Solve this:
Q.4. Why bubbles are formed on the sides of vessel and at the bottom of the water when water starts boiling?
The bubbles form because of two reasons:
1. Because of already dissolved gases in water. As water is heated, because of agitation these dissolved gaseous molecules rise up and escape.
2. Because of non-uniform heating. If we heat water using a utensil which supplies heat only from bottom, the water attains an upward-decreasing temperature profile. Which means the water at the bottom is at a higher temperature. This leads 'water at the bottom' to reach boiling point faster than the rest of the water and hence it evaporates early and we can see bubbles in the bottom.
1. Because of already dissolved gases in water. As water is heated, because of agitation these dissolved gaseous molecules rise up and escape.
2. Because of non-uniform heating. If we heat water using a utensil which supplies heat only from bottom, the water attains an upward-decreasing temperature profile. Which means the water at the bottom is at a higher temperature. This leads 'water at the bottom' to reach boiling point faster than the rest of the water and hence it evaporates early and we can see bubbles in the bottom.