Activity 3.9 NCERT Class 10 Science, Metals and Non-metals

Activity 3.9 NCERT Class 10 Science, Chapter 3 Metals and Non-metals

Brief procedure:

Activity 3.9 asks us to burn various metals and observe their flame.

Observation: 

Not all metals burn easily, Copper and aluminium take time to burn.

Flame colour:

Sodium: Yellow

Magnesium: White

Aluminium: Silver white

Copper :blue flame

Solubility:

Highly reactive metals like sodium and potassium reacts with water and form soluble hydroxide. But most other metals are not so reactive. So they are not soluble in water.

Only some metal oxides that from metal hydroxide with water, are soluble in water. Else they are insoluble. Beryllium and magnesium are exceptions as they are slightly soluble in water.

Metal oxide + H₂O(l) ———> Metal Hydroxide.

Explanation:

Metals are highly reactive elements. They react with oxygen readily to form metal oxides. Highly reactive metals like lithium, sodium, potassium, beryllium, magnesium react spontaneously. Other metals like Aluminum, copper take time to burn. It produces a specific flame colour. Many times flame colour is used to find the constituent of the substance.

Metal + O₂(g) ———> Metal oxide(s)

Inference/conclusion: 

Metals on the heating burn to produce its oxides. During this process, they produce characteristic flames.

Next: See how various metals react with water. Activity 3.10.

See also: The reaction of oxides of metal and non-metal with water, Activity 3.8.

 

Ref: Flame test Wikipedia.