Glass commonly used in laboratories and strong acid, alkali presentation

- Mar 03, 2018-

Glass commonly used in laboratories and strong acid, alkali presentation

I. Classification of glassware

Glass is made into various vessels and widely used in monitoring and analysis due to its chemical stability, thermal stability, mechanical strength and transparency.

The main component of glass is silica (SiO2). Based on different contents of calcium oxide (CaO), sodium oxide (Na2O), boron oxide (B2O3), borax (Na2B4O7·10H2O) and silicate, etc., glass is divided into ordinary glass (i.e., soda lime glass), hard glass (i.e., borosilicate glass) and quartz glass.

 The specific performances of various types of glass are shown in the following table


Glass category


Main ingredient and content


Category and performance of the instrument to be made, and name of the major instrument


Ordinary glass (soda lime glass)



SiO2: 70~75%


Na: 12~14%


Ca: 3~4%


Measuring vessels - not heatable. Commonly used measuring vessels include measuring cylinders, reagent bottles, volumetric flasks, burettes, colorimetric tubes, suckers, etc.


Hard glass (borosilicate glass)



SiO2: 80%




Na, K: 4~6%


Containers, flasks and beakers - heatable. Commonly used types include beakers, test tubes,  Erlenmeyer flasks, distilling flasks, etc.


Quartz glass



SiO2: 99.5%



Instruments for trace analysis and optical analysis, high temperature resistant and acid (except HF) resistant, capable of transmitting ultraviolet rays. Commonly used types include cuvettes, evaporating dishes, crucibles, etc.

II. Names and specifications of common glassware






Specifications (volume/mL)


Main purposes






50, 100, 250, 400, 500, 800, 1,000, 2,000


Sample dissolution and solution preparation




Erlenmeyer flask (conical flask)


100, 250, 500,1,000


Sampling for heat treatment and titration analysis




Volumetric flask


25, 50, 100, 200, 250, 500, 1,000 (colorless, brown)


Accurate preparation of standard solutions and sample dilution




Pipette (pipet)


1, 2, 5, 10, 15, 20, 25, 50, 100


Accurate transference of different amounts of liquid






Constant volume: 25, 50, 100


Titration analysis




Reagent bottle


60, 120, 250, 500, 1,000 (divided into colorless or brown)


Storage of liquid reagents (small mouth) and solid reagents (wide-mouth)




Dropping bottle


30, 60, 120


Containing various types of indicators and adding reagent dropwise in small amounts




Standard funnel


Diameter/mm: 50, 60, 75, 90, 120


Filtering and precipitating




Weighing bottle


Bottle diameter × height/mm: φ25 × 40, φ40 × 25, φ30 × 50, φ50 × 30, φ35 × 70, φ70 × 35


Flat shape for distributing and drying medicines, tall shape for gravimetric analysis (Open the lid before drying samples in the oven)




Colorimetric tube


10, 25, 50, 100


Colorimetric analysis






Diameter/mm: 120, 180, 210, 240


Placement of dried reagent and samples (not including overheated objects)


 III. Summary list of commonly used acids and alkalis for digestion of analyzed samples



Hydrochloric acid




Main properties of acidity, reducibility and coordinating properties for some metal ions.




Mainly used for the dissolution of weak acid salts (e.g. carbonate, phosphate, etc.), some basic oxides, some sulfides, metals beyond hydrogen in the potential order and alloys.




Hydrochloric acid is prone to volatilization loss.


Nitric acid




Strong oxidizing and acidic properties.




Almost all metals (except platinum, gold and some other precious metals, as well as iron, aluminum and chromium) and almost all sulfides and sulfide ores can be dissolved in nitric acid, which may also destroy organics which interfere with the determination.




Nitric acid is prone to decompose under acidic conditions and at high temperatures, and the nitric suboxide which often remains in the digested solution should be removed by boiling so as not to interfere with the subsequent analysis. Prone to combine with hydroxyl-containing compounds to form explosive esters, thus causing safety problems during the digestion process.


Sulfuric acid




Similar to nitric acid but with a lower oxidizing ability. It is characterized by a high boiling point (338℃) and the ability to digest samples at a high temperature and to destroy organics in the sample.




Alkaline earth metal sulfate and lead sulfate are insoluble in water.


Phosphoric acid




Pyrophosphate and polyphosphate formed under acidic conditions or at high temperatures coordinate with certain metals, which raises the boiling point of the digestion liquid.




Able to function alone or in combination with sulfuric acid. When in use, phosphoric acid can coordinate with other ions, which can eliminate interference caused by these ions.


Perchloric acid




Concentrated and hot perchloric acid has strong dehydration and oxidation actions.




Commonly used in the decomposition of stainless steel and sulfides and the destruction of organics. Able to oxidize chromium, vanadium, sulfur, etc. to corresponding high-valency oxides. Due to its high boiling point, low boiling point acid in perchloric acid can be removed by heating until it evaporates and smokes, and the remaining residue can easily decompose after adding water. For samples containing organics and reducing materials, first destroy them by adding nitric acid, then decompose them with perchloric acid or with a mixture of nitric acid and perchloric acid; the nitric acid should be added at any time during the oxidation process and its addition can only be stopped after all the samples have decomposed. In general, the presence of nitric acid during the use of perchloric acid can ensure safety.




When using perchloric acid, note that pure perchloric acid with a content less than 85% is stable under certain conditions, but violent explosions will occur when it is heated in combination with a strong dehydrating agent (e.g. concentrated sulfuric acid), organics or some reducing agents.


Hydrofluoric acid




Has a strong complexation on high valency elements and is strongly acidic.




Generally not used alone; often mixed with sulfuric acid, nitric acid or perchloric acid for use.




Corrosive to glass and pottery; platinum vessels are required for sample digestion.


NaOH solution




Strongly alkaline.




Used to decompose aluminum, aluminum alloys and certain acidic oxides. Decomposition should be carried out in vessels of silver or teflon.


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