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All suspensions, including coarse emulsions, are inherently thermodynamically unstable. They will, through random motion of the particles over time, aggregate because of the natural and dominant tendency to decrease the large specific surface area and excess surface energy.
Why suspended particles become flocculated in a suspension?
Answer: Ionic surfactants cause flocculation by neutralizing the charge on each particle, resulting into a flocculated suspension. When the surfactants reduce the interfacial tension, the liquid becomes capable of displacing the adsorbed film of air from the surface of solid drug particle and facilitating wetting.
Is suspension stable or unstable?
Suspensions are unstable from a thermodynamic point of view but can be kinetically stable over a longer period of time, which in turn can determine a suspension’s shelf life. This time span needs to be measured in order to provide accurate information to the consumer and ensure the best product quality.
Which suspension is more stable and why?
Suspension is more stable. This is because suspension does not mix with each other. The denser particles settle down at the bottom and makes the solution stable.
What is suspending agent example?
: a substance (such as carrageenan, xanthan gum, or cellulose ether) that is added to fluids to promote particle suspension or dispersion and reduce sedimentation All these drinks can contain preservatives, and drinks other than juices can contain additives to colour, flavour and sweeten.
Is suspension can improve the chemical stability of a drug?
Suspension can improve chemical stability of certain drug. ➢Drug in suspension exhibits higher rate of bioavailability than other dosage forms.
Which is more stable among Fe3+ and Fe2+ Why?
The reason why fe3+ is more stable than fe2+ is because, in fe2+ there are 6 electrons in d orbital as compared to 5 electrons in the case of fe3+. Since 10 electrons make fully filled d orbital (most stable) , the 5 electrons in fe3+ makes the d orbital half filled and therefore is more stable compared to fe2+.
Why rheology is important for suspension stability?
Rheologic consideration is of great importance in the study of the stability of pharmaceutical suspensions. This is because the viscosity of a suspension can modify the sedimentation rate.
Why cu2+ is more stable than Cu+?
Stability depends on the hydration energy (enthalpy) of the ions when they bond to the water molecules. The Cu2+ ion has a greater charge density than Cu+ ion and thus forms much stronger bonds releasing more energy.
What is the stability problem of suspension?
Because suspensions are thermodynamically unstable system, physical stability of suspensions becomes as important as the chemical and biological stability. Physical stability of suspensions is the condition in which the particles do not aggregate and in which they remain uniformly distributed throughout the dispersion.
What are the qualities of ideal suspension?
Desirable properties of suspensions are that they should have good organoleptic properties, suspensions should possess good pourability leading to ease of removal of dose from container, the particle size distribution should be uniform, there should be ease of re dispersion of settled solid particles, they should be Dec 8, 2015
Is a suspension stable?
It is important to understand that suspensions are kinetically stable, but thermodynamically unstable, system. Physical stability is defined as the condition in which the particles remain uniformly distributed throughout the dispersion without any signs of sedimentation.
How do you overcome stability problems of suspension?
Increasing the viscosity – increasing the viscosity of the continuous phase can lead to the stability of suspensions. This is so because the rate of sedimentation can be reduced by increase in viscosity. Viscosity increase is brought about by addition of thickening agents to the external phase.
Why suspension is thermodynamically unstable?
All suspensions, including coarse emulsions, are inherently thermodynamically unstable. They will, through random motion of the particles over time, aggregate because of the natural and dominant tendency to decrease the large specific surface area and excess surface energy.
Why is Fe2+ oxidized Fe3+?
The pale green Fe2+ is oxidised to orange Fe3+ because it loses an electron. This is an oxidation reaction because there is a loss of electrons and an increase in oxidation number.
What is the stability of true solution?
Properties True solution Colloids Stability Solution is stable as the solute particles do not settle down when left undisturbed. Stable.
Is suspension stable class 9?
Suspensions are heterogeneous mixture of two or more substances. Particles of solute do not dissolve in solvent rather they remain suspended in bulk throughout. Therefore, suspension is not stable. The particles of suspension can be separated through the process of filtration.
Which is more stable Fe2+ or Fe3+?
Fe3+ is more stable than Fe2+. In Fe3+ ions, there are five 3d half-filled orbitals and is more symmetrical than Fe2+. Whereas in Fe2+ ion there are four 3d half-filled orbitals and one orbital is filled.
Why are suspensions not stable?
Suspensions are a heterogeneous mixture. When the suspension is left for some time, particles get settled in the bottom because they are heavy, larger, and have less movement thus settle down due to gravity. Therefore, suspension is not stable.
Why are suspending agents used?
They help in lowering the sedimentation rate of particles in suspension. They usually prevent caking at the base of an suspension . It could be resuspendend by agitation. It is majorly used as an excipients to help active pharmaceutical ingredients stay suspended in formulation.
How do I know if my suspension is stable?
Suspension stability can be theoretically estimated prior to the beginning of the formulating process based on the solid phase particle size, liquid phase density, and viscosity. Stokes equation can be used to predict suspension stability in order to save time and resources.
Which is more stable true solution or suspension?
Complete answer: True solutions are more stable than suspension. True solutions remain stable as the particles are almost uniform in size and do not settle down if left untouched for a given time interval.
Why suspension is unstable Class 9?
Suspension is a heterogeneous mixture. The particles of a suspension can be seen by the naked eye. The particles of a suspension scatter a beam of light passing through it and make its path visible. The solute particles settle down when a suspension is left undisturbed, that is, a suspension is unstable.
How do you stabilize suspension?
Stabilizing a suspension There are various routes that can be undertaken to improve suspension stability – for example, stabilization can be achieved by: preventing coagulation through inter-particle repulsion. slowing down sedimentation by increasing the viscosity of the continuous phase.
What are the types of suspending agents?
Suspending agents are grouped into three classes: synthetic, semi synthetic and the natural polysaccharides, in which class acacia, tragacanth and starch belong to the latter class (Mbang et al., 2004; Mahmud et al., 2010).
