Home
Class 11
CHEMISTRY
When hydrochloric aicd is addded to coba...

When hydrochloric aicd is addded to cobalt and nitrate solution at room temperautre, the following reaction takes place and the reaction mixture becomes blue. On cooling the mixture it becomes pink. On the basis of this information mark the corect ansewer.
`underset("pink")[[Co(H_(2)O)_(6)]]^(3+)(aq)+4CI^(-)hArr`
`underset("blue")[CoCI_(4)]^(2-)(aq)+6H_(2)O(l)`

A

`DeltaH gt0 ` for the reaction

B

`DeltaH lt0 ` for the reaction

C

`DeltaH =0 ` for the reaction

D

The sign of `DeltaH `cannot be predicted on the basis of this information

Text Solution

Verified by Experts

The correct Answer is:
A
In the reaction, `underset(("Pink"))([Co(H_2O)_(6)]^(3+))(aq) +4Cl^(-) (aq) hArr underset(("Blue"))([CoCl_4]^(2-))(aq)+6H_2O(l)`
On cooling, the equilibrium shifts backward direction or on heating, the equilibrium shifts forward direction.
Hence, reaction is endothermic. i.e., `DeltaH gt 0`
Promotional Banner

Similar Questions

Explore conceptually related problems

Assertion (A) : On cooling in a freezing mixture, colout of the mixture turns to pink from deep blue for a reaction. underset(("Pink"))(Co(H_(2)O)_(6)^(2+))(aq)+4CI^(Theta)hArr underset((Blue))(CoCI_(4)^(2-)(aq))+6H_(2)O(l) Reason (R) : The reaction is endothermic in formed reation, so on cooling the reaction, deep blue colour appears.

Assertion : On cooling a freezing mixture, color of the mixture turns to pink from deep blue for a reaction. Co(H_(2)O)_(6)^(2+)_(aq) + 4Ci^(-)_(aq) hArrCoCI_(4)^(2-)(aq) + 6H_(2)O_((l)) . Reason : Reaction is endothermic so on cooling, the reaction moves to backward direction.

Which of the following expression is correct for the rate of reaction given below ? 5Br^(-)(aq) + BrO_(3)^(-)(aq) + 6H^(+) (aq) to 3Br_(2) (aq) + 3H_(2) O(l) .

The organic product formed in the reaction C_(6)H_(5)CO OH overset(1. LiAlH_(4))underset(2. H_(2)O^(+)) to

CoCl_(4)^(2-)(aq) is blue in color while [Co(H_(2)O)_(6)]^(2+) is pink. The color of reaction mixture Co(H_(2)O)_(6)^(2+)(aq)+4Cl^(-)(aq)hArr CoCl_(4)^(2-)(aq)+6H_(2)O(l) is blue at room temprature while it is pink when cooled heance