3. How does a physical change differ from a chemical change? Explain with examples.
4. 'Rusting of iron is a chemical change.' How can you establish this statement with the help
of an experiment?
5. How will you obtain pure crystals of copper sulphate?
6. Write the different ways in which rusting can be prevented.
7. What happens when an iron nail is placed in a copper sulphate solution? Explain.
8. When lemon juice is added to baking soda, a hissing sound is produced. Explain the
observation.
9. Explain why rusting of iron objects is faster in coastal areas than in deserts.
10. Explain whether magnetisation of an iron bar is a physical or chemical change. State reasons
for your answer.
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Answers
Answer:
3.Image result for How does a physical change differ from a chemical change? Explain with examples.
Some examples of physical change are freezing of water, melting of wax, boiling of water, etc. A few examples of chemical change are digestion of food, burning of coal, rusting, etc. Generally, physical changes do not involve the production of energy.
5.Pure copper sulphate can be obtained from an impure sample by re-crystallization. The impure sample is dissolved in water, heated and then cooled which then later forms crystals. These copper sulphate crystals are then separated by filtration and drying.
6.Galvanizing, Corten or Weathering Steel Stainless Steel, Regular maintenance.
7.Chemical reaction of iron nail with copper sulphate solution in water. Iron displaces copper ions from an aqueous solution of copper sulphate. ... In this reaction, metallic iron is converted into ferrous ion (Fe2+) and cupric ion (Cu2 +) is converted into metallic copper. Fe (s) + Cu2 + (aq) —→ Fe2+ (aq) + Cu (s).
8.When lemon juice is added to baking soda ,they both react . Carbon diocide is formed in the reaction . The hissing sound is produced by the evolution of the gas.
9.For rusting, the presence of air(oxygen) and moisture(water) is required. In coastal areas the quantity of moisture present in air is higher than in the deserts. Hence, rusting of iron objects is faster in coastal areas than in deserts.
10.Magnetization of iron is a physical change and not a chemical change as there is no change of state, no change of temperature, no smell and no evolution of gas. It is because: - No Chemical process is involved. - After demagnetizing the iron it will lose its magnetic power.
Answer:
3. Some examples of physical change are freezing of water, melting of wax, boiling of water, etc. A few examples of chemical change are digestion of food, burning of coal, rusting, etc. Generally, physical changes do not involve the production of energy.
4. Keep one iron metal in room, Then release oxygen, carbon dioxide etc..
5. Pure copper sulphate can be obtained from an impure sample by re-crystallization. The impure sample is dissolved in water, heated and then cooled which then later forms crystals. These copper sulphate crystals are then separated by filtration and drying.
6. The best ways to prevent rust include:
Galvanizing. Galvanizing is a method of rust prevention. ...
Corten or Weathering Steel. ...
Stainless Steel. ...
Proper Pre-Design. ...
Bluing. ...
7. Chemical reaction of iron nail with copper sulphate solution in water. Iron displaces copper ions from an aqueous solution of copper sulphate. ... In this reaction, metallic iron is converted into ferrous ion (Fe2+) and cupric ion (Cu2 +) is converted into metallic copper. Fe (s) + Cu2 + (aq) —→ Fe2+ (aq) + Cu (s).
8. When lemon juice is added to baking soda ,they both react . Carbon diocide is formed in the reaction . The hissing sound is produced by the evolution of the gas.
9. For rusting, the presence of air(oxygen) and moisture(water) is required. In coastal areas the quantity of moisture present in air is higher than in the deserts. Hence, rusting of iron objects is faster in coastal areas than in deserts.
10. Magnetization of iron is a physical change and not a chemical change as there is no change of state, no change of temperature, no smell and no evolution of gas. It is because: - No Chemical process is involved. - After demagnetizing the iron it will lose its magnetic power.
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