Question

Calculate the gauge pressures inside the following spherical bubbles. Use the surface tension values given in the table below. A 1.55-cm-radius bubble of water. A 1.85-cm-radius bubble of toluene. A 2.65-cm-radius bubble of ethanol.

Answer 1

Given

Water bubble of radius R1 = 1.55 cm , surface tension is gamma1 = 0.0728 N/m

bubble of toluene R2 = 1.85 cm ,surface tension is gamma2 = 0.0277 N/m

bubble of ethanol R3 = 2.65 cm ,surface tension is gamma3 = 0.0223 N/m

we knwo that the gauge pressure is dP = 4*gamma/R

for water bubble the gauge pressure is dP = 4*0.0728/(1.55*10^-2) N/m2 = 18.787 N/m2

for bubble of toluene the gauge pressure is dP = 4*0.0277/(1.85*10^-2) N/m2 = 5.989 N/m2

for bubble of ethanol the gauge pressure is dP = 4*0.0223/(2.65*10^-2) N/m2 =3.366 N/m2