NCERT Activity 3.10 Class 10 Science Explanation

This activity has been taken from Chapter 3, Metals and Non-metals. In this activity, we will learn how metals react with water, with an explanation.

What Happens When Metal Reacts with Water?

Aim

 

To observe the reaction of different metals with water/ steam

Materials Required

    1. Samples of metals (Na, K, Ca, Mg, Zn, Fe & Cu)

    2. Beakers

    3.  Cold/ hot water and steam

    4. Test tubes

    5. Bunsen burner

    6. Delivery tube

    7. Tongs

Procedure

We collect the metals used in Activity 3.9. We place these metal pieces separately in beakers and add cold water. We observe what happens.

We note down which metals do not react with cold water, so we add hot water and observe.

Reaction of metals with water

Finally, we notice which metals remain unchanged when exposed to hot water; we then pass steam over them and observe what happens.

Observation 

Explanation

(i)  K, Na, and Ca react with cold water. K and Na produce fire on water. This is due to the heat energy produced in the reaction that burns the hydrogen evolved.

 2K+ H₂O →2KOH + H₂ + heat energy

  2Na + H₂O →2NaOH + H₂ + heat energy

(ii)  Ca and Mg start floating sometime. The H₂ produced in the reactions sticks with the metal in the form of bubbles, so these metals start floating.

Ca +  + 2H₂O →Ca(OH)₂ + H₂

Mg+  + 2H₂O →Mg(OH)₂ + H₂

(iii)   Al, Fe, and Zn react with steam and produce H₂. Cu did not react even with steam.

  2Al+ 3H₂O → Al₂O₃  + 3H₂

(iv) Order of reactivity of the given metals with water is:

  K > Na > Ca > Mg > AI > Zn > Fe > Cu

 

Conclusion

We can conclude that different metals have different reactivity with water. Some react with cold water, some with hot water, and some metals react with steam.

 Copper does not react.

 So, this activity shows the trends in the reactivity series.

Frequently Asked Questions

 

    1. Why do potassium and sodium catch fire when they react with water?

Answer – Because they produce a large amount of heat and hydrogen. Hydrogen is an inflammable gas, so it catches fire.

    2. Which metal does not react with water?

Answer – Copper does not react with water.

    3. Why do some metals float on water?

Answer – Metals like calcium form bubbles of hydrogen gas when they react with water, and these bubbles stick to the metal, so these metals float on water.

 Related Topics - 

1.  Activity 3.11

2. Activity 3.9

3. Solution of Chapter 3: Metals and Non-metals

4. MCQ Questions of Chapter 3

5. Extra Questions of Chapter 3

6. Solutions of Class 10 Science all chapters