Questions and Answers
What is specific gravity defined as?
What is the primary purpose of a pycnometer?
In which step during the specific gravity measurement process is distilled water used?
How does specific gravity affect whether a substance will float or sink in water?
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What does specific gravity typically compare?
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Which property is directly involved in determining specific gravity?
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What characteristic of the glass stopper on a pycnometer is important?
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Why is knowing the specific gravity of pharmaceutical materials important?
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What is the standard temperature for specific gravity determination as defined by the USP?
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How is specific gravity expressed in units?
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What volume range is typically available for a pycnometer?
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What does apparent specific gravity refer to?
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What does relative density specifically compare?
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What role does the analytical balance play in measuring specific gravity?
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Which of the following best describes density?
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What is the first step in determining the specific gravity of a liquid?
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What does a specific gravity value indicate about a liquid?
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Which principle does the Mohr Westphal balance utilize?
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What does temperature affect in specific gravity determination?
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Which of the following liquids has a standard specific gravity greater than 1.25?
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What is meant by the term 'unitless' in the context of specific gravity?
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Which system is commonly used as the standard for specific gravity determination?
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What could affect the accuracy of the Mohr Westphal balance readings?
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What will occur if the experimental specific gravity is less than the standard specific gravity?
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What do the terms 'boiling point' and 'congealing point' contribute to in specific gravity determination?
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What is the role of the thin platinum wire in the Mohr Westphal balance?
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Why is the Mohr Westphal balance incapable of providing highly accurate readings?
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Which of the following liquids is likely to float when measured in the Mohr Westphal balance?
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What is the significance of specific gravity in the context of chemical liquids?
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How does the Mohr Westphal balance operate?
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Specific gravity is defined as the ratio of mass of a substance to the mass of an equal volume of another substance taken as STD.
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The common practice for determining specific gravity is based on a metric temperature of 30 deg./30 deg.
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Specific gravity can be expressed in units such as pounds per cubic foot (lb/ft³).
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Density is a term that refers only to the mass of a substance without considering its volume.
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Water has a specific gravity value numerically equal to 2 for standard determinations.
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The determination of specific gravity requires measuring temperature, which can affect the results.
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The apparent density is the same as specific gravity and can be used interchangeably.
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Specific gravity determination is always affected by air pressure conditions.
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The specific gravity of a substance indicates its identity and purity within certain contexts.
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The definition of specific gravity varies between the metric and English systems.
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Specific gravity is the ratio of the mass of a substance to the mass of an equal volume of standard fluid.
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The pycnometer is a device used exclusively for measuring atmospheric pressure.
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To determine specific gravity, it is essential to weigh the pycnometer when it is filled with both distilled water and the sample liquid.
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A specific gravity value greater than 1 indicates that the liquid will float in water.
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The stopper of a pycnometer features a capillary tube that allows for air bubbles to escape.
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Specific gravity is dimensionless, meaning it has no units.
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A pycnometer can have a volume range from 5 mL to 50 mL.
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Measuring the specific gravity of pharmaceutical materials can help evaluate their flow properties.
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The first step in using a pycnometer is to fill it with the sample liquid.
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The pycnometer aids in determining the relative density of both solids and liquids.
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The specific gravity of clove oil ranges from 1.038 to 1.060.
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Ethyl alcohol has a standard specific gravity of exactly 0.816.
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Glycerin has a standard specific gravity of less than 1.249.
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A Mohr Westphal balance utilizes the principle of buoyancy for measuring specific gravity.
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The ability of the Mohr Westphal balance to provide accurate readings is unaffected by temperature changes.
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If a substance's experimental specific gravity is higher than the standard specific gravity, it will sink in water.
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A lighter liquid in the Mohr Westphal balance will float while a heavier liquid will sink.
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Syrup has a specific gravity of 1.313.
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The alignment of the pointers on the Mohr Westphal balance is solely automated.
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The weight of the empty pycnometer is not necessary for calculating specific gravity.
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Study Notes
Specific Gravity Determination of Liquids
- Specific gravity (sp.gr) is the ratio of the mass of a substance to the mass of an equal volume of another substance, typically water.
- Density is defined as mass of the substance per unit volume, measured in g/mL.
- Specific gravity is unitless and is commonly expressed as a numerical value, typically based on water's density.
- The standard measurement for sp.gr is typically taken at 25°C (25°/25°), allowing for consistent comparison.
Methodology
- A pycnometer is a special glass bottle used for determining specific gravity through precise weight measurements of defined volumes.
- The pycnometer features a fitted glass stopper with a capillary tube to release air bubbles during measurement.
- Steps in determining sp.gr using a pycnometer:
- Weigh the clean, dry empty pycnometer.
- Weigh the pycnometer filled with distilled water.
- Weigh the pycnometer filled with the sample liquid.
- Calculate the specific gravity using the formula that compares the weight of the sample liquid to the weight of the water.
Equipment and Principles
- Mohr Westphal Balance operates on Archimedes' Principle of buoyancy to measure densities.
- The balance involves suspending a glass tube in the sample liquid via a thin platinum wire, observing whether the plummet sinks or floats to infer the liquid's density.
- While it can give quick approximations of specific gravity, the device's accuracy can be compromised by temperature variations and human error.
Importance of Specific Gravity
- Specific gravity is crucial in determining the identity and purity of liquid substances, aiding in characterizing chemical liquids.
- Monitoring relative density of solid pharmaceutical materials is significant during the design and scale-up of manufacturing processes for drug products.
- If experimental sp.gr is less than standard sp.gr, it indicates potential differences in density compared to known values.
Standard Specific Gravities of Common Liquids
- Clove Oil: 1.038 – 1.060
- Ethyl Alcohol: Not More Than (NMT) 0.816
- Liquid Petrolatum: 0.860 – 0.905
- Glycerin: Not Less Than (NLT) 1.249
- Syrup: 1.313
Specific Gravity Determination of Liquids
- Specific gravity (sp.gr) is the ratio of the mass of a substance to the mass of an equal volume of another substance, typically water.
- Density is defined as mass of the substance per unit volume, measured in g/mL.
- Specific gravity is unitless and is commonly expressed as a numerical value, typically based on water's density.
- The standard measurement for sp.gr is typically taken at 25°C (25°/25°), allowing for consistent comparison.
Methodology
- A pycnometer is a special glass bottle used for determining specific gravity through precise weight measurements of defined volumes.
- The pycnometer features a fitted glass stopper with a capillary tube to release air bubbles during measurement.
- Steps in determining sp.gr using a pycnometer:
- Weigh the clean, dry empty pycnometer.
- Weigh the pycnometer filled with distilled water.
- Weigh the pycnometer filled with the sample liquid.
- Calculate the specific gravity using the formula that compares the weight of the sample liquid to the weight of the water.
Equipment and Principles
- Mohr Westphal Balance operates on Archimedes' Principle of buoyancy to measure densities.
- The balance involves suspending a glass tube in the sample liquid via a thin platinum wire, observing whether the plummet sinks or floats to infer the liquid's density.
- While it can give quick approximations of specific gravity, the device's accuracy can be compromised by temperature variations and human error.
Importance of Specific Gravity
- Specific gravity is crucial in determining the identity and purity of liquid substances, aiding in characterizing chemical liquids.
- Monitoring relative density of solid pharmaceutical materials is significant during the design and scale-up of manufacturing processes for drug products.
- If experimental sp.gr is less than standard sp.gr, it indicates potential differences in density compared to known values.
Standard Specific Gravities of Common Liquids
- Clove Oil: 1.038 – 1.060
- Ethyl Alcohol: Not More Than (NMT) 0.816
- Liquid Petrolatum: 0.860 – 0.905
- Glycerin: Not Less Than (NLT) 1.249
- Syrup: 1.313
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Description
This quiz focuses on the determination of specific gravity for liquids as part of the Physical Pharmacy Lab curriculum. Students will review key concepts and methodologies relevant to measuring and understanding specific gravity in various liquid samples.
