Question

write down the name of metal iron, lead calcium in order of decreasing metallic activity. justify your order by comparing: (i) Their reaction with water or steam giving equation where possible (ii) their behaviour when heated with air or oxygen (ii) the behaviour of their oxide when heated in hydrogen or coal gas. ​

Answer 1

Answer:

Solution : 

This reaction can be written in the form of a word equation as: 

Iron+Steam→Iron(II,III)oxide+HydrogenIron+Steam→Iron(II,III)oxide+Hydrogen 

Now, Symbol of iron is fe 

Formula of steam isH2O (It is the same as water)Formula of steam isH2O (It is the same as water)

Formula or iron (II,III) oxide isFe3O4 (Given)Formula or iron (II,III) oxide isFe3O4 (Given) 

And, Formula of hydrogen is H2H2 

By writing the symbols and formulae of all the substances in the above word equation, we get the following skeletal chemical equation: 

 Fe+H2O→Fe3O4+H2Fe+H2O→Fe3O4+H2 

Here Fe and H2OH2O are reactants whereas Fe3O4andH2Fe3O4andH2 are the products. Let us count the number of atoms of various types in the reactants and products : 

No . of Fe atoms:No . of H atoms:No . of O atoms:In reactants121In products324In reactantsIn productsNo . of Fe atoms:13No . of H atoms:22No . of O atoms:14 

We can see that the number of iron atoms on the left side of the equation is only 1 but there are 3 iron atoms on the right side. Now, to have 3 iron atoms on the left side, we multiply Fe by 3 and write it as 3Fe. Thus, 

 3Fe+H2O→Fe3O4+H23Fe+H2O→Fe3O4+H2 

Let count the number of various types of atoms on both the sides again : 

No . of Fe atoms:No . of H atoms:No . of O atoms:In reactants321