on heating green coloured ferous sulphate crystal  reddish brown solid is left and smell of a gas having odour of burning sulphur is absorbed ?

why is the amount of a gas collected in one of the test tube in activity 1.7 double of the amount collected in other. name these gases?

give five example of ridox reaction?

during the reaction of some metal with dilute hydrochloride following observations were make:

the temperature of the reaction rises when aluminium is added.

the reaction of sodium metal is found to be highly explosive.

some bubbles of a gas  are seen when lead is reacted with the acid

Asked by himanshitanda2605 | 30th May, 2019, 01:21: PM

Expert Answer:

(a) This an example of a thermal decomposition reaction.
(b) This is because the formula of water is H2O, so the volume of hydrogen produced is twice the volume of oxygen produced.

(c) Example of redox reaction: 
H2S + Cl2 → 2HCl + S 

The O.N. of S increases from -2 to 0. So it is undergoing oxidation and O.N. of Cl2 decreases from 0 to -1. So it is undergoing reduction. Therefore it is a redox reaction.

CuO + H2 → Cu +H2O

In this redox reaction, CuO is getting reduced to Cu since Oxygen is getting removed. So, the conversion of CuO to Cu is a reduction reaction. H2 is getting oxidised to H2O. So, it is an oxidation reaction.

Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s)

Thr oxidation state of Fe changes from 0 to +2 and oxidation state of Cu changes from +2 to 0.

MnO4-+ I- → MnO2 + I2

Here I- is oxidised to I2 and MnO4 - is reduced to MnO2.

Pb + PbO2 + 2H2SO4 → 2PbSO4 + 2H2O

In this reaction, Pb is getting oxidised to PbSO4 and PbO2 is reduced to PbSO4.

     (i)  because the reaction of aluminium with hydrochloric acid is an exothermic reaction
     (ii) as sodium is a very reactive element so it reacts vigorously with HCl and is found to be explosive
    (iii) bubbles of hydrogen gas  are seen when the lead is reacted with the acid

Answered by Ramandeep | 30th May, 2019, 02:53: PM