2. Chemicals and Apparatus

• The right reagent must be selected because the higher the purity, the higher the accuracy.
• Interferences are eliminated the more pure a reagent is.
• RCC of ACS (Reagent Chemical Committee of American Chemical Society) is responsible for grading or assessing reagents.
• There are two kinds of reagents: Reagent Grade and Special Reagent Grade.
• Reagent Grade is conformed to the standard of the RCC and is often applied for analytical works.
• Primary Standard is 99.9% Purity.
• Secondary Standard is more reactive than the primary standard and its concentration cannot be determined.
• Special Reagent Grade is used for specific applications such as spectrophotometry and liquid chromatography.
• All vessels containing a sample must be identifiable.
• Glassware must be cleaned thoroughly before use.
• Chemicals may be used in removing grease films.
• Evaporating Liquids are usually done to remove impurities.
• Bumping refers to volatile, sudden, and boiling splatters.
• Wet Ashing involves oxidizing agents like nitric acid and sulfuric acids being applied to organic solvents.
• Analytical Balance carries 1g - kgs and has a precision of 1 x 10^5.
• Macro Balance carries 160 - 220 g and has a precision of 0.1 mg.
• Semi Micro Balance carries 10 - 30 g and has a precision of 0.01 mg.
• Micro Balance carries 1 - 10 g and has a precision of 0.001 mg.
• Auxiliary Balance is less precise and accurate, used when measurement does not need precision.
• Top Loading Auxiliary Balance carries 150 - 200g with 1 mg precision.
• Triple Beam Balance is simple, durable, inexpensive weighing.
• Decantation - pouring liquid gently to not disturb the precipitate
• Gives precise volume of water and is used to prepare standard solutions
• Meniscus: The curvature of water due to atmospheric interferences
• Measurement of Volume
• Ashing Filter Paper - Burning the ashing paper until the precipitate is left
• Sintered Glass/Fritted Glass - high temperatures up to 200 degrees without damage
• Backwashing - turning crucible upside down and washing
• Microwave Oven: Speeds up Heating
• Weighing by Difference: Determining series of sample weights
• Constant value of alpha: 0.025
• Filtering and Washing Precipitate
• Measured fraction of the volume of a liquid solution
• Volumetric/Transfer: Fixed volume between 0.5 to 20 mL
• Hygroscopic Solid: Rapidly absorbs moisture from atmosphere
• Parallax: Change in measurement reading depending on the position of the observer
• Simple Crucible
• Burner: Intense heat
• The observer should face the meniscus at eye level or perpendicularly for accurate reading
• Filtration Paper