The Viscometer Of An Ideal

Rheology is the study of fluid flow and deformation of solids. Resistance is offered as part of a fluid (liquid or gas) moves to the other. The force required to drag a layer of fluid past another with a given speed is called shear stress, while the number of the movement called the number of shear. Resistance to this movement is called viscosity. The viscosity of a fluid can be defined as the force per unit area required to maintain a unit velocity between two parallel planes of fluid separated by a distance unit. This is mathematically written as the viscosity is equal to the force per unit area (F? A) (Dynesen / sq cm) / velocity gradient perpendicular to the plane per second (dv / dx). The units of viscosity is balance. Like most pharmaceutical liquids have a relatively low viscosity units are often centipoise (cps) or 0.01 poise. The new units are internationally millipascal or MPC.

They have the same numerical value as a CPS, so that the CPP is equal to a CPS.

Pure liquids and solutions are real constant viscosity at a given temperature and pressure. Such fluids are called Newtonian fluids. Viscosity of these fluids are reduced at high temperatures. This suggests the existence of molecular clusters. association, or liquids. Increasing the temperature or the kinetic energy interferes with these associations, because of the reduction in viscosity. The solutions of liquid or very partner dipole interaction can vary greatly from viscosity. These solutions may occur in up to their viscosity is greater than the individual components. The ideal solution would not be a viscosity shows, which is a direct sum of the percentage of each component mole fraction basis. This is an inverse relationship can be expressed mathematically, and 1 / = viscosity of the solution (components 1/viscosity a) times the mole fraction of components in a single + (1/viscosity part two) times the mole fraction of the two components.

In multiphase liquid medicines (dispersions of rubber or other polymers) the degree of shear is not directly proportional to the shear stress and viscosity is not constant. These fluids are called non-Newtonian fluids. Because of the difficulty in measuring these mixtures, we will evaluate only Newtonian fluids in this laboratory. However, the nature of non-Newtonian mixtures will be discussed in the conference.

Clinically, we know that changes in blood viscosity may indicate the disease state. ESR is an index of plasma viscosity.

PROCEDURE:

The absolute viscosity can be measured directly by measuring the time required for a measured volume of the liquid stream through a capillary under an applied pressure. The experimental determination of the absolute viscosity is a difficult task. The measure of the relative viscosity is an easy task. Therefore, the relative viscosity is measured using reference fluids of known viscosity. We will use an Ostwald viscometer. You will be able to see a video about the proper use of the viscometer. You also need to be able to use a Westphal balance to measure the density of the solution are being prepared. Also shown in the video.

Ostwald viscometer with the driving pressure of the liquid in the capillary depends on the difference in liquid level (h) the liquid density (rho) and the acceleration of gravity (g). This is called hydrostatic pressure. This pressure represents the shear stress. The flow rate of fluid in the capillary is the cutting speed. Therefore, the viscosity of a liquid is proportional to the hydrostatic pressure divided by the volume of fluid flowing through the capillaries per unit of time. Using the same visometer to take action that the conditions of H & G and the volume is constant and can establish that the relation between the viscosity of a liquid with the viscosity of the second is the relationship between the time it takes to get through the viscometer times the density of liquid, both for liquids.