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Questions and Answers

What is Micromeritics?

Micromeritics is the science and technology of small particles.

In a polydisperse sample, which two properties are important?

The shape and surface area of the individual particles.
The color and texture of the individual particles.
The size range and number or weight of particles present.
Both B and C. (correct)

How is the size of a sphere expressed?

The size of a sphere is readily expressed in terms of its diameter.

Define equivalent spherical diameter.

Equivalent spherical diameter relates the size of a particle to the diameter of a sphere having the same surface area, volume, or diameter. Signup and view all the answers

Which diameter describes the diameter of a sphere having the same surface area as that of the asymmetric particle?

Surface diameter (ds) (C) Signup and view all the answers

What is dsieve?

Diameter of a sphere that passes through the same sieve aperture as the asymmetric particle. (D) Signup and view all the answers

What does the Polydispersity Index (PDI) measure?

The Polydispersity Index (PDI) is used as a measure of broadness of molecular weight distribution. Signup and view all the answers

What size range of particles can be measured by optical microscopy?

0.2-100 μm (A) Signup and view all the answers

What is the main advantage of optical microscopy?

Microscopy allows the observer to view the particles directly. Signup and view all the answers

Which of the following is a disadvantage of optical microscopy?

Diameter is obtained from only two dimensions. (B) Signup and view all the answers

What size range of particles can be estimated by the sieving method?

Particles having a size range between 50 & 1500µm are estimated by sieving method. Signup and view all the answers

The sieving method gives number distribution

False (B) Signup and view all the answers

What percentage of fine powder (passed through mesh 100) should normally be present in granulated material?

Normally 15% of fine powder (passed through mesh 100) should be present in granulated material. Signup and view all the answers

In the sieving method, how are sieves arranged?

With the coarsest at the top. (B) Signup and view all the answers

What is the Sedimentation method used for?

Sedimentation method is used for formulation & evaluation of suspension formulation & evaluation of emulsions and determination of molecular weight of polymers. Signup and view all the answers

What range applies to particles measured using the Sedimentation method?

Sedimentation method may be used over a size range of 1 to 200μm. Signup and view all the answers

What is measured in the Conductivity method?

In fact, particle volume is measured & converted in to particle diameter. Signup and view all the answers

Match the parameters measured with the equipment used:

Coulter counter = Particle Volume Sieves = Particle Size Optical micrometer = Particle Diameter Signup and view all the answers

What is measured in Powder surface area determination Methods?

Specific surface: surface area of a powder can be calculated using particle size data which are obtained by one of the methods mention already. Signup and view all the answers

List two Powder surface area determination Methods.

The commonly used methods are: a. Adsorption b. Air Permeability Signup and view all the answers

What is measured in the Adsorption Method?

Amount of gas that is adsorbed to form a monomolecular layer on the adsorbent istaken into account. Signup and view all the answers

What is measured in the Air Permeability Method?

The permeability of air for a given pressure drop is inversely proportional to specific surface. Signup and view all the answers

What does a high value in the angle of repose imply?

The value of the angle of repose will be high if the powder is cohesive and low if the powder is non-cohesive. Signup and view all the answers

Give the formula to measure the Angle of repose

tan Ø = h/r where h is the height of the powder cone and r is the radius of the powder cone. Signup and view all the answers

Define true volume.

The true volume, V, of a powder is the space occupied by the powder exclusive of spaces greater than the intramolecular space. Signup and view all the answers

Define porosity.

It is the void volume exclusive of powder material. Signup and view all the answers

Define bulk density.

It is the weight of bulk divided by its bulk volume. Signup and view all the answers

Flashcards

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