Respuesta :
Answer:
γ = 0.06563 N / m
9.78% difference
Explanation:
Solution:-
- Surface tension is the ability of any fluid to resist any external force which causes a decreases in surface area of the impact area due to inward compressive forces. These compressive forces occur due to cohesive nature of the fluid molecules.
- Mathematically, surface tension ( γ ) is defined as the force felt per unit length by the fluid.
              γ = F / L
Where,
       F: Force imparted
       L: The length over which force is felt
- We are given the mass ( M ) of ( n = 100 ) water droplets to e 3.78 g. The mass of a single droplet ( m ) can be evaluated as follows:
             m = M / n
             m = 3.78 / 100
            m = 0.0378 g    Â
- The force ( F ) imparted by a single drop of water from the burette can be determined from the force balance on a single droplet. Assuming the distance over which the drop falls is negligible and resistive forces are negligible. Then the only force acting on the droplet is due to gravity:
            F = m*g
            F = 0.0378*9.81*10^-3
            F = 0.000370818 N   Â
- The length over which the force is felt can be magnified into a circular area with diameter equal to that of a single droplet ( d ). The circumferential length ( L ) of the droplet would be as follows:
            L = π*d
            L = π*( 0.0018 )
            L = 0.00565 m
- Then the surface tension would be:
            γ = F / L
            γ = 0.000370818 / 0.00565
            γ = 0.06563 N / m
- The tabulated value of water's surface tension is given as follows:
            γa = 0.07275 N/m
- We will determine the percentage difference between the value evaluated  and tabulated value as follows:
           [tex]p.diff = \frac{gamma_a - gamma}{gamma_a} * 100\\\\p.diff = \frac{0.07275- 0.06563}{0.07275} * 100 \\\\p.diff = 9.78 %[/tex]
- The %difference between is within the allowable practical limits of 10%. Hence, the evaluated value ( γ = 0.06563 N / m ) can be accepted with 9.78% error.
