Question

FesCN (aq), and LeChâtelier's Explain in terms of the equation, Fe" (aq) + SCN (aq) Principle (4 ) Observation after adding KSCN: turned darker more red like original solution brown Explain in terms of the equation, Fe (aq) + SCN (aq) + FeSCN- (aq), and LeChâtelier's Principle. (ps.) Observation after adding AgNO3: Turned milky white + thieverf less transparent Using the ions present in the solution, write a net ionic equation that would explain the precipitate observed Use the above equation and Fe" (aq) + SCN (aq) terms of LeChâtelier's Principle. pes.) FeSCN (aq) to explain the observations in Observation after adding NaOH: turned to a light yellow ish orange HIILITEIT Using the ions present in the solution, write a net ionic equation that would explain the precipitate observed. Use the above equation and Fe (aq) + SCN (aq) terms of LeChatelier's Principle. pts) FeSCN" (aq) to explain the observations in

Answer 1

Let's consider the reaction: $A+B\rightleftharpoons C$

According to Le Chatelier's principle, adding reactants (A, B) in the reaction mixture shifts the equilibrium to the right, or in other words, more product C is formed. Similarly, the addition of product (C) shifts the equilibrium towards the reactant side.

     Reaction: $Fe^{3+}+SCN^{-} \rightleftharpoons FeSCN^{2+}$

                   (colorless)                  (colored)

1. After adding KSCN, the solution becomes darker because more FeSCN²⁺ is formed according to Le Chatelier's principle.

2. After adding AgNO₃, it turns milky white.

$AgNO_3+SCN^{-} \rightleftharpoons AgSCN\downarrow +NO_3^{-}$

Equilibrium shifts towards the left, thus breaking down the product into colorless Fe³⁺, SCN^- ions.

3. The addition of NaOH turns the solution light yellowish-orange.

$Fe^{3+}+3 NaOH \rightleftharpoons Fe(OH)_3 \downarrow+3 Na^+$

Fe³⁺ is removed by precipitation of light yellowish-orange colored Fe(OH)₃.

Reaction: Copper (II) nitrate +ammonia

$NH_3+H_2O\rightleftharpoons NH_4^++OH^-$

In aqueos solution, Copper(II) exists as

$Cu(H_2O)_6^{2+}$

Addition of a small amount of ammonia (ammonia acts as a base):

$Cu(H_2O)_4(OH)_2$

Addition of excess amount of ammonia (acts as ligand exchanger):

$Cu(NH_3)_4(H_2O)_2^{2+}$

The addition of strong acid like HNO₃:

$H^++NH_3\rightleftharpoons NH_4^+$

According to Le Chatelier's principle, removal of NH₃ causes the destruction of the complex, thus setting the Cu²⁺ ions free. At the same time, ammonia gets released from the complex.