Solutions

When an electrolyte dissociates in a solution, number of particles increases and

van't Hoff factor (i)


for dissociation

Osmotic pressure is directly proportional to the temperature where,

• C= concentration
• R= gas constant
• T= temperature

i.e. , thus, on increasing the temperature, osmotic pressure also increases.

Discover More From Chapter: Solutions

The reaction between acidified potassium dichromate ( ) and iodide ions ( ) in acidic solution involves the reduction of to , while is oxidized to iodine ( ). The balanced equation for the reaction is: From the equation, it is clear that 1 mole of liberates 3 moles of . To liberate 6 moles of , we need: Thus, 2 moles of are required to liberate 6 moles of .

The correct option is (B) : 2

Correct Answer: 0.1

Explanation:
To find the mole fraction of water, we use the formula:
Mole fraction of water (χ_water) = moles of water / (moles of water + moles of alcohol)

Given:
• Mass of water = 18 g
• Molar mass of water (H₂O) = 18 g/mol → Moles of water = 18 / 18 = 1 mol

• Mass of ethyl alcohol (C₂H₅OH) = 414 g
• Molar mass of ethyl alcohol = 46 g/mol → Moles of alcohol = 414 / 46 ≈ 9 mol

Now, mole fraction of water:


Therefore, the mole fraction of water is 0.1.

Oedema, or swelling, occurs when fluid accumulates in the body's tissues. This can happen due to various reasons, including prolonged sitting, which can reduce blood and lymph flow, leading to fluid buildup.

Soaking the feet in warm salt water can help reduce this swelling. The warmth of the water increases blood flow, while the salt (sodium chloride) in the water helps draw fluid out of the tissues.

Analyzing the Options

1. (A) Reverse Osmosis
   Reverse osmosis is a process where water is forced through a semipermeable membrane to remove contaminants. This is not the mechanism by which salt water reduces swelling.
2. (B) Osmosis
   Osmosis is the movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. The salt in the water increases the solute concentration outside the cells, drawing water out of the cells and reducing swelling.
3. (C) Edema
   Edema is the condition of swelling, not the process by which it is reduced.
4. (D) Diffusion
   Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration. While diffusion plays a role in many biological processes, it is not the primary mechanism by which soaking in salt water reduces swelling.

Conclusion

The correct answer is (B) Osmosis. Soaking the feet in warm salt water reduces swelling by increasing the solute concentration outside the cells, which draws water out of the cells through osmosis.

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:

The colloidal particles of Fe(OH)₃ are surrounded by water molecules and hydroxide ions. Therefore, sol X is represented as:

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:

In excess NaOH, Fe(OH)₃ dissolves to form the soluble ferrate complex, and sol Y is represented as:

Conclusion:

The correct matching of sol X and sol Y is: - Sol X: - Sol Y: Therefore, the correct answer is Option (D).

Correct Answer: Option (D)

Dimerisation of solute molecules in solvents with a low dielectric constant occurs predominantly due to hydrogen bonding.

Detailed Explanation:

• (A) Hydrogen bond: Correct Answer. In solvents with low dielectric constants, intermolecular hydrogen bonds become stronger due to the reduced solvent polarity, leading to the formation of stable dimers. This phenomenon is typical in carboxylic acids (e.g., acetic acid dimerisation in benzene).
• (B) Covalent bond: Incorrect. Covalent bonds involve electron sharing within molecules, not between distinct molecules in solution under these conditions.
• (C) Co-ordinate bond: Incorrect. Coordinate bonds involve electron donation from one species to another, usually seen in complex formation, not typical for dimerisation in low dielectric solvents.
• (D) Ionic bond: Incorrect. Ionic bonds generally require solvents with high dielectric constants (like water) for ion stabilization and dissociation. They are not favored in solvents with low dielectric constants.

Conclusion:

The correct answer is Option (A): Hydrogen bond.

To solve this problem, we need to determine the solubility of calcium oxalate ( ) in pure water given its solubility product, , at a certain temperature.

The solubility product expression for in water is given by:

Since dissociates as follows:

Let be the solubility of in mol/L. Then, at equilibrium:

Therefore, the expression for the solubility product becomes:

Given that , we find:

Solving for :

Upon reviewing the options provided, I realized there's a discrepancy with the given correct answer. The calculated solubility is , which matches the second option.

Therefore, the solubility of at this temperature is . The provided correct answer might need to be reviewed, as the calculated result is different.

To determine the vapour pressure of the solution containing glucose and water at 100°C, we can use Raoult's Law. According to Raoult's Law, the vapour pressure of a solution is the product of the mole fraction of the solvent and the vapour pressure of the pure solvent. Mathematically, it is given by:

Where:

• is the vapour pressure of the solution.
• is the mole fraction of the solvent (water).
• is the vapour pressure of pure water at 100°C, given as 760 torr.

First, we need to calculate the moles of glucose and water:

• Molar mass of glucose (C₆H₁₂O₆): 180 g/mol
• Moles of glucose:
• Molar mass of water (H₂O): 18 g/mol
• Moles of water:

Now, calculate the mole fraction of water:

Using Raoult's Law, calculate the vapour pressure of the solution:

Considering significant figures and rounding, the vapour pressure of the solution is approximately 752.0 torr.

Hence, the correct answer is: 752.0 torr.

To determine which pair will show positive deviation from Raoult's Law, we need to understand what Raoult's Law is and what positive deviation implies.

Raoult's Law states that the vapor pressure of an ideal solution is directly proportional to the mole fraction of the solvent present in the solution. In a solution showing positive deviation from Raoult's Law, the observed vapor pressure is higher than predicted by Raoult's Law. This occurs when the interactions between unlike molecules are weaker than those among like molecules, leading to greater tendency for evaporation.

Let's analyze each pair:

1. Water - HCl: This is a strong acid solution where hydrogen bonding occurs significantly between the components. Typically, this pair would show negative deviation due to strong intermolecular attractions.
2. Benzene - Methanol: Methanol can hydrogen bond, while benzene is non-polar and cannot hydrogen bond. The interaction between methanol and benzene is weaker than the hydrogen bonding between methanol molecules, leading to positive deviation.
3. Water - : Like water and HCl, water and nitric acid form a strong acid solution with significant hydrogen bonding, generally resulting in negative deviation.
4. Acetone - Chloroform: This pair commonly shows negative deviation from Raoult’s Law due to the presence of hydrogen bonding between chloroform and acetone, which is stronger than within the pure components.

Therefore, the correct answer is Benzene - Methanol, as the intermolecular forces between methanol and benzene are weaker than the forces within pure methanol, leading to positive deviation from Raoult's Law.

To solve the question of identifying the value of 'A' in the given equation , we need to understand the Kohlrausch's Law of Independent Migration of Ions.

This law states that the molar conductivity of an electrolyte at infinite dilution (i.e., when the concentration approaches zero) is equal to the sum of the ionic conductivities of the cations and anions. In this context, the equation can be interpreted for comparing the molar conductivity at infinite dilution for different ionic compounds, denoted as , and its relationship with concentration .

In the given options:

• NaCl and CaCl₂ - These are different types of ions with different charges, and their constant 'A' would differ due to ionic size and interaction differences.
• CaCl₂ and MgSO₄ - Again, these have different cationic compositions and charge differences.
• NaCl and KBr - Both are halide salts with the same type of anions, similar ionic radii, and similar cationic charge (+1), hence they are expected to have the same 'A' value due to comparable ionic mobility.
• MgCl₂ and NaCl - Different charge states and ionic interactions.

The constant 'A' is the ion-specific parameter that reflects the ion's effect on molar conductivity. When comparing NaCl and KBr, both have monovalent cations (Na⁺ and K⁺) and monovalent anions (Cl^- and Br^-), which leads to the same influence on the molar conductivity in the equation, making 'A' the same for them.

Considering these explanations, the correct answer is NaCl and KBr because they both have similar ionic characteristics and behavior in a solution that affects the parameter 'A' equally.