Activity 1.5 Class10 Science

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Aim of the activity

To observe the effect of heat on ferrous sulphate crystals and identify the changes in the colour due to the chemical reaction.

Activity 1.5 Class 10 Science diagram

Material used in the activity

  1. Boiling tube
  2. Ferrous sulphate crystals
  3. Tongues
  4. Spirit lamp or burner

Procedure

We will take about 2 g Ferrous sulphate crystals in a dry boiling tube and heat over the flame of  a burner or spirit lamp.

Observation

We observe the initial colour of ferrous crystals is light green but after heating  ferrous sulphate crystals lose their green colour and turn white accompanied by pungent smell.

Explanation

Ferrous sulphate crystals are hydrated salts containing water of crystallization which is responsible for green colour of crystals.

When ferrous sulphate crystals are heated, they lose water of crystallization and become anhydrous ferrous sulphate which is white in colour

On further heating of anhydrous ferrous sulphate produces ferric oxide, Sulphur dioxide and Sulphur trioxide.

FeSO4.7H2O(s)      →    FeSO4(s)               +           7H2O(g)

Ferrous sulphate     Anhydrous ferrous sulphate         Water

         

2FeSO4(s)       →   Fe2O3(s)  +     SO2(g)            +        SO3(g)

Ferrous sulphate     Ferric oxide   Sulphur dioxide        Sulphur trioxide  

 

Conclusion

The activity shows the loss of water of crystallization and decomposition reaction of ferrous sulphate that produces ferric oxide (dark brown), `SO_2` and `SO_3` gases with pungent smell.

Precaution: Do not point the mouth of boiling tube at your neighbours or yourself.

FAQs

  1. Why do the ferrous sulphate crystals change colour when heated?

Ans – The colour of ferrous sulphate crystals change due to loss of water of crystallization when heated.

  1. What gases are released during the heating of ferrous sulphate crystals?

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

  1. What is the initial colour of ferrous sulphate crystals?

Ans – Ferrous sulphate (FeSO4.7H2O)

  1. What is the colour of anhydrous ferrous sulphate?

Ans –  White or off white

  1. What is the final product of this activity?

Ans – Ferric oxide along with SO2 and SO3 gases

Related Topics

Topics
Activity 1.1
Activity 1.2
Activity 1.3
Activity 1.4
Activity 1.5
Activity 1.6
Activity 1.7
Activity 1.8
Activity 1.9
Activity 1.10
Activity 1.11

 

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