CBSE Chemistry Experiment Types of Reactions

Chemistry - Types of Reactions Experiment

One or more chemical compounds react to produce one or more products, the chemical reactions can be classified into: a) Combination reaction b) Decomposition reaction c) Displacement reaction d) Double Displacement reaction. The type of reaction is evident from the product of the chemical reaction.

Table of Content

• Aim

• Apparatus Required

• Reactions between water and quicklime

• Effect of heat on ferrous sulphate crystals

• The reaction between sodium sulphate and barium chloride solution

• Procedure

• Observations

• Results

Aim

To experimentally verify the types of reaction by performing and observing:

1. The reactions between water and quicklime.

2. The effect of heat on ferrous sulphate crystals.

3. The reaction between sodium sulphate and barium chloride solution.

Apparatus Required

• Test Tube

• Beaker

• Glass rod

• Measuring Cylinder

• Conical Flask

• Spatula

• Sandpaper

• Iron nails

• Test tube holder

• Test tube stand

• Bunsen burner

Test tube holder diagram

Theory

1. The reactions between water and quicklime

Calcium oxide is the chemical formula for quick lime (CaO). It reacts with water to produce calcium hydroxide [Ca(OH)2], also known as slaked lime.

 CaO + H2O→Ca(OH)2 + heat

1. A combination reaction occurs when two substances combine to form one product.

2. Because heat is produced during the reaction, it is referred to as an exothermic reaction.

3. The slaked lime solution is basic because it turns red litmus to blue.

4. Lime water is another name for freshly prepared slaked lime.

5. When carbon dioxide gas is passed through it, it turns milky.

2. Effect of heat on ferrous sulphate crystals

The colour of ferrous sulphate crystals is light green. The crystallisation of water causes the colour.

The following changes occur when ferrous sulphate crystals are heated.

2FeSO4.7H2O (s)→Fe2O3 (s) + SO2 (g) + SO3 (g)+14H2O

1. The colour changes to brown, and gases are released as new compounds form.

2. A decomposition reaction occurs when a single compound decomposes to form three new compounds.

3. SO2 and SO3 gas turn moist blue litmus paper red, indicating that it is acidic.

4. SO2 has the following reducing property: When SO2 gas passes through acidified potassium dichromate, it changes its orange colour to green.

5. The crystals release crystallisation water.

6. Because SO2 gas has a choking odour, avoid inhaling it and keep the test tube's mouth away from your face.

3. The reaction between sodium sulphate and barium chloride solution

1. Both sodium sulphate solution and barium chloride solution are colourless.

2. When the two solutions are mixed, a white precipitate is formed due to the formation of barium sulphate.

3. The reaction is known as a double displacement reaction because it involves the exchange of ions. 

4. As barium sulphate is insoluble in water, it precipitates. 

BaCl2 (aq) + Na2SO4 (aq)→BaSO4 (s) + 2NaCl (s)

Procedure

1. Reactions between water and quicklime

1. Take a clean beaker.

2. Add a small piece of lime to it.

3. Add water drop by drop into the beaker.

Reactions between water and quicklime

2. Effect of heat on ferrous sulphate crystals

a. Take a clean and dry test tube.

b. Add a few crystals of Ferrous Sulphate 

c. Fix it on a test tube holder.

d. Heat the test tube on the burner, keeping the mouth of the test tube away from your face.

e. Waft the gas released to smell and test it with wet litmus paper.

Effect of heat on ferrous sulphate crystals

3. The reaction between sodium sulphate and barium chloride solution

a. In a clean test tube, take sodium sulphate solution, to this add barium chloride solution.

b. Shake the contents and observe.

The reaction between sodium sulphate and barium chloride solution

Observations

Result

1. Reactions between water and quicklime

1. Quick lime and water combine to form one product Calcium hydroxide, which is slaked lime along with the evolution of heat (exothermic reaction). 

2. Hence, it's a combination reaction.

2. Effect of heat on ferrous sulphate crystals

1. Heating of ferrous sulphate crystals results in the decomposition of the compound into Fe2O3, SO2, and SO3. 

2. As the decomposition is brought about by heating, it is called a thermal decomposition reaction.  

3. The loss of water molecules from the ferrous sulphate crystals changes the colour from green to white.

3. The reaction between sodium sulphate and barium chloride solution

1. A white precipitate of barium sulphate is formed upon mixing barium chloride and sodium sulphate, due to a double displacement reaction.

Precautions

1. Do not touch quicklime with your hands, use tongs.

2. Mixing quicklime and water releases a large amount of heat, so add water drop by drop and use a borosil beaker.

3. For heating, use hard glass tubes.

4. Never inhale any gas, just waft the gas.

5. Do not touch any chemicals with your hands.

6. Keep the mouth of the test tube away from your face while heating.

Lab Manual Questions

1. What is Quicklime?

Ans:  Quick Lime is chemically known as Calcium Oxide (CaO)

2. What is the formula of ferrous sulphate crystals?

Ans: Chemical formula of ferrous sulphate - FeSO4.7H2O

3. What is the metal deposited on the iron nails when dipped in copper sulphate solution?

Ans: Copper metal deposits on the iron nails

4. What is the white precipitate formed when sodium sulphate and barium chloride are mixed?

Ans: Barium sulphate forms the white precipitate.

Viva Questions

1. How can you prepare lime water?

Ans: Mix calcium oxide and water

2. What is the product of mixing calcium oxide in water?

Ans: Calcium Hydroxide Ca(OH)2

3. What is a combination reaction?

Ans: The reaction where two compounds combine to give one product.

4. What are the products of the decomposition of ferrous sulphate?

Ans: On heating, ferrous sulphate crystals decompose into Ferric oxide (Fe2O3), Sulphur dioxide (SO2), and Sulphur trioxide (SO3)

5. What gases evolved during the decomposition of ferrous sulphate?

Ans: Sulphur dioxide (SO2) and Sulphur trioxide (SO3)

6. Name the reaction: heating of ferrous sulphate crystals?

Ans: Thermal decomposition reaction

7. What is the basic principle of the experiment of iron nails dipped in copper sulphate?

Ans: In this experiment, the highly reactive metal (Fe) displaces the lower reactive copper from copper sulphate to form ferrous sulphate.

8. Define double displacement reaction.

Ans: A reaction where two ionic compounds exchange their ions to form new insoluble compounds.

Practical Based Questions

1. Which of the following reactions does occur, as shown

1. Zn(s)  +  ZnSO4(aq) → 

2. Fe(s)  +  ZnSO4 (aq) →

3. Cu(s)  +  ZnSO4 (aq) →

4. 2Al(s)  +  3ZnSO4(aq) →

Ans: The only reaction that occurs is 2Al(s)  +  3ZnSO4(aq) → Al2(SO4)3  + 3Zn (s). As Aluminium is more reactive than zinc.

2. Identify the combination reactions in the following

1. NH3+HCl→NH4Cl

2. NaOH+KOH→NaOH+KCl

3. 2CO+O2→2CO2

4. BaCl2+Na2SO4→BaSO4+2NaCl 

Ans: The formation of ammonium chloride and carbon dioxide is a combination reaction.

3. What is Ferrous Sulphate?

1. Blue vitriol

2. Quick Lime

3. Green vitriol

4. Slaked Lime

Ans: Ferrous sulphate is known as green vitriol.

4. What is the colour of the deposition on iron nails?

1. Blue 

2. Brown 

3. Green 

4. White

Ans: The deposition on the iron nail is brown.

5. What is the colour of the copper sulphate solution?

1. Blue 

2. Brown 

3. Green 

4. White

Ans: Copper sulphate crystals are blue.

6. The reaction between Barium chloride and sodium sulphate is 

1. Combination reaction

2. Double displacement reaction

3. Displacement reaction

4. Decomposition reaction

Ans: Double Displacement reaction

7. The white precipitate in the sodium sulphate and barium chloride reaction formed is

1. CaO

2. Ca(OH)2

3. Fe2O3

4. BaSO4

Ans: Sodium sulphate and Barium Chloride react to form a white precipitate of barium sulphate

8. Identify the combination reaction in the following equation

1. 2C8H18+25O2→16CO2+18H2O

2. 8Fe+S8→8FeS

3. MgO+CO2→MgCO3

4. 3Pb(NO3)2+2AlCl3→3PbCl2+2Al(NO3)3

Ans. In a combination reaction, two or more reactants combine to form a single product. Only in the following reactions, two reactants combine to form one product.

8Fe+S8→8FeS

MgO+CO2→MgCO3

9. How many water molecules do ferrous sulphate crystals contain?

1. 1

2. 3

3. 5

4. 7

Ans: Ferrous sulphate crystals contain seven water of crystallisation.

Conclusion

The experiments demonstrated the different types of reactions:

1. The reactions between water and quicklime, demonstrated the combination reaction, as CaO and H2O combined to form calcium hydroxide 

2. Ferrous sulphate crystals were heated to demonstrate the decomposition reaction, where FeSO4 decomposed into multiple compounds.

3. The effect on iron nails dipped in copper sulphate solution displayed colour change due to displacement reaction with iron displacing the copper from copper sulphate forming ferrous sulphate.

4. The reaction between sodium sulphate and barium chloride solution is an example of a double displacement reaction where ions are exchanged to form new compounds.