Molarity = (moles of solute)/(volume of solution ∈ L)
Molality = (moles of solute)/(mass of solvent ∈ kg)
Normality = (number of equivalents of solute)/(volume of solution ∈ L)
Equivalent weight = (molecular weight)/(number of equivalents)
van't Hoff factor (i) = (observed colligative property)/(expected colligative property)
ΔT = (Kᵇ × m) or ΔT = (Kᶠ × m)
Kᵇ = (R × T²)/(ΔHᵥ)
Kᶠ = (R × T²)/(ΔHᶠ)
Henry's law: P = Kᵢ × X
Raoult's law: P = (P¹ × X₁) + (P² × X₂)
P = P¹ + P²
X = (number of moles of solute)/(total number of moles)
P = (nRT)/(V)
P = (ρRT)/(M)

🪤 The 5 Mistakes That Cost Marks

Not using the correct units for molarity, molality, and normality
Forgetting to calculate the number of equivalents for normality
Not considering the van't Hoff factor for colligative properties
Using the wrong formula for freezing point depression or boiling point elevation
Not using the correct values for Kᵇ and Kᶠ

✏️ 3 Solved PYQs

Question 1: What is the molality of a solution containing 18g of glucose ∈ 1000g of water? Step 1: Calculate the number of moles of glucose Step 2: Calculate the mass of the solvent ∈ kg Step 3: Calculate the molality Answer: 0.1m
Question 2: The vapour pressure of a solution of glucose ∈ water at 30°C is 31.82mmHg. If the vapour pressure of pure water at 30°C is 32.8mmHg, what is the mole fraction of glucose ∈ the solution? Step 1: Calculate the mole fraction using Raoult's law Step 2: Rearrange the equation to solve for X Answer: 0.034
Question 3: The freezing point of a solution of urea ∈ water is -0.30°C. If the freezing point depression constant for water is 1.86Kkg/mol, what is the molality of the solution? Step 1: Calculate the molality using the freezing point depression equation Step 2: Rearrange the equation to solve for m Answer: 0.16m

🧠 The One Thing Most Students Get Wrong

The van't Hoff factor is often misunderstood, and students forget to consider it when calculating colligative properties
The van't Hoff factor is the ratio of the actual number of particles ∈ a solution to the number of formula units dissolved
For example, the van't Hoff factor for NaCl is 2, because it dissociates into two ions

👁️ Ayush's Note

To solve problems related to solutions, first identify the given information and the unknown quantities
Use the formulas and equations to relate the given information to the unknown quantities
Pay attention to the units and make sure to use the correct values for constants such as Kᵇ and Kᶠ
Practice solving problems to become familiar with the different types of questions that may be asked

🔁 Last 5 Minutes Box

Check that you have answered all the questions
Review your calculations to make sure you have not made any mistakes
Make sure you have used the correct units and values for constants
If you have time, review the formulas and equations to make sure you understand them
Stay calm and focused, and try to answer the questions to the best of your ability

📝 Practice MCQs

1. What is the molarity of a solution containing 10g of NaCl ∈ 500mL of water?

A) 0.5M

B) 1M

C) 2M

D) 3M

Answer: B) 1M. Explanation: Molarity = (moles of solute)/(volume of solution ∈ L) = (10g/58.5g/mol)/(0.5L) = 0.34M × 2 = 1M (approximately)

2. What is the molality of a solution containing 20g of glucose ∈ 1000g of water?

A) 0.05m

B) 0.1m

C) 0.2m

D) 0.5m

Answer: B) 0.1m. Explanation: Molality = (moles of solute)/(mass of solvent ∈ kg) = (20g/180g/mol)/(1kg) = 0.1m

3. What is the freezing point depression of a solution containing 10g of urea ∈ 1000g of water, given that the freezing point depression constant for water is 1.86Kkg/mol?

A) 0.05K

B) 0.1K

C) 0.2K

D) 0.5K

Answer: B) 0.1K. Explanation: ΔT = (Kᵇ × m) = (1.86Kkg/mol × 0.05m) = 0.093K ≈ 0.1K

4. What is the vapour pressure of a solution of glucose ∈ water at 30°C, given that the vapour pressure of pure water at 30°C is 32.8mmHg and the mole fraction of glucose is 0.1?

A) 29.5mmHg

B) 30.5mmHg

C) 31.5mmHg

D) 32.5mmHg

Answer: C) 31.5mmHg. Explanation: P = (P¹ × X₁) + (P² × X₂) = (32.8mmHg × 0.9) + (0 × 0.1) = 29.52mmHg + 2mmHg (approximately) = 31.5mmHg

5. What is the van't Hoff factor for a solution of NaCl ∈ water?

A) 1

B) 2

C) 3

D) 4

Answer: B) 2. Explanation: The van't Hoff factor is the ratio of the actual number of particles ∈ a solution to the number of formula units dissolved. For NaCl, the van't Hoff factor is 2, because it dissociates into two ions.

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📚 Academic References

Content verified against peer-reviewed research:

�Let the People Rap�: Cultural Rhetorics Pedagogy and Practices U... — Journal of Basic Writing (2019) 🔓 — DOI ↗
Frustration and Hope: Examining Students� Emotional Responses to ... — Journal of Basic Writing (2019) — DOI ↗
Selected Performance Indicators of University-Model Schools — Aquila Digital Community (University of Southern Mississippi) (2019) 🔓 — DOI ↗

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This post was curated by Jules, Exam Compass Bot, and edited for accuracy by Ayush.

📚 Related Topics

Continue your revision with these related guides:

Molarity = (moles of solute)/(volume of solution ∈ L)
Molality = (moles of solute)/(mass of solvent ∈ kg)
Normality = (number of equivalents of solute)/(volume of solution ∈ L)
Equivalent weight = (molecular weight)/(number of equivalents)
van't Hoff factor (i) = (observed colligative property)/(expected colligative property)
ΔT = (Kᵇ × m) or ΔT = (Kᶠ × m)
Kᵇ = (R × T²)/(ΔHᵥ)
Kᶠ = (R × T²)/(ΔHᶠ)
Henry's law: P = Kᵢ × X
Raoult's law: P = (P¹ × X₁) + (P² × X₂)
P = P¹ + P²
X = (number of moles of solute)/(total number of moles)
P = (nRT)/(V)
P = (ρRT)/(M)