Surface tension, Viscosity

SURFACE TENSION

Surface tension is defined as the force acting per unit length perpendicular to the line drawn on the surface of liquid. It is denoted by Greek letter γ (Gamma). It has dimensions of kg s^-2 and in SI unit it is expressed as N m^-1. Surface tension reduces with increase in temperature.

​SURFACE TENSION VS. TEMPERATURE PLOT

​VISCOSITY

It is one of the characteristic properties of liquids. Viscosity is a measure of resistance to flow which arises due to the internal friction between layers of fluid as they slip past one another while liquid flows.

​F   A                   (A is the area of contact)

F                   (where, is velocity gradient)

 

‘n’ is proportionality constant and is called coefficient of viscosity.

Viscosity coefficient is the force when velocity gradient is unity and the area of contact is unit area.

SI unit of viscosity coefficient is Newton second per square meter (N s m^-2) = Pascal second (Pa s = 1kg m^-1s^-1). In cgs system the unit of coefficient of viscosity is poise

1 poise = 1 g cm^-1s^-1 = 10^-1kg m^-1s^-1

IMPORTANT FORMULA

1.  Ideal gas  PV = nRT =   
2. Graham’s law of diffusion  
3. Separation by diffusion f=n1'n2'n1n2=AfterBefore    f1=M2M1=one stage separation f1=f here x=no. of shape   Kinetic Theory  PV = 1/3 mnv²_rms
4. Kinetic Energy/mole = 3/2 RT
5. Kinetic Energy/molecule = 3/2 kT     k(Boltzmann constant) =R/N_A
6. 
7. 
8.  
9. v_rms: v_avg: v_MP = 1.224 :1.128:1 = 1: 0.92 :0.816
10. Vanderwaal’s Gas  
11. Boyles temp T_b =  
12. Critical constants   
13. Inversion temperature
14. C_p – C_V = R and C_P/C_V = g
15. Compression factor Z =    Z = 1 for ideal gas (Z < 1 lower P      Z > 1 higher P)
16. C_p – C_v = R    and   C_p/C_v = g

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