The activity has been taken from the chapter Acids, Base and Salts Class 10 Science.
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What happens when acid or base is mixed with water
Aim of the activity
To observe the reaction between acid and water and identify whether the reaction is exothermic or endothermic.
Materials used in the activity
1. 10 ml distilled water
2. Concentrated H2SO4
3. Sodium hydroxide pellets
4. Dropper
5. Glass rod
6. 100mL beaker
7. Gloves and goggles
Procedure
(i) With sulphuric acid
We take 10 mL distilled water in a beaker and add concentrated sulphuric acid with dropper gently and carefully. After adding the acid, we will touch the outer surface of beaker to note the change in temperature.
(ii) With sodium hydroxide
We take 10 mL distilled water in a beaker and add a few sodium hydroxide pellets in it and swirl the solution gently and carefully with a glass rod. After adding the acid, we will touch the outer surface of beaker to note the change in temperature.
Observation
(i) The outer surface of beaker becomes hot after adding H2SO4.
(ii) The outer surface of beaker becomes hot after adding sodium hydroxide pellets.
Explanation
Heat is released when sulphuric acid and sodium hydroxide are added to water.
When H2SO4 is added to water, it ionizes and release a large amount of heat.
When sodium hydroxide dissolves in water, it releases energy so temperature increases.
Conclusion
This activity indicates that the reaction is exothermic when acid or base is added to water, because heat is produced
Precautions
1. Always wear gloves and goggles during this activity.
2. Always add acid to water.
Frequently Asked Questions
1. Why does the beaker become hot when acid or base is added to water?
Answer – Because They release heat when they are dissolve in water.
2. What is an exothermic reaction?
Answer – The chemical reaction in which heat is released is called exothermic reaction.
3. Is it safe to mix water to acid?
Answer – No, water is not mixed into acid because the reaction is exothermic and acid may be splashed with water vapour.
4. What kind of changes occur the reaction – Physical or chemical?
Answer – This change is a physical change.
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