha Gupta ·

ammm....see..the second 1 is obviously Fe...the first 1 would have been Fe 2...but...sometimes..u cannot argue did the teachers...let it be..

337
Sayan Sinha ·

Accoding to you, why can't the second one be Mg?

269
Astha Gupta ·

second one cannot be Mg bcoz since its reactivity is more it does not require that much of kinetic energy to react. Cold water is enough to exaggerate its electrons and react spontaneously. for Fe i can say that Fe is not that reactive. So to make it react, we will require some more energy in the form of heat. that's why it reacts with hot steam only. this is the possible and the easiest explanation that i have.
if i go in some more detail than i can only tell u about the orbitals of Fe, i.e. 1s2 2s2 2p6 3s2 3p6 4s2 3d6, which makes a strong bond and makes it difficult for Fe to loose its electrons, hence decreasing its reactivity.

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