When FeCl3 is added to excess of hot water gives a sol ‘X’. When FeCl3 is added to NaOH(aq) solution, gives sol ‘Y’.
X and Y formed in the above processes respectively are
X and Y formed in the above processes respectively are
- Fe2O3 . xH2O / OH- and Fe2O3 . xH2O/Fe3+
- Fe2O3 . xH2O / H+ and Fe2O3 . xH2O/Na+
- Fe2O3 . xH2O / Cl- and Fe2O3 . xH2O/OH-
- Fe2O3 . xH2O / Fe3+ and Fe2O3 . xH2O/OH-
The Correct Option is D
Approach Solution - 1
When FeCl₃ (ferric chloride) is added to hot water and NaOH, two different solutions are formed. Let's analyze both reactions:
Step 1: FeCl₃ added to hot water (giving sol X)
When FeCl₃ is added to hot water, it undergoes hydrolysis and forms a colloidal solution of ferric hydroxide (Fe(OH)₃) with a reddish-brown color. The reaction can be written as:
\[ \text{FeCl}_3 + 3\text{H}_2\text{O} \rightarrow \text{Fe(OH)}_3 \, \text{(colloidal)} + 3\text{HCl} \] The colloidal particles of Fe(OH)₃ are surrounded by water molecules and hydroxide ions. Therefore, sol X is represented as: \[ \text{Fe}_2\text{O}_3 \cdot x\text{H}_2\text{O} / \text{OH}^- \]
Step 2: FeCl₃ added to NaOH solution (giving sol Y)
When FeCl₃ is added to NaOH solution, the iron ions react with hydroxide ions to form ferric hydroxide (Fe(OH)₃), which dissolves in excess NaOH, forming a soluble complex ion. The reaction is:
\[ \text{FeCl}_3 + 3\text{NaOH} \rightarrow \text{Fe(OH)}_3 + 3\text{NaCl} \] In excess NaOH, Fe(OH)₃ dissolves to form the soluble ferrate complex, and sol Y is represented as: \[ \text{Fe}_2\text{O}_3 \cdot x\text{H}_2\text{O} / \text{Fe}^{3+} \]
Conclusion:
The correct matching of sol X and sol Y is: - Sol X: \(\text{Fe}_2\text{O}_3 \cdot x\text{H}_2\text{O} / \text{OH}^-\) - Sol Y: \(\text{Fe}_2\text{O}_3 \cdot x\text{H}_2\text{O} / \text{Fe}^{3+}\) Therefore, the correct answer is Option (D).
Correct Answer: Option (D)
Approach Solution -2
In the first process, when FeCl₃ is added to hot water, it undergoes hydrolysis, forming a colloidal solution of Fe₂O₃ . xH₂O. The Fe³⁺ ions are present in the sol, which forms a sol of hydrated ferric oxide. Thus, sol 'X' is Fe₂O₃ . xH₂O / Fe³⁺.
In the second process, when FeCl₃ is added to NaOH(aq), ferric hydroxide is formed, which also results in the formation of Fe₂O₃ . xH₂O in the sol, but this time the OH⁻ ions are present. This results in sol 'Y', which is Fe₂O₃ . xH₂O / OH⁻.
Thus, the correct answer is (D): Fe₂O₃ . xH₂O / Fe³⁺ and Fe₂O₃ . xH₂O / OH⁻.
Top Questions on Solutions
According to the generally accepted definition of the ideal solution there are equal interaction forces acting between molecules belonging to the same or different species. (This is equivalent to the statement that the activity of the components equals the concentration.) Strictly speaking, this concept is valid in ecological systems (isotopic mixtures of an element, hydrocarbons mixtures, etc.). It is still usual to talk about ideal solutions as limiting cases in reality since very dilute solutions behave ideally with respect to the solvent. This law is further supported by the fact that Raoult’s law empirically found for describing the behaviour of the solvent in dilute solutions can be deduced thermodynamically via the assumption of ideal behaviour of the solvent.
Answer the following questions:
(a) Give one example of miscible liquid pair which shows negative deviation from Raoult’s law. What is the reason for such deviation?
(b) (i) State Raoult’s law for a solution containing volatile components.
OR
(ii) Raoult’s law is a special case of Henry’s law. Comment.
(c) Write two characteristics of an ideal solution.- A solution of glucose (molar mass = 180 g mol\(^{-1}\)) in water has a boiling point of 100.20°C. Calculate the freezing point of the same solution. Molal constants for water \(K_f\) and \(K_b\) are 1.86 K kg mol\(^{-1}\) and 0.512 K kg mol\(^{-1}\) respectively.
- Define Azeotrope. What type of Azeotrope is formed by negative deviation from Raoult's law? Give an example.
- Give reasons:
(a) Cooking is faster in a pressure cooker than in an open pan.
(b) On mixing liquid X and liquid Y, volume of the resulting solution decreases. What type of deviation from Raoult's law is shown by the resulting solution? What change in temperature would you observe after mixing liquids X and Y? - An unripe mango placed in a concentrated salt solution to prepare pickle, shrivels because __________
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