CBSE Chemistry Experiment Types of Reaction and Changes

Introduction to Types of Reactions and Changes

Chemical reactions operate under the principle of type of reactions and changes that if a reactive substance interacts with other chemicals, different reactions will occur. Chemical reactions also occur in stable or least reactive compounds, although under more extreme circumstances. In a chemical reaction, heat is released or absorbed, bubbles, gas, and fumes are formed, and the reactants' colours change when they combine to produce a product and it leads to chemical change. The inter-conversion of condition occurs during physical change. There are for different types of chemical reactions namely, combination, decomposition, displacement, and double displacement reactions and while undergoing this reaction there occurs certain changes. The types of reactions and changes experiment procedure, observation, and its results are explained below.

Table of Content

• Aim

• Procedure for reaction of iron nails with aqueous copper sulphate solution

• Procedure for reaction of barium chloride and sodium sulphate aqueous solutions

• Procedure for reaction of zinc and dilute sulphuric acid

• Procedure for reaction of magnesium ribbon combustion in oxygen

• Procedure for reaction of heating of ferrous sulphate 

• Result

Aim

To perform the chemical reactions listed below and categorize them as physical and chemical changes:-

• Iron nails with aqueous copper sulphate solution

• Barium chloride and sodium sulphate aqueous solutions

• Zinc and dilute sulphuric acid

• Magnesium ribbon combustion in oxygen

• Heating of ferrous sulphate

Apparatus Required

Iron nails, freshly prepared aqueous CuS04 solution, zinc granules, dil. H2S04 , magnesium Ribbon, Ferrous sulphate crystals, sodium sulphate and barium chloride aqueous solutions, watch glass, pH paper strips, test tube, test tube holders, boiling tube,  capillary tube fixed with cork, clamp stand, ,thread, burner, and tongs. 

Theory

Chemical Reactions

Combination reaction occurs when a single product is created when two substances or elements come together. The combination reaction is explained below with an example of magnesium ribbon combustion with air.

\[2Mg + {O_2} \to 2MgO\] 

Decomposition reaction occurs when a molecule breaks down into a simpler molecule as a result of heat, light, electricity, or energy. The decomposition reaction is explained below with an example of heating of copper sulphate.

\[CuS{O_4}.5{H_2}O \to CuS{O_4} + 5{H_2}O\] 

Displacement reaction happens whenever a highly reactive metal combines with a lesser reactive metal's salt, it replaces the lesser reactive metal and creates a different compound. The displacement reaction is explained below with the example of iron and copper sulphate solution.

\[Fe + CuS{O_4} \to FeS{O_4} + Cu\] 

Double displacement reaction happens whenever two salts are combined in solution state in this chemical reaction, ions begin to exchange, and a fresh compound is created. The double displacement reaction is explained below with the example of sodium sulphate and barium chloride solutions.

\[N{a_2}S{O_4} + BaC{l_2} \to BaS{O_4} + 2NaCl\] 

Changes

Physical change is defined as a change in a substance's properties that does not affect its chemical composition or constitution. Chemical change is a change that changes the chemical composition of matter and produces a different substance.

Procedure

Procedure for Reaction of Iron Nails with Aqueous Copper Sulphate Solution

• Using distilled water, rinse and dry 2 test tubes.

• Label as A and B on the test tube.

• In the A test tube, take solid copper sulphate and dissolve it with 20mL of distilled water. Then to B test tube transfer 10mL of aqueous copper sulphate solution.

• Evaluate the intensity of aqueous CuSO4 solutions blue colour in both the test tube

• Using sandpaper, clean the two iron nails and dip 1 iron nail to test tube A and other one to B test tube for 15 minutes. Then record the observations.

Procedure for Reaction of Barium Chloride and Sodium Sulphate Aqueous Solutions

• Using distilled water, rinse and dry 2 test tubes.

• Label as A and B on the test tube.

• In test tube A, pour 5mL barium chloride solution and in test tube B pour 5mL of sodium sulphate solution and observe the colour of solutions in both test tubes.

• Then transfer both solutions into a conical flask and mix the solution using a glass rod.

• The mixture of solutions should be undisturbed for a while and observe the colour change and record the observation.

Procedure for Reaction of Zinc and dilute Sulphuric Acid

• In a clean and dry boiling tube take zinc granules and add dilute sulphuric acid to it.

• The glass capillary tube attached to the boiling tube by a cork should be immediately closed. 

• Take the blazing flame very close to the capillary tube's mouth.

• Observe the change and record the observation.

Procedure for Reaction of Magnesium Ribbon Combustion in Oxygen

• Clean the magnesium ribbon using the sandpaper.

• Then introduce the magnesium ribbon to the flame with the aid of tongs.

• Gather the combusted white powder in a watch galls and pour a few drops of distilled water to it.

• Then check the pH of the paste using a red litmus pH strip. 

• Observe the change and record the observation.

Procedure for Reaction of Heating of Ferrous Sulphate

• Using distilled water clean and the boiling tube.

• In the dry boiling tube take 2g of solid ferrous sulphate and note the colour of it.

• Heat the boiling tube contained sample using a test tube holder in a Bunsen burner.

• Observe the residue's colour and smell the gas emissions' odour. In close proximity to the boiling tube's mouth, place the red and blue litmus paper strips.

• Observe and record the change.

Observations

Result

The results of the types of reaction and changes experiments implies that

• Iron nails with aqueous copper sulphate solution are a displacement reaction with chemical change.

• A barium chloride and sodium sulphate aqueous solution is a double displacement reaction with chemical change.

• Zinc and dilute sulphuric acid is a displacement reaction with chemical change.

• Magnesium ribbon combustion in oxygen is a combination reaction with chemical change.

• Heating of ferrous sulphate is a decomposition reaction with chemical change.

Precautions

• Handle chemicals and apparatus with caution.

• Every apparatus should be rinsed with distilled water, and dried before starting the experiment.

• While heating or boiling, utilize a test tube holder.

• Prepare solutions using only distilled water.

• Throughout the stability testing, don't tamper with the mixture.

• Using a dropper, dispense a small amount of the mixture onto the red and blue litmus strips.

• After the completion of the experiment, wash your hands thoroughly.

Lab Manual Questions

1. Why only good quality apparatus are used for heating or boiling solutions?

Ans: During the heating or boiling experiment, utilize a glass beaker of high quality since a poor-quality beaker runs the risk of cracking because of the exothermic process.

2. Why Iron nails with diluted aqueous copper sulphate solution?

Ans: In this chemistry experiment dilute copper sulphate solution is used instead of concentrated copper solution because colour change will not be visible if concentrated solution is used.

3. Why is dilute acid added during the preparation of the colloidal solution?

Ans: Magnesium ribbon should indeed be cleaned prior to burning in order to eliminate the oxide layer that has been developed over it, as it makes the ribbon passive and easy to ignite.

4. Why dark-coloured goggles advised for viewing the magnesium ribbon combustion in oxygen?

Ans: White dazzling flame is produced when magnesium ribbon is burned; to safeguard our eyes, dark-coloured goggles are worn during the experiment.

Viva Questions

1. What kind of reaction occurs between quicklime and water?

Ans: Combination reaction.

2. What is the other name of quicklime?

Ans: CaO-calcium oxide.

3. What is the other term of decomposition reaction?

Ans: Thermal decomposition reaction

4. Is it possible for magnesium to react with oxygen and produce substances other than MgO?

Ans: Yes. Magnesium can also generate magnesium nitride (Mg3N2) by reacting with nitrogen which exists in air.

5. What is the other name of solid ferrous sulphate?

Ans: Green vitriol.

6. What is the other term of combination reaction during magnesium ribbon combustion with oxygen?

Ans: Exothermic reaction.

7. Given one example of chemical change.

Ans: Burning of fuel or oil

8. Give one example of physical change.

Ans: Melting of wax.

9. Why does copper sulphate crystals colour change on heating?

Ans: Due to loss of water from crystallization.

10. Mention one of the decomposition reactions which take place in the human body?

Ans: Decomposition of protein.

Practical-Based Questions

1.  Identify the two gases that emerged during the decomposition reaction?

1. Carbon dioxide and sulphur dioxide

2. Sulphur dioxide and hydrogen gas

3. Sulphur dioxide and sulphur trioxide

4. Sulphur dioxide and nitrogen gas

Ans: Sulphur dioxide and sulphur trioxide are the two gases evolved during decomposition reaction.

2. What is the decomposition reaction's residue colour?

1. Green

2. Red

3. Blue

4. Brown

Ans: The colour of decomposition reactions residue is brown.

3. What type of reaction occurs while heating copper sulphate?

1. Combination

2. Decomposition

3. Displacement

4. Double displacement

Ans: Heating copper sulphate leads to decomposition reaction.

4. What colour is observed after rubbing magnesium ribbon with sand paper?

1. Brown

2. Black

3. Grey

4. Silvery white

Ans: Magnesium ribbon exhibits silvery white colour.

5. At what temperature does copper sulphate decompose during heating of copper sulphate?

1. 150oC

2. 250oC

3. 350oC

4. 45OoC

Ans: Copper sulphate decomposes entire water molecules at 250oC.

6. What is the colour of copper sulphate with water molecules and anhydrous compound?

1. Red and blue

2. Red and brown

3. Blue and red

4. Blue and dirty white

Ans: The colour of copper sulphate with water molecules and anhydrous compound are blue and dirty white.

7. What gas evolved during heating zinc sulphate?

1. Nitrogen. 

2. Oxygen.

3. Hydrogen.

4. Carbon dioxide. 

Ans: Hydrogen gas is evolved during heating of zinc sulphate. 

8. What type of compounds are barium chloride and sodium sulphate?

1. Covalent

2. Ionic

3. Ionic and covalent

4. Covalent and ionic

Ans: Barium chloride and sodium sulphate are ionic compounds.

9. What is the colour of ZnSO4 produced during the displacement reaction?

1. Colourless

2. white

3. black

4. brown

Ans: It produces a colourless ZnSO4.

10. What happens while adding zinc granules to a dilute sulphuric acid?

1. Zinc metal changes the colour from grey to white

2. The zinc metal's surface gets brighter

3. Zinc granules becomes powder

4. The zinc granules' size continues to diminish

Ans: The zinc granules' size continues to diminish after adding it to a dilute sulphuric acid.

Conclusion

The types of reactions and changes experiment infer that Fe2O3, SO2, and SO3 are produced during the decomposition reaction that takes place when ferrous sulphate crystals are heated. When iron nails were immersed in a copper sulphate solution for 15 min, the solution's colour changed to green and brown red copper metal was coated upon the iron nails through displacement reaction. When sodium sulphate and barium chloride solutions are combined, a twofold decomposition reaction occurs, producing a white precipitate product by switching their ions. The magnesium ribbon while burning in presence of air combines with oxygen through combination reaction and produces magnesium oxide.