Chemistry: Solubility of Liquids

Introduction

Some liquid substances dissolve in each other while others do not. When two miscible liquids are mixed, they form a homogeneous mixture. For example, ethanol and water mix in any proportion to form a single phase.

When two immiscible liquids are mixed, they form separate layers. For example, oil and water do not mix and form two distinct layers.

Procedure

1

Take 15cm³ of distilled water in one beaker and 15cm³ of ethanol in another beaker.

2

Pour water into ethanol.

3

A transparent solution will form, indicating that ethanol and water are miscible.

4

Take 10cm³ of oil in one beaker and 10cm³ of water in another beaker.

5

Pour water into oil. A cloudy mixture will form with two separate layers, indicating that oil and water are immiscible.

Observations

Water H2O
Ethanol C2H5OH
Oil

Water and Ethanol: Miscible (Form a homogeneous solution)

Water and Oil: Immiscible (Form separate layers)

Short Questions

1. What is the difference between miscible and immiscible substances?

Miscible substances have similar nature. For example, non-polar compounds dissolve in non-polar compounds. Substances with different natures do not mix, such as water and oil.

2. Why does ethanol dissolve in water?

Ethanol is a polar covalent compound, and water is also a polar covalent compound. Therefore, they mix with each other.

3. Why doesn’t sunflower oil dissolve in water?

Sunflower oil is a non-polar compound while water is a polar compound. Their natures are different, so sunflower oil does not dissolve in water.

Multiple Choice Questions

1. Which of the following pairs are miscible?

Water and olive oil
Mustard oil and olive oil
Water and chloroform
Water and sunflower oil

2. What is the chemical formula of ethanol?

CH3OH
C2H5OH
C3H7OH
C2H6O

3. Which principle explains why oil and water don’t mix?

Like dissolves like
Polar and non-polar substances don’t mix
Density differences
Surface tension

4. What happens when two immiscible liquids are mixed?

They form a homogeneous mixture
They form separate layers
They form a transparent solution
They form a colloidal solution

5. Which of the following is a polar solvent?

Water
Hexane
Benzene
Carbon tetrachloride

6. What type of compound is ethanol?

Polar covalent
Non-polar covalent
Ionic
Metallic

7. Which of these liquids would dissolve in water?

Acetic acid
Kerosene
Petroleum ether
Diesel

8. What is the main reason oil floats on water?

Oil is warmer than water
Oil is less dense than water
Oil is more viscous than water
Oil has higher surface tension

9. Which property makes a substance soluble in water?

High molecular weight
Polar nature
Non-polar nature
High boiling point

10. What would you observe when ethanol is mixed with water?

Formation of two layers
Formation of a clear solution
Formation of a cloudy mixture
Formation of bubbles