طرق قياس تركيز المحاليل

Methods for Measuring Solution Concentration

• Measuring the concentration of saline and sugar solutions is important for obtaining a homogeneous product with consistent sugar or salt concentrations, ensuring high product quality.

Measurement Methods

• Direct methods involve direct measurement using instruments like refractometers and hydrometers.
• Indirect methods involve techniques like using a density bottle (pycnometer) and a Westphal balance.

Density Bottle (Pycnometer)

• Density bottles are one of the most accurate methods for determining the specific gravity (relative density) of a liquid.
• A density bottle is a glass container with a stopper having a capillary hole to allow excess liquid to escape when the stopper is inserted.
• Common volumes for density bottles are 5, 10, or 50 ml.

Procedure

• Weigh the empty, dry density bottle (a).
• Fill the bottle with distilled water and weigh again (b).
• Empty and dry the density bottle.
• Fill the bottle with the solution to be tested for its specific gravity and weigh (c).

Specific Gravity Calculation

• Specific gravity is the ratio of the weight of a certain volume of a substance at a given temperature to the weight of an equal volume of water at the same temperature.
• Specific Gravity = (Weight of Solution) / (Weight of Water) = (c - a) / (b - a)
• Density = Specific Gravity of Substance × Density of Water
• Density = Specific Gravity × 1
• Specific Gravity = Density / Density of Water

Westphal Balance

• The Westphal balance is based on Archimedes' principle, which states that when an object is immersed in a fluid, it experiences an upward buoyant force equal to the weight of the fluid displaced by the object.
• It consists of a glass float (plunger) with a volume of 5 cm³.
• The balance comes with five riders (weights).

Westphal Balance Riders

• There are five riders where increasing the rider number decreases its weight (inverse relationship):
• The first and second riders weigh 5 grams.
• The third rider weighs 0.5 grams.
• The fourth rider weighs 0.05 grams.
• The fifth rider weighs 0.005 grams.

Calculation Method for Westphal Balance

• If the first rider is used on the 10th division, it gives a value of 1 (whole number).
• If the second rider is used, it gives the first decimal place of the reading.
• If the third rider is used, it gives the second decimal place and so on.
• If the fourth rider is used, it gives the third decimal place and so on.
• If the fifth rider is used, it gives the fourth decimal place.
• If a rider is not used, its position is represented by zero.

Example Calculation

• Example showing how to use a Westphal balance for density determination demonstrating how values from different riders contribute to the overall reading
• First rider at the 1st division = 1
• Second rider at the 1st division gives a value of 1.
• Fifth rider at the fifth division gives a value of 5
• Fourth rider unused (0).
• Fifth rider at ninth division gives a value of 9.
• This indicates that the density of the solution is 1.1509 and so on

Measuring Mash Concentration

• The concentration of mash (or must) can be determined through a specific chart.