Chemistry Solubility Concepts

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Questions and Answers

How does temperature affect the solubility of a solid in a liquid when the dissolution process is endothermic?

Solubility is not affected by the nature of the solute.

Solubility decreases with an increase in temperature.

Solubility remains unchanged with temperature changes.

Solubility increases with an increase in temperature. (correct)

Which of the following factors does NOT significantly affect the solubility of solids in liquids?

Pressure (correct)

Concentration of the solute

Temperature

Nature of the substances

What is the relationship between pressure and the solubility of gases in liquids?

Increasing pressure increases the solubility of gases. (correct)

Gases are always less soluble in liquids under high pressure.

Increasing pressure decreases the solubility of gases.

Pressure has no effect on the solubility of gases.

According to Le Chatelier's Principle, what will happen to the solubility of a solid if its dissolution process is exothermic and temperature increases?

Solubility decreases with a rise in temperature. Signup and view all the answers

Which of the following gases is known to be highly soluble in water?

Hydrogen chloride (HCl) Signup and view all the answers

What is the formula for calculating molality, m, of a solution?

$\frac{w_2 \times 1000}{M_2 \times w_1}$ Signup and view all the answers

If 18 g of glucose is dissolved in 1 kg of water, what is the value of w1?

1000 g Signup and view all the answers

What does $K_b$ represent in the context of the solution?

Boiling point elevation constant Signup and view all the answers

What is the significance of $\Delta T_b$ in the equations presented?

It is the change in boiling point of the solution. Signup and view all the answers

To determine the molar mass M2 of the solute, which of the following conditions must be satisfied?

DTb must be measured experimentally. Signup and view all the answers

What is the molar mass of acetic acid (C2H4O2)?

60 g mol–1 Signup and view all the answers

How many moles of C2H4O2 are in 2.5 g of the substance?

0.0417 mol Signup and view all the answers

What is the mass of benzene in kilograms if 75 g of benzene are used?

0.075 kg Signup and view all the answers

What does molality measure in a solution?

Moles of solute per kilogram of solvent Signup and view all the answers

Which of the following substances is least likely to dissolve in water?

Naphthalene Signup and view all the answers

What is the definition of solubility?

The maximum amount of solute that can dissolve in a solvent at specific conditions Signup and view all the answers

If 22 g of benzene is dissolved in 122 g of carbon tetrachloride, what needs to be calculated?

Mass percentage of both benzene and carbon tetrachloride Signup and view all the answers

What impact does temperature have on solubility?

It increases the mass of solute that can dissolve Signup and view all the answers

What is osmotic pressure dependent on?

The number of solute molecules in the solution Signup and view all the answers

According to the formula for osmotic pressure, P = CRT, what does 'C' represent?

The molarity of the solution Signup and view all the answers

What must be applied to a solution to prevent osmosis according to the definition of osmotic pressure?

An excess pressure Signup and view all the answers

Which of the following factors does NOT directly affect osmotic pressure in a dilute solution?

Nature of the solute Signup and view all the answers

In the equation P = (n2 / V) RT, what does 'n2' represent?

The number of moles of solute Signup and view all the answers

What can be calculated using the formula derived from osmotic pressure measurements?

Molar mass of the solute Signup and view all the answers

Why is the osmotic pressure method preferred for biomolecules?

Biomolecules are generally not stable at higher temperatures Signup and view all the answers

What characterizes two solutions that are isotonic?

They have the same osmotic pressure Signup and view all the answers

What is the significance of the quantity 'w2' in osmotic pressure calculations?

It is the weight of solute in grams Signup and view all the answers

What is a key advantage of using osmotic pressure to determine molar mass compared to other methods?

It works for very dilute solutions and is pressure dependent Signup and view all the answers

Study Notes

Solubility

Solubility is the maximum amount of a substance that can dissolve in a specific amount of solvent at a particular temperature.
Factors affecting solubility:
- Nature of solute and solvent: Some substances readily dissolve in water (e.g., sodium chloride, sugar), while others don't (e.g., naphthalene, anthracene).
- Temperature:
 - Endothermic dissolution (Dsol H > 0): Solubility increases with rising temperature.
 - Exothermic dissolution (Dsol H < 0): Solubility decreases with increasing temperature.
- Pressure: Pressure has minimal effect on the solubility of solids in liquids.
Solubility of gases in liquids:
- Gases have varying solubility in liquids (e.g., oxygen has limited solubility, while hydrogen chloride is highly soluble).
- Pressure: Solubility of gases increases with increasing pressure.
- Temperature: Solubility of gases decreases with rising temperature.

Colligative Properties

Colligative properties depend on the number of solute particles in a solution, not their nature or identity.
- Examples: Vapor pressure lowering, boiling point elevation, freezing point depression, osmotic pressure.
Boiling Point Elevation:
- The boiling point of a solution is higher than that of the pure solvent.
- Formula: ΔTb = Kb * m (where ΔTb is the boiling point elevation, Kb is the molal elevation constant, and m is the molality).
- Molality (m): Moles of solute per kilogram of solvent.
Osmotic Pressure:
- Definition: The pressure needed to prevent the flow of solvent across a semipermeable membrane into a solution.
- Formula: Π = CRT (where Π is osmotic pressure, C is molarity, R is the gas constant, and T is temperature).
- Advantages of using osmotic pressure to determine molar mass:
  - Measurements can be taken at room temperature.
  - Molarity, not molality, is used in the calculation.
  - Osmotic pressure is significant even for dilute solutions.
  - Useful for unstable molecules (like proteins and polymers) that degrade at higher temperatures or have poor solubility.
Isotonic solutions: Two solutions with the same osmotic pressure at a given temperature. No osmosis occurs between them.

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Description

This quiz covers the essential concepts of solubility, including factors that affect solubility such as the nature of solute and solvent, temperature effects, and the influence of pressure. Understand how colligative properties relate to solubility in different scenarios. Test your knowledge about the solubility of gases and solids in various conditions.