Specific Gravity of Liquids and Solids: Methods and Principles in Physical Pharmacy

What is the procedure for determining the specific gravity of liquids by the flotation method?

1. Suspend the plummet from the hook. 2. Adjust leveling and foot screws until pointers coincide. 3. Fill the cylinder with the sample liquid. 4. Immerse the plummet in the liquid. 5. Place riders on the beam until pointers coincide, ensuring the plummet is fully immersed.

How is the first digit to the right of the decimal point determined in specific gravity readings?

The position of the 5g weight rider indicates the first digit (0.X).

What does the position of the 0.5g weight rider indicate in specific gravity readings?

It gives the value of the second digit to the right of the decimal point (0.0X).

What is the significance of the 0.05g weight rider in specific gravity readings?

It indicates the third digit to the right of the decimal point (0.00X).

What does the position of the 0.005g weight rider indicate in specific gravity readings?

It gives the value of the fourth digit to the right of the decimal point (0.000X).

What is the first step in determining the solubility of a solid sample in the pycnometer method?

Place a corn grain amount of the sample powder in 3 mL of water and observe if it is soluble or insoluble.

What should be done if the solid sample is insoluble in water during the pycnometer method?

Use water as the standard liquid and proceed to determine specific gravity.

What is the procedure for determining the specific gravity of a solid using the pycnometer method?

1. Weigh the empty pycnometer. 2. Fill it with standard liquid at 25°C and weigh. 3. Weigh the pycnometer with the solid powder added. 4. Fill with standard liquid again and weigh.

How is density defined in the context of specific gravity determination?

Density is defined as mass per unit volume at a fixed temperature and pressure, expressed in g/cm³ (CGS) or kg/m³ (SI).

What is specific gravity?

Specific gravity is the ratio of the mass of a substance to the mass of an equal volume of another substance taken as a standard, typically water for liquids and solids.

What are some methods for determining the specific gravity of liquids?

1. Pycnometer 2. Hydrometer 3. Mohr-Westphal balance.

What principle does the Mohr-Westphal balance operate on?

It measures buoyant force by placing weights on a notched beam to submerge the plummet to a constant reference point.

What is the role of the plummet in the flotation method for liquids?

The plummet, occupying 5mL, is immersed in the liquid and experiences a buoyant effect equal to the weight of the fluid displaced.

What are the categories for solids based on their solubility and density in water?

1. Solid insoluble and heavier than water 2. Solid soluble and heavier than water 3. Solid insoluble and lighter than water 4. Solid soluble and lighter than water.

What is the difference between density and specific gravity?

Density is a concrete number that varies with measurement systems, while specific gravity is a dimensionless ratio that remains constant for each substance.

What is the significance of the standard liquid in specific gravity determination?

The standard liquid, typically water, is used to compare the mass of the substance being measured.

What is the purpose of the graduated cylinder in specific gravity determination?

It is used for the immersion of solids in a transparent liquid to measure specific gravity.

What is the Mohr-Westphal balance primarily used for?

It is used for determining the specific gravity of liquids by measuring the buoyant force on a submerged plummet.

What is the function of the riders on the Mohr-Westphal balance?

Riders are used to measure the buoyant force by adjusting the weight on the notched beam.

What is the importance of using equal amounts of powder and liquids in solubility testing?

Equal amounts ensure proper comparison of solubility across different liquids.

What is the temperature at which the pycnometer should be filled with the standard liquid?

25°C.

What is the significance of the loss of weight or displacement in the pycnometer method?

It is used to determine the specific gravity of solids by measuring the weight of the liquid displaced.

What types of hydrometers are mentioned for specific gravity determination?

1. Baume Hydrometer 2. Alcoholometer 3. Twadell's Hydrometer 4. Cartier's Hydrometer.

What is the function of Lovis beads in specific gravity determination?

Lovis beads are balloon-shaped glass objects with specific gravity values marked on them, used for measuring specific gravity.

What is the method of immersion of solid in transparent liquid used for?

It is used to determine the specific gravity of solids.