1. What is mole fraction?

The correct answer is: Ratio of moles of one component to total moles. Mole fraction is a way of expressing the concentration of a component in a mixture. It is calculated as:

χ_A = n_A / (n_A + n_B + ...)

2. Normality is defined as:

The correct answer is: Gram equivalents of solute per litre of solution. Normality (N) is a measure of concentration equivalent to molarity multiplied by the number of equivalents per mole of solute.

3. Which statements are correct?

Correct statements: Sum of all mole fractions in a solution equals 1, Mole fraction has no units, Normality = Molarity × n-factor. Normality does not depend on temperature directly, but the reaction conditions can affect it.

4. Calculate mole fraction of ethanol.

Given: 2 moles of ethanol and 8 moles of water.

χ_ethanol = n_ethanol / (n_ethanol + n_water) = 2 / (2 + 8) = 0.2

5. Find the normality of 0.5M H₂SO₄ solution.

Given: Molarity = 0.5M, n-factor for H₂SO₄ = 2 (since it can donate 2 protons).

Normality = Molarity × n-factor = 0.5 × 2 = 1 N

6. Calculate the mole fraction of each component.

Given: 23g of ethanol and 72g of water.

Moles of ethanol = 23 g / 46 g/mol = 0.5 moles

Moles of water = 72 g / 18 g/mol = 4 moles

χ_ethanol = 0.5 / (0.5 + 4) = 0.5 / 4.5 = 0.111

χ_water = 4 / 4.5 = 0.889

7. Volume of 0.2N HCl needed.

Using N₁V₁ = N₂V₂:

0.2N × V_HCl = 0.15N × 25 mL

V_HCl = (0.15 × 25) / 0.2 = 18.75 mL

8. Why is mole fraction useful in Raoult's Law?

Mole fraction is crucial in Raoult's Law as it helps in calculating the vapor pressure of each component in a solution. It provides a way to express the concentration of a component relative to the total amount of substance in the mixture.

9. When to use normality vs molarity?

Normality is used for reactions where equivalents are involved, such as acid-base and redox reactions. Molarity is used for general concentration measurements. Both concepts depend on the equivalent weight of the solute.

10. Design a simple experiment.

Example: Mix sugar and water to create a solution. Measure the amount of sugar and water used, then calculate the mole fraction of sugar in the solution. Discuss how this relates to the concept of mole fraction.