CBSE Chemistry Experiment Mixture and Compound

Introduction

A mixture is a substance made up of two or more elements that can be physically separated from one another. There are many types of mixtures everywhere around you, including air in the environment, a solution of water and salt, sugar and water, and various gases. 

When two or more chemical elements are brought together, a compound is formed. There are numerous examples of compounds that are used frequently, such as sodium chloride, and calcium chloride.

Table of Content 

• Aim

• Physical changes

• Chemical changes

• Mixtures

• Compounds

• Result

Aim

To prepare a mixture and a compound by combining iron filings and sulphur powder and to distinguish between the mixture and the compound based on their appearance, behaviour towards magnet and carbon disulphide.

Materials Required

• Bunsen burner

• Tripod Stand

• Wire gauze

• Test tube stand

• Test tubes

• Test tube holder

• China dish

• Watch glass

• Magnet

• Iron filings

• Carbon disulphide

• Sulphur powder

Theory

• Physical Changes

A substance's chemical content is unaffected by physical changes; only its appearance is altered. A procedure that doesn't transform a substance into something else entirely. The freezing of water, melting of wax, boiling of water, etc. are some examples of physical change.

• Chemical Changes

A substance undergoes chemical transformations, becoming a completely new substance with a new chemical formula. Chemical reactions are another name for chemical transformations which is a procedure that involves changing one material (or several substances) into another and creating or breaking interatomic connections.

• Mixtures

A mixture is defined as a substance made up of two or more substances that are physically separable. 

• Compounds

A compound is a material that is produced when two or more chemical elements are joined. One of the many instances of a substance that is often used is sodium chloride.

The compound formation is a chemical change as opposed to mixture creation, which is a physical change. In this experiment, mixtures and compounds will behave differently to magnet and carbon disulphide.

Procedure

1. Preparing a mixture of iron filings and sulphur powder

• First, we properly mixed some amount of sulphur powder with iron filings.

• Thus, a Mixture of sulphur powder and iron filings was the result.

• Then we keep the Mixture formed in a china dish.

• Bring a magnet to a mixture of iron filings and sulphur powder in a China dish.

• After that, pour the mixture from the china dish into a test tube containing carbon disulphide.

Mixture Preparation

2. Making a compound out of iron filings and sulphur powder

• First, we placed a small amount of iron filings and sulphur powder in a test tube.

• The mixture was then heated over a flame.

• The iron sulphide compound was formed as a result of a reaction between iron and sulphur on heating. 

• The compound is to be kept on a china dish.

• Bring a magnet to the compound in the china dish and observe what happens.

• Then pour the compound into a test tube containing carbon disulphide and note down the observation. 

Compound Preparation

Observation

Result

1. Mixtures are prepared by mixing iron filings and sulphur powder, which is heterogeneous, can be separated by magnetic separation and does not behave towards carbon disulphide.

2. Compounds are formed by heating iron filings and sulphur powder which are homogeneous, can not be separated by the magnet and react with carbon sulphide.

Precautions

• In a china dish or a hard glass, warm the mixture of iron filings and sulphur powder.

• Don't breathe in any of the experiment's emitted gas.

• Avoid exposing carbon disulphide to flame.

Lab manual questions

1. How can mixtures be separated?

Ans: Depending on the characteristics of the constituents, mixtures can be separated using a variety of physical techniques, such as filtering, decantation, evaporation, and magnetic separation.

2. Why can a mixture of sulphur and iron be separated using a magnet?

Ans: Iron, which is magnetic and retains its qualities in a mixture, is drawn to the magnet and can be separated from sulphur, which is not, by doing so.

3. Is mixing iron and sulphur a physical or chemical change?

Ans: It's a chemical change because both lose their properties.

4. What are different separating methods?

Ans: 

• Hand-picking.

• Threshing.

• Winnowing.

• Sieving.

• Evaporation.

• Distillation.

• Filtration or Sedimentation.

• Separating funnel.

Viva questions

1. What are the different types of mixtures?

Ans: Mixtures are of two types based on their composition, Homogeneous and heterogeneous.

2. Give a few examples of mixtures.

Ans: Soda water, seawater and soil, air.

3. What is meant by physical change?

Ans: Physical changes are mainly reversible changes. No new product is formed in the physical changes.

4. Is rusting of iron a chemical change?

Ans: On rusting iron is converted into iron oxide. As a new product is formed it is a chemical change.

5. What is meant by compounds?

Ans: Compounds are substances made up of combining different elements in a particular ratio.

6. Is salt water a compound or a mixture?

Ans: Salt water is a homogeneous mixture where salt and water are in definite proportion.

7. Can magnetic separation apply to all mixtures?

Ans: No, only mixtures with magnetic properties, mainly metal, can be separated by magnetic separation.

8. Is water a mixture or a compound?

Ans: Because it is composed of molecules of hydrogen and oxygen, water is a compound. Water atoms don't exist. The ratio of two hydrogen atoms to one oxygen atom determines the composition of water molecules.

9. What are the different types of compounds?

Ans: Molecular, ionic and intermetallic, coordinate compound.

10. Give examples of a few compounds.

Ans:  Table salt, carbon dioxide and cellulose, baking soda are examples of compounds.

Practical-based questions

1. What is the separation method for the iron and sulphur mixture?

1. Filtration

2. Magnetic separation

3. Decantation

4. Evaporation

Ans: (a) Magnetic separation. It is used to separate the mixture, iron powder will stick to the magnet.

2. What type of change occurs during the formation of compounds?

1. Physical change

2. Chemical change

3. No change

4. Both a & b

Ans: (B) Chemical Change. During the formation of a compound a new substance is formed, hence it is a chemical change.

3. Physical changes are generally _____.

1. Reversible

2. Irreversible

3. Both A) and B)

4. None of the above

Ans: (A) Reversible. A physical change is when a substance experiences a change in its physical characteristics. A physical change can usually be reversed.

4. Choose the compound from the following:

1. Crude oil

2. Seawater

3. Water

4. Ink

Ans: (C) Water. Water is a compound where ink, seawater, and crude oil are mixtures.

5. What are the methods to separate constituents from compounds?

1. Hand-picking

2. Filtration

3. Electrochemical method

4. Evaporation

Ans: (C) Electrochemical method. There are only two ways to separate a compound's constituents: chemically or electrochemically.

6. Which separation method is used for mixtures?

1. Evaporation

2. Filtration

3. Decantation

4. All of the above

Ans: (D) All of the above. Evaporation, filtration and decantation are common separation methods for mixtures.

7. Identify homogeneous mixtures.

1. Air

2. Oil in water

3. Vinegar

4. Both A) and C) 

Ans: (D) Both (A) and (C). Air and vinegar are homogeneous mixtures having the same proportion of components.

8. Calcium chloride is an _____ compound.

1. Ionic

2. Molecular

3. Coordinate

4. Intermetallic

Ans: (A) Ionic. Calcium and chloride form an ionic bond, hence it is an ionic compound.

9. Choose the correct statement for heterogeneous mixtures.

1. They have the same composition

2. They have different compositions

3. Vinegar is a heterogeneous mixture

4. Both A) and C) 

Ans: Heterogeneous mixtures have different compositions.

10. What are examples of chemical change?

1. Stretching of rubber

2. Cooking

3. Burning

4. Both C) and D)

Ans: Cooking and burning are chemical changes where new substances are formed.

Conclusion 

From the preparation of the compound and mixture, we concluded that mixtures are heterogeneous and compounds are homogeneous substances. Mixture constituents particles can be separated physically by a magnet, while compounds can be separated only through chemical separation. Both compound and mixture react differently towards chemicals like carbon sulphide. Mixtures undergo physical changes, whereas compounds undergo chemical changes.